| antimutagenic effects of milk fermented by lactobacillus helveticus l89 and a protease-deficient derivative. | the antimutagenic effects of whey, acetone extracts, and protein fractions isolated from milk that had been fermented by lactobacillus helveticus l89 were investigated using the mutagen 4-nitroquinoline-n'-oxide in the ames test (salmonella typhimurium ta 100). fermented milk significantly inhibited mutagenesis induced by 4-nitroquinoline-n'-oxide. however, milk fermented by a nonproteolytic variant of the same strain showed no inhibitory effects. results were similar for the whey fractions and ... | 1997 | 9313136 |
| controlled gene expression systems for lactic acid bacteria: transferable nisin-inducible expression cassettes for lactococcus, leuconostoc, and lactobacillus spp. | a transferable dual-plasmid inducible gene expression system for use in lactic acid bacteria that is based on the autoregulatory properties of the antimicrobial peptide nisin produced by lactococcus lactis was developed. introduction of the two plasmids allowed nisin-inducible gene expression in lactococcus lactis mg1363, leuconostoc lactis nz6091, and lactobacillus helveticus cnrz32. typically, the beta-glucuronidase activity (used as a reporter in this study) remained below the detection limit ... | 1997 | 9361443 |
| a modified form of a vitamin b12 compound extracted from whey fermented by lactobacillus helveticus. | the content of vitamin b12 in whey was reduced considerably during lactic acid fermentation, which was analogous to the lactic acid fermentation of milk. this apparent b12 decrease in whey was caused by b12 compounds that were unextractable by conventional extraction with potassium cyanide but that could be extracted by sonication and treatment by proteases such as pepsin and papain. forms of the extracted b12 compounds were examined by bioautographies with escherichia coli 215, coupled with cel ... | 1997 | 9406064 |
| lactobacilli carry cryptic genes encoding peptidase-related proteins: characterization of a prolidase gene (pepq) and a related cryptic gene (orfz) from lactobacillus delbrueckii subsp. bulgaricus. | two genes, pepq and orfz, encoding a prolidase and a prolidase-like protein, respectively, were cloned and characterized from lactobacillus delbrueckii subsp. bulgaricus. the identity of the pepq and orfz genes with the lactobacillus delbrueckii subsp. lactis prolidase gene (pepq) was shown to be 98% and 60%, respectively. both pepq and orfz were preceded by a putative promoter region. northern analysis of pepq mrna revealed a 1.1 kb transcript indicating that pepq forms a monocistronic transcri ... | 1997 | 9421914 |
| a novel bacillus natto plasmid pls32 capable of replication in bacillus subtilis. | plasmid pls32 is a relatively large (approximately 70 kbp), cryptic, low copy-number plasmid present in bacillus natto. we isolated and analyzed the replication region of the plasmid in b. subtilis, and the following results were obtained: the replication region contained an open reading frame encoding a 287-amino acid protein (repn), whose amino acid sequence was partially homologous with those of the rep proteins encoded on plasmids pad1 and plj1 isolated from enterococcus faecalis and lactoba ... | 1998 | 9490016 |
| the s-layer gene of lactobacillus helveticus cnrz 892: cloning, sequence and heterologous expression. | lactobacillus helveticus cnrz 892 contains a surface layer (s-layer) composed of protein monomers of 43 kda organized in regular arrays. the gene encoding this protein (slph) has been cloned in escherichia coli and sequenced. slph consists of 440 codons and is preceded by a ribosome-binding site (rbs) and followed by a putative rho-independent terminator. indeed, northern analysis revealed that slph is a monocistronic gene. the gene is preceded by a possible promotor of which the -35 and -10 hex ... | 1998 | 9534241 |
| cloning and characterization of a prolinase gene (pepr) from lactobacillus rhamnosus. | a peptidase gene expressing l-proline-beta-naphthylamide-hydrolyzing activity was cloned from a gene library of lactobacillus rhamnosus 1/6 isolated from cheese. peptidase-expressing activity was localized in a 1.5-kb saci fragment. a sequence analysis of the saci fragment revealed the presence of one complete open reading frame (orf1) that was 903 nucleotides long. the orf1-encoded 34.2-kda protein exhibited 68% identity with the pepr protein from lactobacillus helveticus. additional sequencing ... | 1998 | 9572959 |
| characterization of is1515, a functional insertion sequence in streptococcus pneumoniae. | we describe the characterization of a new insertion sequence, is1515, identified in the genome of streptococcus pneumoniae i41r, an unencapsulated mutant isolated many years ago (r. austrian, h. p. bernheimer, e. e. b. smith, and g. t. mills, j. exp. med. 110:585-602, 1959). a copy of this element located in the cap1ei41r gene was sequenced. the 871-bp-long is1515 element possesses 12-bp perfect inverted repeats and generates a 3-bp target duplication upon insertion. the is encodes a protein of ... | 1998 | 9580131 |
| role of streptococcus thermophilus mr-1c capsular exopolysaccharide in cheese moisture retention. | recent work by our group has shown that an exopolysaccharide (eps)-producing starter pair, streptococcus thermophilus mr-1c and lactobacillus delbrueckii subsp. bulgaricus mr-1r, can significantly increase moisture retention in low-fat mozzarella (d. b. perry, d. j. mcmahon, and c. j. oberg, j. dairy sci. 80:799-805, 1997). the objectives of this study were to determine whether mr-1c, mr-1r, or both of these strains are required for enhanced moisture retention and to establish the role of eps in ... | 1998 | 9603827 |
| classification of lactobacillus helveticus strains by immunological differences in extracellular proteinases. | polyclonal antibodies against an extracellular proteinase of lactobacillus helveticus cp53 were raised. the antibodies reacted with a 170-kda enzyme with activity and a 53-kda protein that seemed to be a degradation product of the 170-kda proteinase from results of immunoblotting. the antibodies reacted also with a 45-kda extracellular proteinase of l. helveticus cp790. however, monoclonal antibodies to the cp790 proteinase did not react with the proteinase of l. helveticus cp53. seventeen strai ... | 1998 | 9692208 |
| preliminary characterization of microflora of comté cheese. | the evolution of the microflora of three comté cheeses made in duplicate with raw milk from three different sources was followed during ripening. the same starter was used with each type of milk. the comparison of the cheeses did not reveal any significant difference in the development of the microflora. starter lactic acid bacteria (streptococcus thermophilus and lactobacillus helveticus), which are added at the beginning of manufacture, decreased quickly in the first stages of ripening support ... | 1998 | 9721662 |
| genetic characterization and physiological role of endopeptidase o from lactobacillus helveticus cnrz32. | a previously identified insert expressing an endopeptidase from a lactobacillus helveticus cnrz32 genomic library was characterized. nucleotide sequence analysis revealed an open reading frame of 1,941 bp encoding a putative protein of 71.2 kda which contained a zinc-protease motif. protein homology searches revealed that this enzyme has 40% similarity with endopeptidase o (pepo) from lactococcus lactis p8-2-47. northern hybridization revealed that pepo is monocistronic and is expressed througho ... | 1998 | 9726890 |
