| the secondary substrate binding site of the pseudoalteromonas haloplanktis gh8 xylanase is relevant for activity on insoluble but not soluble substrates. | previously, it has been demonstrated that the glycoside hydrolase family 8 xylanase from the psychrophylic bacterium pseudoalteromonas haloplanktis (xph) can bind substrate non-catalytically on the surface of its catalytic module. in the present study, the functional relevance of this secondary binding site (sbs) for the enzyme is investigated by site-directed mutagenesis and evaluation of activity and binding properties of mutant variants on a range of structurally different homoxylan and heter ... | 2011 | 21656141 |
| diversity of protease-producing marine bacteria from sub-antarctic environments. | from seawater and the intestines of benthonic organisms collected from the beagle channel, argentina, 230 marine bacteria were isolated. cultivable bacteria were characterized and classified as psychrotolerant, whereas few isolates were psychrophiles. these isolates were capable of producing proteases at 4 and 15 °c under neutral (ph 7.0), alkaline (ph 10.0) and acidic (ph 4.5) conditions on different media, revealing 62, 33 and 22% producers at cold and 84, 47 and 33% producers at low temperatu ... | 2011 | 21656810 |
| fusion of the osmc domain from esterase esto confers thermolability to the cold-active xylanase xyn8 from pseudoalteromonas arctica. | the osmc-region (osmotically induced protein family) of the two-domain esterase esto from the psychrotolerant bacterium pseudoalteromonas arctica has been shown to increase thermolability. in an attempt to test if these properties can be conferred to another enzyme, we genetically fused osmc to the 3'-region of the family 8 xylanase encoding gene xyn8 from p. arctica. the chimeric open reading frame xyn8-osmc was cloned and the chimeric protein was purified after heterologous expression in esche ... | 2011 | 21331632 |
| characterization of a gene cluster and its putative promoter region for violacein biosynthesis in pseudoalteromonas sp. 520p1. | violacein, a purple pigment produced by some gram-negative bacteria, has various physiological properties, such as antitrypanosomal and antitumoral activities. a gene cluster that encodes five enzymes, vioa-vioe, is responsible for synthesizing violacein. the expression of these enzymes is known to be regulated by a quorum sensing mechanism in chromobacterium violaceum and pseudoalteromonas sp. 520p1. to clarify the molecular mechanism of regulation of violacein synthesis, we cloned and characte ... | 2011 | 21472536 |
| structural investigation and biological activity of the lipooligosaccharide from the psychrophilic bacterium pseudoalteromonas haloplanktis tab 23. | pseudoalteromonas haloplanktis tab 23 is a gram-negative psychrophilic bacterium isolated from the antarctic coastal sea. to survive in these conditions psychrophilic bacteria have evolved typical membrane lipids and "antifreeze" proteins to protect the inner side of the microorganism. as for gram-negative bacteria, the outer membrane is mainly constituted by lipopoly- or lipooligosaccharides (lps or los, respectively), which lean towards the external environment. despite this, very little is kn ... | 2011 | 21557359 |
| use of psychrophilic xylanases provides insight into the xylanase functionality in bread making. | the bread improving potential of three psychrophilic xylanases from pseudoalteromonas haloplanktis tah3a (xph), flavobacterium sp. msy-2 (rxfh) and unknown bacterial origin (rxyn8) was compared to that of the mesophilic xylanases from bacillus subtilis (xbs) and aspergillus aculeatus (xaa). xph, rxfh and rxyn8 increased specific bread volumes up to 28%, 18% and 18%, respectively, while xbs and xaa gave increases of 23% and 12%, respectively. this could be related to their substrate hydrolysis be ... | 2011 | 21806059 |
| petroleum-influenced beach sediments of the campeche bank, mexico: diversity and bacterial community structure assessment. | the bacterial diversity and community structure were surveyed in intertidal petroleum-influenced sediments of ~100 km of a beach, in the southern gulf of mexico. the beach was divided in twenty sampling sites according to high, moderate and low petroleum influence. densities of cultured heterotrophic (hab) and hydrocarbon degrading bacteria (hdb) were highly variable in sediments, with little morphological assortment in colonies. pcr-risa banding patterns differentiated distinct communities alon ... | 2011 | 21802196 |
| a preliminary study of the microbial resources and their biological activities of the east china sea. | east china sea is one of the four sea areas in china, which possesses peculiar ecological environment and many kinds of living creatures, especially the microorganisms. we established the east china sea microorganism library (during 2006-2010) for the first time, which stored about 30000 strains that covered most kinds of the species. in this paper, 395 pure strains of east china sea microorganism library which belong to 33 different genera were mainly introduced. sulfitobacter, halomonas, bacil ... | 2011 | 21789045 |