| genotypic heterogeneity among lactobacillus helveticus strains isolated from natural cheese starters. | a total of 23 strains of lactobacillus helveticus isolated from natural whey starter cultures for italian hard cheeses and three reference strains were characterized by plasmid profiling, ribotyping and random amplified polymorphic dna (rapd) fingerprinting. the data showed an interesting strain heterogeneity in natural cheese starters, that seemed not only strain-dependent, but also related to the source of isolates. nineteen of the strains tested harboured extrachromosomal elements, whilst 11 ... | 1998 | 9750270 |
| electrophoretic pattern of peptidoglycan hydrolases, a new tool for bacterial species identification: application to 10 lactobacillus species. | lactobacilli have been used as industrial starters for a long time, but in many cases their phenotypic identification is still neither easy nor reliable. previously we observed that the cell wall peptidoglycan hydrolases of lactobacillus helveticus were highly conserved enzymes; the aim of the present work was to determine whether peptidoglycan hydrolase patterns obtained by renaturing sds-page could be of interest in the identification of lactobacilli species. for that purpose, the peptidoglyca ... | 1997 | 9765824 |
| characterization of the lactobacillus helveticus groesl operon. | this study utilized inverse polymerase chain reactions to characterize a 2.7-kb region of the lactobacillus helveticus lh212 chromosome that included two complete and one truncated open reading frames (orfs). protein homology searches showed that the first two orfs encoded homologs to the universally conserved heat shock proteins groes and groel. amino acids encoded by the 5' end of the truncated orf that was downstream of groel showed good homology to the amino terminal end of the streptococcus ... | 1998 | 9766226 |
| conservation of the major cold shock protein in lactic acid bacteria. | primers designed from consensus regions of the major cold shock gene of different bacterial species were used in pcr amplification of lactic acid bacteria (lab). an appropriately-sized pcr product was obtained from lactococcus lactis subsp. lactis ll43-1 and mg1363; lactococcus lactis subsp. cremoris lc10-1, lc11-1, and lc12-1; streptococcus thermophilus st1-1; enterococcus faecalis ef1-1; lactobacillus acidophilus la1-1; lactobacillus helveticus lh1-1; pediococcus pentosaceus pp1-1; and bifidob ... | 1998 | 9767713 |
| molecular characterization of a stress-inducible gene from lactobacillus helveticus. | a gene (htra) coding for a stress-inducible htra-like protein from lactobacillus helveticus cnrz32 was cloned, sequenced, and characterized. the deduced amino acid sequence of the gene exhibited 30% identity with the htra protein from escherichia coli; the putative catalytic triad and a pdz domain that characterize the htra family of known bacterial serine proteases were also found in the sequence. expression of the l. helveticus htra gene in a variety of stress conditions was analyzed at the tr ... | 1998 | 9829922 |
| effectiveness of chemometric techniques in discrimination of lactobacillus helveticus biotypes from natural dairy starter cultures on the basis of phenotypic characteristics | lactobacillus helveticus is the dominant organism in natural starter cultures used for the production of typical italian cheeses. in this study, 74 l. helveticus strains, isolated from grana and provolone cheese natural whey starters, were distinguished with respect to their origin by using both cell wall protein profiles and chemometric evaluation of some phenotypic parameters, such as the ability to acidify cultures and the presence of nonspecific proteolytic and peptidase activities. cell wal ... | 1999 | 10103235 |
| rapid detection of listeria monocytogenes by a pcr assay specific for an aminopeptidase. | specific and rapid detection of listeria monocytogenes is very important with regard to food safety since all other species of listeria appear to be non-pathogenic to humans. conventional microbiological detection methods are very time consuming. the polymerase chain reaction (pcr) is one of the most promising techniques for rapid detection of micro-organisms in food products. we have developed a pcr assay, specific for l. monocytogenes, based on the gene encoding an aminopeptidase, which previo ... | 1999 | 10208803 |
| potential of conjugal transfer as a strategy for the introduction of recombinant genetic material into strains of lactobacillus helveticus | cointegrates generated between a plasmid pip501 deletion derivative (pva797) and nonconjugative shuttle vector psa3 were confirmed as capable of exconjugation from lactococci into a range of strains of lactobacillus helveticus with the concomitant expression of a recombinant gene. the plasmid cointegrate that was formed appeared to be segregationally stable at 37 degrees c in some host strains. in all strains, however, the plasmid became increasingly unstable as the incubation temperature was ra ... | 1999 | 10223978 |
| sensitivity of staphylococcus aureus and lactobacillus helveticus in ovine milk subjected to high hydrostatic pressure. | ovine milk, standardized to 6% fat, was inoculated with staphylococcus aureus cect 534 and lactobacillus helveticus cect 414 at a concentration of 10(7) cfu/ml and treated by high hydrostatic pressure. treatments consisted of combinations of pressure (200, 300, 400, 450, and 500 mpa), temperature (2, 10, 25, and 50 degrees c), and time (5, 10, and 15 min). staphylococcus aureus was highly resistant to pressure; only pressurizations at 50 degrees c of 500 mpa for 15 min achieved reductions of > o ... | 1999 | 10386295 |
| purification and characterization of an antihypertensive peptide from a yogurt-like product fermented by lactobacillus helveticus cpn4. | whey peptides in a yogurt-like product fermented by lactobacillus helveticus cpn4 were fractionated by a sep-pak c-18 cartridge followed by two-step reverse-phase hplc. the antihypertensive activity was measured by systolic blood pressure in spontaneously hypertensive rats after oral administration of each fraction. five major peptides in the final fraction were further purified by reverse-phase hplc and were measured for these antihypertensive activities in spontaneously hypertensive rats. the ... | 1999 | 10416158 |
| genetic characterization of a cell envelope-associated proteinase from lactobacillus helveticus cnrz32. | a cell envelope-associated proteinase gene (prth) was identified in lactobacillus helveticus cnrz32. the prth gene encodes a protein of 1,849 amino acids and with a predicted molecular mass of 204 kda. the deduced amino acid sequence of the prth product has significant identity (45%) to that of the lactococcal prtp proteinases. southern blot analysis indicates that prth is not broadly distributed within l. helveticus. a prth deletion mutant of cnrz32 was constructed to evaluate the physiological ... | 1999 | 10419958 |
| inactivation of lactobacillus helveticus bacteriophages by thermal and chemical treatments. | the effect of several biocides and thermal treatments on the viability of four lactobacillus helveticus phages was investigated. times to achieve 99% inactivation of phages at 63 degrees c and 72 degrees c in three suspension media were calculated. the three suspension media were tris magnesium gelatin buffer (10 mm tris-hcl, 10 mm mgso4, and 0.1% wt/vol gelatin), reconstituted skim milk sterile reconstituted commercial nonfat dry skim milk, and man rogosa sharpe broth. the thermal resistance de ... | 1999 | 10456743 |
| survival of lactobacillus helveticus entrapped in ca-alginate in relation to water content, storage and rehydration. | lactobacillus helveticus cnrz 303 entrapped in ca-alginate gel beads was investigated for improved survival and stability during fluidized-bed drying, storage and rehydration. addition of protective solutes was very important. studies of the conditions showed that inactivation of entrapped l. helveticus started when the water content exceeded 0.3-0.4 g h2o (g dry wt)-1 for adonitol, glycerol and reconstituted non fat milk solids (nfsm). with ringer's solution (control) and betaine, the fall in v ... | 1999 | 10510483 |
| multi-domain, cell-envelope proteinases of lactic acid bacteria. | the multi-domain, cell-envelope proteinases encoded by the genes prtb of lactobacillus delbrueckii subsp. bulgaricus, prth of lactobacillus helveticus, prtp of lactococcus lactis, scpa of streptococcus pyogenes and csp of streptococcus agalactiae have been compared using multiple sequence alignment, secondary structure prediction and database homology searching methods. this comparative analysis has led to the prediction of a number of different domains in these cell-envelope proteinases, and th ... | 1999 | 10532376 |
| peptidases and amino acid catabolism in lactic acid bacteria. | the conversion of peptides to free amino acids and their subsequent utilization is a central metabolic activity in prokaryotes. at least 16 peptidases from lactic acid bacteria (lab) have been characterized biochemically and/or genetically. among lab, the peptidase systems of lactobacillus helveticus and lactococcus lactis have been examined in greatest detail. while there are homologous enzymes common to both systems, significant differences exist in the peptidase complement of these organisms. ... | 1999 | 10532381 |
| effect of protective solutes on leakage from and survival of immobilized lactobacillus subjected to drying, storage and rehydration | when lactic acid bacteria are used industrially as fermentation starters it is important to obtain stable and highly viable bacterial cultures. six strains of lactobacillus encapsulated in ca-alginate gel beads were investigated to determine whether dehydration, storage and rehydration may inflict injury. a negative relationship between leakage of lactate dehydrogenase and survival rates was found. mesophilic lactobacilli showed only negligible leakage compared with thermophilic strains when deh ... | 1999 | 10540246 |
| complete sequence of plasmid plh1 from lactobacillus helveticus atcc15009: analysis reveals the presence of regions homologous to other native plasmids from the host strain. | the complete sequence for plasmid plh1 from lactobacillus helveticus atcc15009 has been determined. analysis of the 19,360-bp primary sequence revealed a putative replication origin and initiation protein, information that could provide the basis for the construction of cloning vectors for l. helveticus. evidence that plh1 is theta-replicating could be deduced from the plasmid size, from the homology to the replication protein of the bacillus natto theta-replicating plasmid pls32, and from the i ... | 1999 | 10545264 |
| growth of facultatively heterofermentative lactobacilli on starter cell suspensions. | the growth of facultatively heterofermentative lactobacilli (fhl) on cell suspensions of the homofermentative lactobacillus helveticus was investigated. osmotic lysis of l. helveticus led to a significant increase of ribose. it decreased steadily in parallel with the growth of fhl, strongly suggesting that the bacteria used ribose as a growth substrate. | 1999 | 10584024 |
| x-prolyl dipeptidyl aminopeptidase gene (pepx) is part of the glnra operon in lactobacillus rhamnosus. | a peptidase gene expressing x-prolyl dipeptidyl aminopeptidase (pepx) activity was cloned from lactobacillus rhamnosus 1/6 by using the chromogenic substrate l-glycyl-l-prolyl-beta-naphthylamide for screening of a genomic library in escherichia coli. the nucleotide sequence of a 3.5-kb hindiii fragment expressing the peptidase activity revealed one complete open reading frame (orf) of 2,391 nucleotides. the 797-amino-acid protein encoded by this orf was shown to be 40, 39, and 36% identical with ... | 2000 | 10613874 |
| purification and molecular characterization of a tripeptidase (pept) from lactobacillus helveticus. | a tripeptidase (pept) from a thermophilic dairy starter strain of lactobacillus helveticus was purified by four chromatographic steps. pept appeared to be a trimeric metallopeptidase with a molecular mass of 150 kda. pept exhibited maximum activity against hydrophobic tripeptides, with the highest activity for met-gly-gly (k(m), 2.6 mm; v(max), 80.2 micromol. min(-1). microg(-1)). some of the hydrophobic dipeptides were slowly hydrolyzed, distinguishing the lactobacillus pept from its counterpar ... | 2000 | 10653753 |
| biodegradability of food-associated extracellular polysaccharides. | exopolysaccharides (epss) produced by lactic acid bacteria, which are common in fermented foods, are claimed to have various beneficial physiological effects on humans. although the biodegradability of epss is important in relation to the bioactive properties, knowledge on this topic is limited. therefore, the biodegradability of eight epss, six of which were produced by lactic acid bacteria, was compared with microorganisms from human feces or soil. eps-degradation was determined from the decre ... | 2000 | 10679053 |
| nucleotide sequence analysis of the lactococcal eps plasmid pnz4000. | the complete 42180-bp nucleotide sequence of the mobilization plasmid pnz4000, coding for exopolysaccharide (eps) production in lactococcus lactis, was determined. this plasmid contains a region involved in eps biosynthesis, four functional replicons, a region containing mobilization genes, and three origin of transfer (orit) sequences. sequences identical to these orit sequences were also found on two other lactococcal plasmids and a plasmid from lactobacillus helveticus. several complete and p ... | 2000 | 10686131 |
| comparison of simple neural networks and nonlinear regression models for descriptive modeling of lactobacillus helveticus growth in ph-controlled batch cultures. | a set of 20 lactobacillus helveticus growth curves was obtained from ph-controlled batch cultures with different ph setpoints, whey permeate and yeast extract concentrations. to find the best descriptive model of the biomass concentration versus time (y = x(t)) growth curve, fitting results of a large number of models were compared with statistical and approximate methods. models studied included simple neural networks, reparameterized logistic, gompertz, richards, schnute, weibull, and morgan-m ... | 2000 | 10713218 |
| molecular diversity within lactobacillus helveticus as revealed by genotypic characterization. | lactobacillus helveticus is a homofermentative thermophilic lactic acid bacterium that is used in the manufacture of swiss type and long-ripened italian cheeses, such as emmental, grana, and provolone cheeses. substantial differences in several technologically important characteristics are found among l. helveticus strains isolated from natural dairy starter cultures. in the present study we investigated the genotypic diversity of 74 strains isolated from different dairy cultures used for manufa ... | 2000 | 10742197 |
| high pressure inactivation of microorganisms inoculated into ovine milk of different fat contents. | high hydrostatic pressure inactivation of escherichia coli, pseudomonas fluorescens, listeria innocua, staphylococcus aureus, and lactobacillus helveticus were studied. these microorganisms were inoculated at a concentration between 10(7) and 10(8) cfu/ml in ringer solution and in ovine milk adjusted to 0, 6, and 50% fat content to evaluate the baroprotective effect of fat content on inactivation of microorganisms. treatments of pressurization consisted of combinations of pressure (100 to 500 mp ... | 2000 | 10791782 |
| characterization of an arylesterase from lactobacillus helveticus cnrz32. | an esterase gene (esta) was isolated from a previously constructed genomic library of lactobacillus helveticus cnrz32. the esta gene consisted of a 558 bp open reading frame encoding a putative peptide of 21.3 kda. protein sequence homology searches using blast revealed that esta had low amino acid sequence identity with the serine-dependent arylesterases tesi (24%) and etpa (26%) from escherichia coli and vibrio mimicus, respectively. a recombinant esta fusion protein containing a c-terminal si ... | 2000 | 10792515 |
| surface of lactic acid bacteria: relationships between chemical composition and physicochemical properties. | the surface chemical composition and physicochemical properties (hydrophobicity and zeta potential) of two lactic acid bacteria, lactococcus lactis subsp. lactis bv. diacetilactis and lactobacillus helveticus, have been investigated using cells harvested in exponential or stationary growth phase. the surface composition determined by x-ray photoelectron spectroscopy (xps) was converted into a molecular composition in terms of proteins, polysaccharides, and hydrocarbonlike compounds. the concentr ... | 2000 | 10831437 |
| autolysis and related proteolysis in swiss cheese for two lactobacillus helveticus strains. | intracellular peptidases of lactobacillus helveticus may play a major role in the proteolysis of swiss cheeses, provided that they are released through bacterial lysis. experimental swiss cheeses were manufactured on a small scale from thermized and microfiltered milk using as starters (in addition to streptococcus thermophilus and propionibacterium freudenreichii) one of two lb. helveticus strains, itglh1 and itglh77, which undergo lysis to different extents in vitro. all the cheeses were bioch ... | 2000 | 10840680 |
| lactobacillus fornicalis sp. nov., isolated from the posterior fornix of the human vagina. | twelve strains isolated from the posterior fornix fluid of the human vagina were identified as lactobacillus johnsonii, lactobacillus acidophilus, lactobacillus gallinarum and lactobacillus crispatus based on numerical analyses of total soluble cell protein profiles and randomly amplified polymorphic dna (rapd)-pcr banding patterns. five strains grouped with the type strains of lactobacillus gasseri (dsm 20077t) and lactobacillus jensenii (dsm 20557t) at r > or = 0.83 in one protein profile clus ... | 2000 | 10843070 |
| structural elucidation of the viscous exopolysaccharide produced by lactobacillus helveticus lb161. | a viscous extracellular polysaccharide produced by lactobacillus helveticus lb161 isolated from raw milk has been investigated. sugar and methylation analysis, and 1h and 13c nmr spectroscopy revealed that the polysaccharide is composed of a heptasaccharide repeating unit. the sequence of sugar residues was determined by use of two-dimensional nuclear overhauser effect spectroscopy and heteronuclear multiple bond connectivity experiments. the structure of the repeating unit of the exopolysacchar ... | 2000 | 10877094 |
| molecular cloning and sequence analysis of a gene encoding an extracellular proteinase from lactobacillus helveticus cp790. | a 2.6-kilobase haeiii dna fragment corresponding to an extracellular proteinase gene (prty) was cloned from chromosomal dna of lactobacillus helveticus cp790 in escherichia coli using a pkk223-3 vector. the transformant expressed a 48-kda protein that reacts with monoclonal antibodies specific to the proteinase and seemed to be a pre-proproteinase, but had no proteolytic activity. about 1.6 kilobases of the 2.6-kilobase dna fragment, which contained the complete gene for the proteinase was seque ... | 2000 | 10923793 |
| s-layer gene as a molecular marker for identification of lactobacillus helveticus. | the paper describes two methods that allow rapid and accurate identification of lactobacillus helveticus strains based on the nucleotide sequence of the gene coding for the surface layer (s-layer) protein. the first method is based on a polymerase chain reaction amplification using primers targeting a specific fragment of the s-layer gene. the second method involved a portion of the s-layer gene of l. helveticus as a probe in a hybridisation test. the specificity of these protocols was checked f ... | 2000 | 10930751 |
| expression of the phospho-beta-glycosidase arbz from lactobacillus delbrueckii subsp. lactis in lactobacillus helveticus: substrate induction and catabolite repression. | arbz from lactobacillus delbrueckii subsp. lactis was previously shown to enable utilization of the beta-glucoside arbutin by escherichia coli. the arbz gene was cloned and expressed in the industrially used beta-glucoside-negative strain lactobacillus helveticus 3036(62). the transformants were able to ferment not only arbutin, but also cellobiose, salicin and methyl-beta-glucoside (mbetaglc). cleavage of beta-glucosides by the transformants depended on the integrity of the cytoplasmic membrane ... | 2000 | 10931898 |
| characterization of natural isolates of lactobacillus strains to be used as starter cultures in dairy fermentation. | the technological relevant characteristics of five homofermentative lactobacilli strains, isolated from natural fermented hard cheeses, were studied. isolates crl 581 and crl 654, from argentinian artesanal hard cheeses, and isolates crl 1177, crl 1178, and crl 1179, from italian grana cheeses, were identified as lactobacillus delbrueckii subsp. lactis and lactobacillus helveticus, respectively, by physiological and biochemical tests, sds-page of whole-cell proteins and sequencing of the variabl ... | 2000 | 10946835 |
| metabolic engineering of lactobacillus helveticus cnrz32 for production of pure l-(+)-lactic acid. | expression of d-(-)-lactate dehydrogenase (d-ldh) and l-(+)-ldh genes (ldhd and ldhl, respectively) and production of d-(-)- and l-(+)-lactic acid were studied in lactobacillus helveticus cnrz32. in order to develop a host for production of pure l-(+)-isomer of lactic acid, two ldhd-negative l. helveticus cnrz32 strains were constructed using gene replacement. one of the strains was constructed by deleting the promoter region of the ldhd gene, and the other was constructed by replacing the struc ... | 2000 | 10966398 |
| ripening of cheddar cheese with added attenuated adjunct cultures of lactobacilli. | we made milled curd cheddar cheese with lactococcus starter and an adjunct culture of lactobacillus helveticus i or lactobacillus casei t subjected to different attenuation treatments: freeze shocking (fs), heat shocking (hs), or spray drying (sd). proteolysis during cheese ripening (0 to 6 mo), measured by urea-page and water-soluble nitrogen, indicated only minor differences between control and most adjunct-treated cheeses. however, there were significant differences in the effect of lactobaci ... | 2000 | 10984143 |
| influence of capsular and ropy exopolysaccharide-producing streptococcus thermophilus on mozzarella cheese and cheese whey. | we investigated the effect of capsular and ropy exopolysaccharide-producing streptococcus thermophilus starter bacteria on mozzarella cheese functionality and whey viscosity. mozzarella cheeses were manufactured with lactobacillus helveticus lh100 paired with one of four s. thermophilus strains: mr-1c, a bacterium that produces a capsular exopolysaccharide; mtc360, a strain that secretes a ropy exopolysaccharide; tao61, a nonexopolysaccharide-producing commercial cheese starter; and dm10, a none ... | 2000 | 11003223 |
| a lactobacillus helveticus plasmid detects restriction fragment length polymorphism in different bacterial species. | a small cryptic lactobacillus helveticus plasmid, plbl4, was able to reveal restriction fragment length polymorphism in different bacterial species including lactobacillus species, bacillus species, and escherichia coli when used as a dna probe. the observed polymorphism was a result of the combined hybridization of several microsatellite sequences. the 6-bp sequence (ttgttt) was repeated 12 times, seven of which were concentrated within the region between 1791 and 1997 bp of the plasmid sequenc ... | 2000 | 11034301 |
| nutritional requirements and nitrogen-dependent regulation of proteinase activity of lactobacillus helveticus crl 1062. | the nutritional requirements of lactobacillus helveticus crl 1062 were determined with a simplified chemically defined medium (scdm) and compared with those of l. helveticus crl 974 (atcc 15009). both strains were found to be prototrophic for alanine, glycine, asparagine, glutamine, and cysteine. in addition, crl 1062 also showed prototrophy for lysine and serine. the microorganisms also required riboflavin, calcium pantothenate, pyridoxal, nicotinic acid, and uracil for growth in liquid scdm. t ... | 2000 | 11097908 |
| hydrolysis of sequenced beta-casein peptides provides new insight into peptidase activity from thermophilic lactic acid bacteria and highlights intrinsic resistance of phosphopeptides. | the peptidases of thermophilic lactic acid bacteria have a key role in the proteolysis of swiss cheeses during warm room ripening. to compare their peptidase activities toward a dairy substrate, a tryptic/chymotryptic hydrolysate of purified beta-casein was used. thirty-four peptides from 3 to 35 amino acids, including three phosphorylated peptides, constitute the beta-casein hydrolysate, as shown by tandem mass spectrometry. cell extracts prepared from lactobacillus helveticus itg lh1, itg lh77 ... | 2000 | 11097915 |
| structure of a viscous exopolysaccharide produced by lactobacillus helveticus k16. | a viscous extracellular polysaccharide produced by lactobacillus helveticus k16 has been investigated. sugar and methylation analysis, 1h and 13c nmr spectroscopy revealed that the polysaccharide is composed of a hexasaccharide repeating unit. the sequence of sugar residues was determined by use of two-dimensional nuclear overhauser effect spectroscopy and heteronuclear multiple bond connectivity experiments. the structure of the repeating unit of the exopolysaccharide from l. helveticus k16 is ... | 2000 | 11117331 |
| the s-layer protein of lactobacillus acidophilus atcc 4356: identification and characterisation of domains responsible for s-protein assembly and cell wall binding. | lactobacillus acidophilus, like many other bacteria, harbors a surface layer consisting of a protein (s(a)-protein) of 43 kda. s(a)-protein could be readily extracted and crystallized in vitro into large crystalline patches on lipid monolayers with a net negative charge but not on lipids with a net neutral charge. reconstruction of the s-layer from crystals grown on dioleoylphosphatidylserine indicated an oblique lattice with unit cell dimensions (a=118 a; b=53 a, and gamma=102 degrees ) resembl ... | 2001 | 11124903 |
| molecular cloning and expression of the nucleoside deoxyribosyltransferase-ii gene from lactobacillus helveticus. | nucleoside deoxyribosyltransferase-ii, which catalyzes transfer of glycosyl residues from a donor deoxynucleoside to an acceptor base, was purified from lactobacillus helveticus and its gene was cloned. analysis of the nucleotide sequence showed the presence of a 474-nucleotide open reading frame encoding a protein of 158 amino acids with a molecular weight of 18,317. the active enzyme can be produced in large quantities in e. coli cells using the cloned gene. | 2000 | 11129605 |
| survival of lactobacillus helveticus strain cp53 in the human gastrointestinal tract. | a strain of lactobacillus helveticus carrying the cryptic plasmid pcp53 was used for a detailed analysis of the survival and persistence of this organism in the faeces of volunteers administered oral doses of the strain. the cp53 strain had high affinity for caco-2 cells, but displayed low bile acid resistance in vitro. rifampicin-resistant colonies could be reisolated from the faeces of four of seven subjects fed with the rifampicin-resistant cp53 derivative strain. moreover, the recovery of ce ... | 2001 | 11169053 |
| molecular discrimination of lactobacilli used as starter and probiotic cultures by amplified ribosomal dna restriction analysis. | lactic acid bacteria such as lactobacillus helveticus, l. delbrueckii subsp. delbrueckii, l. delbrueckii subsp. lactis, l. delbrueckii subsp. bulgaricus, l. acidophilus, and l. casei related taxa which are widely used as starter or probiotic cultures can be identified by amplified ribosomal dna restriction analysis (ardra). the genetic discrimination of the related species belonging to these groups was first obtained by pcr amplifications by using group-specific or species-specific 16s rdna prim ... | 2001 | 11178730 |
| characterization by molecular cloning and sequencing of the gene encoding an aminopeptidase from listeria monocytogenes. | the pepc gene of listeria monocytogenes encodes aminopeptidase c that is predicted to share 72% amino acid sequence similarity and 53% sequence identity with the cysteine aminopeptidase pepc from lactococcus lactis. the gene product also shows strong similarity to aminopeptidase c from streptococcus thermophilus and lactobacillus helveticus, and to a cysteine proteinase/bleomycin hydrolase from saccharomyces cerevisiae. the enzyme from l. monocytogenes displayed broad n-terminal hydrolytic activ ... | 2000 | 11204766 |
| expression of six peptidases from lactobacillus helveticus in lactococcus lactis. | for development of novel starter strains with improved proteolytic properties, the ability of lactococcus lactis to produce lactobacillus helveticus aminopeptidase n (pepn), aminopeptidase c (pepc), x-prolyl dipeptidyl aminopeptidase (pepx), proline iminopeptidase (pepi), prolinase (pepr), and dipeptidase (pepd) was studied by introducing the genes encoding these enzymes into l. lactis mg1363 and its derivatives. according to northern analyses and enzyme activity measurements, the l. helveticus ... | 2001 | 11229915 |
| isolation and characterization of a slowly milk-coagulating variant of lactobacillus helveticus deficient in purine biosynthesis. | a slowly milk-coagulating variant (fmc(-)) of lactobacillus helveticus crl 1062, designated s1, was isolated and characterized. strain s1 possessed all the known essential components required to utilize casein as a nitrogen source, which include functional proteinase and peptidase activities as well as functional amino acid, di- and tripeptide, and oligopeptide transport systems. the amino acid requirements of strain s1 were similar to those of the parental strain. however, on a purine-free, che ... | 2001 | 11282642 |
| specific identification of lactobacillus helveticus by pcr with pepc, pepn and htra targeted primers. | specific regions in three genes coding for aminopeptidases c and n, and a trypsin-like serine protease were selected as species-specific primer sequences for rapid and reliable identification of lactobacillus helveticus strains. the pcr procedures carried out gave specific 524-, 726- and 918-bp amplificates, with dna isolated from l. helveticus. no pcr product was generated for closely related bacteria. the amplification products were also screened for their species specificity in dot blot hybri ... | 2001 | 11325558 |
| tyrosine and phenylalanine catabolism by lactobacillus cheese flavor adjuncts. | bacterial metabolism of tyr and phe has been associated with the formation of aromatic compounds that impart barny-utensil and floral off-flavors in cheese. in an effort to identify possible mechanisms for the origin of these compounds in cheddar cheese, we investigated tyr and phe catabolism by lactobacillus casei and lactobacillus helveticus cheese flavor adjuncts under simulated cheddar cheese-ripening (ph 5.2, 4% nacl, 15 degrees c, no sugar) conditions. enzyme assays of cell-free extracts i ... | 2001 | 11384026 |
| batch cultures of supplemented whey permeate using lactobacillus helveticus: unstructured model for biomass formation, substrate consumption and lactic acid production. | the luedeking and piret expression can not account for the cessation of production observed at the end of batch; so an empiric term has been previously added to this equation which accounted in a global way for possible substrate limitations. in the model developed in this work, a carbon substrate limitation appeared explicitly in the production expression. assuming a sigmoidal variation with time of specific growth rate previously validated, the new production model matched well the entire expe ... | 2001 | 11397465 |
| partial characterization of a bacteriocin produced by lactobacillus helveticus. | to investigate the antimicrobial activity of a strain of lactobacillus helveticus. | 2001 | 11472525 |
| alteration in cellular fatty acid composition as a response to salt, acid, oxidative and thermal stresses in lactobacillus helveticus. | the fundamental question in this study is concerned with whether the increase of unsaturated fatty acids in the cell membrane is a general response of certain thermotolerant strains or species when exposed to superoptimal temperatures, and in combination with other stresses, especially oxidative stress. a strain of lactobacillus helveticus, a species widely used as a starter in the dairy industry and able to tolerate high temperature and nacl concentrations as well as acidic conditions, was chos ... | 2001 | 11496002 |
| conversion of amino acids into aroma compounds by cell-free extracts of lactobacillus helveticus. | lactobacillus helveticus is an essential starter in swiss-type cheeses such as emmental. this study was to determine whether cell-free extracts of lact. helveticus were able to convert free amino acids into neutral volatile aroma compounds at the ph and temperature occurring in cheese. | 2001 | 11556904 |
| influence of adjunct cultures on ripening of reduced fat edam cheeses. | the influence of four adjunct cultures [brevibacterium linens (bl2), lactococcus lactis ssp. diacetylactis, lactobacillus helveticus (lh212), and lactobacillus reuteri (atcc 23272)] on chemical and sensory characteristics of reduced fat edam cheese was studied. the aminopeptidase activity of lactococcus lactis ssp. diacetylactis was higher than that of lactobacillus helveticus, lactobacillus reuteri, and brevibacterium linens, respectively. mean percent fat and moisture contents of reduced fat c ... | 2001 | 11699441 |
| heterofermentative pattern and exopolysaccharide production by lactobacillus helveticus atcc 15807 in response to environmental ph. | the objective of this work was to evaluate the fermentation pattern of and the exopolysaccharide (eps) production by lactobacillus helveticus atcc 15807 in milk batch cultures under controlled ph (4.5, 5.0 and 6.2). | 2001 | 11722662 |
| dna cloning in lactobacillus helveticus by the exconjugation of recombinant mob-containing plasmid constructs from strains of transformable lactic acid bacteria. | a system developed for the genetic transfer of plasmids between strains of nontransformable bacteria (p. langella, y. le loir, s. d. ehrlich and a. gruss, 1993, j. bacteriol., 175, 5806-5813) by the specific inclusion of a mobilization (mob) region into a nonconjugative shuttle vector was used successfully to deliver the genetic determinants for beta-glucanase, beta-glucuronidase, and green fluorescent protein to lactobacillus helveticus. expression of two of the genes could be detected in the n ... | 2001 | 11735368 |
| modeling of the structure in aqueous solution of the exopolysaccharide produced by lactobacillus helveticus 766. | a method is described for constructing a conformational model in water of a heteropolysaccharide built up from repeating units, and is applied to the exopolysaccharide produced by lactobacillus helveticus 766. the molecular modeling method is based on energy minima, obtained from molecular mechanics calculations of each of the constituting disaccharide fragments of the repeating unit in vacuo, as starting points. subsequently, adaptive umbrella sampling of the potential of mean force is applied ... | 2002 | 11754349 |
| identification of a gene cluster for the mevalonate pathway in lactobacillus helveticus. | three lactobacillus helveticus 53/7 genes essential for the biosynthesis of isopentenyl diphosphate and the gene coding for a putative carotenoid biosynthesis protein were for the first time identified from lactic acid bacteria. the deduced amino acid sequences of the mevalonate pathway gene products share significant identity with corresponding proteins of a few gram-positive cocci and streptomyces species. | 2001 | 11762194 |
| extracellular arginine aminopeptidase from streptococcus gordonii fss2. | streptococcus gordonii is a primary etiological agent in the development of subacute bacterial endocarditis (sbe), producing thrombus formation and tissue damage on the surfaces of heart valves. this is ironic, considering its normal role as a benign inhabitant of the oral microflora. however, strain fss2 of s. gordonii has been found to produce several extracellular aminopeptidase- and fibrinogen-degrading activities during growth in a ph-controlled batch culture. in this report, we describe th ... | 2002 | 11796618 |
| functional cloning, heterologous expression, and purification of two different n-deoxyribosyltransferases from lactobacillus helveticus. | lactobacillus helveticus contains two types of n-deoxyribosyltransferases: drtase i catalyzes the transfer of 2'-deoxyribose between purine bases exclusively whereas drtase ii is able to transfer the 2'-deoxyribose between two pyrimidine or between pyrimidine and purine bases. an escherichia coli strain, auxotrophic for guanine and unable to use deoxyguanosine as source of guanine, was constructed to clone the corresponding genes. by screening a genomic bank for the production of guanine, the l. ... | 2002 | 11836245 |
| an x-prolyl dipeptidyl aminopeptidase from lactococcus lactis: cloning, expression in escherichia coli, and application for removal of n-terminal pro-pro from recombinant proteins. | a novel pepx gene was cloned from isolated dna of lactococcus lactis by pcr. the deduced amino acid sequence of the 89-kda protein showed 94, 93, 65, and 44% identity with the pepx protein from lactococcus lactis subsp. cremoris, lactococcus lactis subsp. lactis, lactobacillus delbruecki subsp. bulgaricus, and lactobacillus helveticus, respectively, and contained a serine protease g-k-s-y-l-g consensus motif. the pepx gene has been cloned into pet17b and was expressed at a high level in escheric ... | 2002 | 11922771 |
| stability of species composition of fecal bifidobacteria in human subjects during fermented milk administration. | bifidobacteria play important roles in human health. however, the influence of exogenous factors on species composition of fecal bifidobacteria is still unclear. the objective of this study was to investigate the effects of fermented milk administration on the species composition of fecal bifidobacteria by molecular biological methods. fermented milk containing lactobacillus helveticus was given to seven healthy subjects, and the probiotic effect on human fecal microflora was demonstrated as a s ... | 2002 | 11927989 |
| immunomodulating effects of milks fermented by lactobacillus helveticus and its non-proteolytic variant. | the effect of milks fermented by lactobacillus helveticus and its non-proteolytic variant on mucosal and tumoral immunity was studied. milks fermented by lb. helveticus wild type or its non-proteolytic variant were administered orally to mice for different periods (3, 5 and 7 d). the immune response was assessed by analysing the activity of the peritoneal macrophages, the number of cells secreting iga associated with the gut-associated lymphoid tissue and with the bronchial-associated lymphoid t ... | 2001 | 11928956 |
| lactic acid bacteria and yeasts in kefir grains and kefir made from them. | in an investigation of the changes in the microflora along the pathway: kefir grains (a)-->kefir made from kefir grains (b)-->kefir made from kefir as inoculum (c), the following species of lactic acid bacteria (83-90%) of the microbial count in the grains) were identified: lactococcus lactis subsp. lactis, streptococcus thermophilus, lactobacillus delbrueckii subsp. bulgaricus, lactobacillus helveticus, lactobacillus casei subsp. pseudoplantarum and lactobacillus brevis. yeasts (10-17%) identif ... | 2002 | 11938463 |
| autolytic phenotype of lactococcus lactis strains isolated from traditional tunisian dairy products. | to evaluate the autolytic properties of lactococcus lactis strains isolated from artisan tunisian dairy products, their peptidoglycan hydrolase content and their activity spectrum. | 2002 | 11972683 |
| recombinant lactococcus starters as a potential source of additional peptidolytic activity in cheese ripening. | the aim of this study was to modulate the lactococcal proteolytic system for enhancement of the cheese ripening process. | 2002 | 12010556 |
| a continuous lactic acid production system using an immobilized packed bed of lactobacillus helveticus. | a 5 l packed bed bioreactor was used to study the effect of initial lactose concentration and hydraulic retention time (hrt) on cell growth, lactose utilization and lactic acid production. up to 95% of the initial lactose concentration was utilized at longer hrts (30-36 h). the study showed that lactic acid production increased with increases in hrt (12-36 h) and initial lactose concentrations. the highest lactic acid production rate (3.90 g l(-1) h(-1)) was obtained with an initial lactose conc ... | 2002 | 12021789 |
| diversity in specificity of the extracellular proteinases in lactobacillus helveticus and lactobacillus delbrueckii subsp. bulgaricus. | aims: to investigate the diversity in specificity of cell-bound extracellular proteinases in lactobacillus helveticus and lactobacillus delbrueckii subsp. bulgaricus. methods and results: hplc analysis of whole-cell preparations of 14 lact. delbrueckii subsp. bulgaricus and eight lact. helveticus strains incubated with alpha (s1)-casein (f 1-23) detected at least six distinct proteolytic patterns. differences between groups were found in both the primary and secondary specificity toward alpha(s1 ... | 2002 | 12028429 |
| use of pcr-based methods and pfge for typing and monitoring homofermentative lactobacilli during comté cheese ripening. | this study investigated the genotypic characteristics of selected and wild homofermentative thermophilic lactobacilli strains during ripening of comté cheeses, made into two cheese plants. both amplification and restriction analysis of the 16s rrna gene (pcr-ardra) and classical biochemical tests were used to identify isolates. diversity within homofermentative lactobacilli was not found in their species composition since the same two species lactobacillus helveticus and l. delbrueckii susbp. la ... | 2002 | 12038575 |
| a polyphasic approach to highlight genotypic and phenotypic diversities of lactobacillus helveticus strains isolated from dairy starter cultures and cheeses. | in the present work, 67 strains of lactobacillus helveticus isolated from whey starter cultures and cheeses were identified and grouped by genotypic and phenotypic methods. strains were identified by sugar fermentation pattern, by cell-wall protein profile, and by probe hybridisation. phenotypic diversity was evaluated by a chemometric model taking into account biochemical characteristics (i.e. acidifying and peptidase activities) of technological interest. genotypic diversity was evidenced by r ... | 2002 | 12047105 |
| domain closure, substrate specificity and catalysis of d-lactate dehydrogenase from lactobacillus bulgaricus. | nad-dependent lactobacillus bulgaricus d-lactate dehydrogenase (d-ldhb) catalyses the reversible conversion of pyruvate into d-lactate. crystals of d-ldhb complexed with nadh were grown and x-ray data collected to 2.2 a. the structure of d-ldhb was solved by molecular replacement using the dimeric lactobacillus helveticus d-ldh as a model and was refined to an r-factor of 20.7%. the two subunits of the enzyme display strong asymmetry due to different crystal environments. the opening angles of t ... | 2002 | 12054772 |
| lactobacillus helveticus glycosyltransferases: from genes to carbohydrate synthesis. | bioactive carbohydrates are crucial in mediating essential biological processes, and their biosynthesis is an essential aspect to develop for a global view of their biological functions. lactic acid bacteria display an array of diverse and complex carbohydrates and, therefore, are of particular interest. here we present the identification of a novel exocellular polysaccharide structure and the corresponding gene cluster from lactobacillus helveticus ncc2745. the development of a glycosyltransfer ... | 2002 | 12070074 |
| cardiovascular effects of fermented milk containing angiotensin-converting enzyme inhibitors evaluated in permanently catheterized, spontaneously hypertensive rats. | in this study, two strains of lactobacillus helveticus were used to produce fermented milk rich in angiotensin-converting enzyme (ace) inhibitors. in vitro tests revealed that the two milks contained competitive inhibitors of ace in amounts comparable to what has been obtained in previously reported studies. the two milks were administered by gavage to spontaneously hypertensive rats that had had a permanent aortic catheter inserted through the left arteria carotis, and mean arterial blood press ... | 2002 | 12089043 |
| rapid and sensitive detection method of a bacterium by using a gfp reporter phage. | a rapid, sensitive, and convenient method for detecting a specific bacterium was developed by using a gfp phage. here we describe a model system that utilizes the temperate escherichia coli-restricted bacteriophage lambda, which was genetically modified to express a reporter gene for gfp to identify the colon bacillus e. coli in the specimen. e. coli infected with gfp phage was detected by gfp fluorescence after 4-6 hr of incubation. the results show that a few bacteria in a specimen can be dete ... | 2002 | 12153113 |
| a food-grade cloning vector for lactic acid bacteria based on the nisin immunity gene nisi. | a new food-grade cloning vector for lactic acid bacteria was constructed using the nisin immunity gene nisi as a selection marker. the food-grade plasmid, pleb 590, was constructed entirely of lactococcal dna: the psh 71 replicon, the nisi gene, and the constitutive promoter p45 for nisi expression. electroporation into lactococcus lactis mg 1614 with 60 international units (iu) nisin/ml selection yielded approximately 10(5) transformants/ micro g dna. mg 1614 carrying pleb 590 was shown to be a ... | 2002 | 12172611 |
| bacterial membrane injuries induced by lactacin f and nisin. | the combined action of nisin and lactacin f, two bacteriocins produced by lactic acid bacteria, is additive. in this report, the basis of this effect is examined. channels formed by lactacin f were studied by experiments using planar lipid bilayers, and bactericidal effects were analyzed by flow cytometry. lactacin f produced pores with a conductance of 1 ns in black lipid bilayers in 1 mm kci at 10 mv at 20 degrees c. pore formation was strongly dependent on voltage. although lactacin f formed ... | 2002 | 12180783 |
| application of vitamin b(12)-targeting site on lactobacillus helveticus b-1 to vitamin b(12) assay by chemiluminescence method. | lactobacillus helveticus b-1 is assumed to have a vitamin b(12)-targeting (or b(12)-binding) site on the cells, since the binding reaction of vitamin b(12) with l. helveticus b-1 cells proceeded instantly and quantitatively. this reaction is specific to complete b(12) compounds, cobalamins, and can be used for a vitamin b(12) assay method by chemiluminescence. the calibration graph was linear from 0.1 to 10.0 ng/ml. the b(12) contents in oyster and sardine were 75.9 and 39.4 microg/100g, respect ... | 2002 | 12234457 |
| differentiation of lactobacillus helveticus, lactobacillus delbrueckii subsp bulgaricus, subsp lactis and subsp delbrueckii using physiological and genetic tools and reclassification of some strains from the atcc collection. | several physiological tests of glucose metabolism and genetic tools including species specific probes and 16s rdna sequences were used to identify strains of l. helveticus and the group of l. delbrueckii with its three subspecies lactis, bulgaricus, and delbrueckii. these species are important for the milk industry as fermenting lactic acid bacteria. the identification procedure was applied to the different strains of these species available from the atcc collection and allowed to reclassify par ... | 2002 | 12353877 |
| anti-hypertensive activity of fermented dairy products containing biogenic peptides. | a considerable amount of research has been conducted to study the health benefits of fermented milks. one possible mechanism for the beneficial effects is the involvement of biogenic compounds, which are produced by the action of microorganisms and make the products directly beneficial without the need for live bacteria. research on the health effects of a pasteurized sour milk, which is fermented by a starter culture containing lactobacillus helveticus as the predominant microorganism, indicate ... | 2002 | 12369200 |
| genetic diversity in swiss cheese starter cultures assessed by pulsed field gel electrophoresis and arbitrarily primed pcr. | to assess intraspecific genetic heterogeneity among commercial swiss cheese starter culture strains of lactobacillus helveticus, streptococcus thermophilus and propionibacterium freudenreichii and to compare the efficacy of two genetic typing methods. | 2002 | 12390494 |
| modulation of the cell-surface proteinase activity of thermophilic lactobacilli by the peptide supply. | the proteolytic system of thermophilic lactobacilli is considered important for bacterial nutrition as well as for the formation of flavor and texture in fermented products. we investigated the influence of peptide content on the cell surface proteinase and intracellular aminopeptidase activities from seven thermophilic lactobacilli strains. the proteinase activities were remarkably reduced in cells grown in the peptide-rich medium mrs or in a chemically defined medium supplemented with casitone ... | 2002 | 12402076 |
| overexpression of peptidases in lactococcus and evaluation of their release from leaky cells. | walker and klaenhammer (2001) developed a novel expression system in lactococcus lactis that facilitated the release of beta-galactosidase (117 kda monomer) without the need for secretion or export signals. the system is based on the controlled expression of integrated prophage holin and lysin cassettes via a lactococcal bacteriophage phi31 transcriptional activator (tac31a) that resides on a high-copy plasmid. approximately 85% of beta-galactosidase activity was detected in the supernatant of l ... | 2002 | 12416795 |
| production of pyroglutamic acid by thermophilic lactic acid bacteria in hard-cooked mini-cheeses. | pyroglutamic acid is present in high amounts (0.5g/ 100g) in many cheese varieties-and particularly in extensively ripened italian cheeses such as grana padano and parmigiano reggiano. an in vivo model system for cooked mini-cheese production and ripening acceleration was set up to demonstrate the ability of thermophilic lactic acid bacteria, used as a starter, to produce pyroglutamic acid (pglu). in mini-cheeses stored at 38 and 30 degrees c for up to 45 d, all starters tested produced differen ... | 2002 | 12416800 |
| exopolysaccharides produced by lactic acid bacteria of kefir grains. | a lactobacillus delbrueckii subsp. bulgaricus hp1 strain with high exopolysaccharide activity was selected from among 40 strains of lactic acid bacteria, isolated from kefir grains. by associating the lactobacillus delbrueckii subsp. bulgaricus hp1 strain with streptococcus thermophilus t15, lactococcus lactis subsp. lactis c15, lactobacillus helveticus mp12, and sacharomyces cerevisiae a13, a kefir starter was formed. the associated cultivation of the lactobacteria and yeast had a positive effe ... | 2002 | 12440716 |
| early lysis of lactobacillus helveticus cnrz 303 in swiss cheese is not prophage-related. | lactobacillus helveticus is mainly used as starter in swiss-type cheeses. often, lysogenic strains are eliminated because of the risk of early lysis and acidification failure due to phage expression. on the other hand, l. helveticus lysis was shown to positively influence cheese proteolysis during ripening. in order to better assess the relationship between lysis and lysogeny, a prophage-cured derivative of l. helveticus cnrz 303 was isolated (lh 303-g11) and relysogenised (lh 303-g11r), as demo ... | 2003 | 12457589 |
| immunomodulating effects of peptidic fractions issued from milk fermented with lactobacillus helveticus. | the effect of peptides released during the fermentation of milk on the humoral immune system and on fibrosarcoma growth was studied. lactobacillus helveticus was able to release peptidic compounds during milk fermentation due to its high proteolytic activity, as was shown by the degree of proteolysis and size-exclusion hplc elution profiles. three fractions of these compounds were separated and fed to mice during different periods (2, 5, and 7 d). the humoral immune response was assessed by foll ... | 2002 | 12487440 |
| a fermented milk high in bioactive peptides has a blood pressure-lowering effect in hypertensive subjects. | angiotensin-converting enzyme (ace; ec 3.4.15.1) plays a dual role in the regulation of hypertension: it catalyzes the production of the vasoconstrictor angiotensin ii and it inactivates the vasodilator bradykinin. by inhibiting these processes, ace inhibitors have antihypertensive effects. peptides derived from milk proteins can have ace-inhibiting properties and may thus be used as antihypertensive components. | 2003 | 12540390 |