| violacein and related tryptophan metabolites produced by chromobacterium violaceum: biosynthetic mechanism and pathway for construction of violacein core. | violacein is a natural violet pigment produced by several gram-negative bacteria, including chromobacterium violaceum, janthinobacterium lividum, and pseudoalteromonas tunicata d2, among others. this pigment has potential medical applications as antibacterial, anti-trypanocidal, anti-ulcerogenic, and anticancer drugs. the structure of violacein consists of three units: a 5-hydroxyindole, an oxindole, and a 2-pyrrolidone. the biosynthetic origins of hydrogen, nitrogen, and carbon in the pyrrolido ... | 2011 | 21779844 |
| performance evaluation on a wide set of matrix-assisted laser desorption ionization matrices for the detection of oligosaccharides in a high-throughput mass spectrometric screening of carbohydrate depolymerizing enzymes. | compared to other analytical methods, matrix-assisted laser desorption ionization mass spectrometry (maldi-ms) presents several unique advantages for the structural characterization of degradation products of carbohydrates. our final goal is to implement this technique as a high-throughput platform, with the aim of exploring natural bio-diversity to discover new carbohydrate depolymerizing enzymes. in this approach, a variety of carbohydrates will be used as enzymes substrates and maldi-ms will ... | 2011 | 21698689 |
| general secretory pathway from marine antarctic pseudoalteromonas haloplanktis tac125. | in gram-negative bacteria type ii secretion system (t2ss) is one of six protein secretion machineries that permit the export of proteins from within the bacterial cell to the extra-cellular milieu and/or into target host cells. the ability to secrete proteins in the extra-cellular medium is a key aspect of the physiology of gram-negative bacteria. indeed, secreted proteins provide the means, among others, by which microorganisms interact and modify the surrounding environment. this is a crucial ... | 2009 | 21798163 |
| discovery of a cytokinin deaminase. | an enzyme of unknown function within the amidohydrolase superfamily was discovered to catalyze the hydrolysis of n-6-substituted adenine derivatives, several of which are cytokinins. cytokinins are a common type of plant hormone and n-6-substituted adenines are also found as modifications to trna. patl2390, from pseudoalteromonas atlantica t6c, was shown to hydrolytically deaminate n-6-isopentenyladenine to hypoxanthine and isopentenylamine with a k(cat)/k(m) of 1.2 +ù 10(7) m(-1) s(-1). additio ... | 2011 | 21823622 |
| cold-adapted bacteria and the globin case study in the antarctic bacterium pseudoalteromonas haloplanktis tac125. | environmental oxygen availability may play an important role in the evolution of polar marine organisms, as suggested by the physiological and biochemical strategies adopted by these organisms to acquire, deliver and scavenge oxygen. stress conditions such as extreme temperatures increase the production of reactive oxygen species (ros) in cells. thus, in order to prevent cellular damage, adjustments in antioxidant defences are needed to maintain the steady-state concentration of ros. cold-adapte ... | 2010 | 21798206 |
| sponge-associated microbial antarctic communities exhibiting antimicrobial activity against burkholderia cepacia complex bacteria. | the aerobic heterotrophic bacterial communities isolated from three different antarctic sponge species were analyzed for their ability to produce antimicrobial compounds active toward cystic fibrosis opportunistic pathogens belonging to the burkholderia cepacia complex (bcc). the phylogenetic analysis performed on the 16s rrna genes affiliated the 140 bacterial strains analyzed to 15 genera. just three of them (psychrobacter, pseudoalteromonas and arthrobacter) were shared by the three sponges. ... | 2011 | 21742025 |
| ligand- and proton-linked conformational changes of the ferrous 2/2 hemoglobin of pseudoalteromonas haloplanktis tac125. | the spectroscopic and ligand-binding properties of a 2/2 globin from the antarctic bacterium pseudoalteromonas haloplanktis tac125 have been studied in the ferrous state. it displays two major conformations characterized by co-association rates that differ by a factor of 20, with relative fractions that depend on ph. a dynamic equilibrium is found between the two conformations, as indicated by an enhanced slower phase when lower co levels were used to allow a longer time to facilitate the transi ... | 2011 | 21698762 |
| influence of a bacteriophage on the population dynamics of toxic dinoflagellates by lysis of algicidal bacteria. | a lytic phage (øzcw1) was isolated from an algicidal bacterium pseudoalteromonas sp. strain sp48 that specifically kills the toxic dinoflagellate alexandrium tamarense. we demonstrated that øzcw1 could trigger the growth of a. tamarense by inhibiting the growth of algicidal bacterium sp48. in contrast, the growth of a. tamarense was suppressed when cocultured with either sp48 or the øzcw1-resistant mutant of sp48. this study provides the first evidence of the indirect impact of bacteriophage on ... | 2011 | 21890676 |
| Regulation of Bacterial Communities Through Antimicrobial Activity by the Coral Holobiont. | Interactions between corals and associated bacteria and amongst these bacterial groups are likely to play a key role in coral health. However, the complexity of these interactions is poorly understood. We investigated the functional role of specific coral-associated bacteria in maintaining microbial communities on the coral Acropora millepora (Ehrenberg 1834) and the ability of coral mucus to support or inhibit bacterial growth. Culture-independent techniques were used to assess bacterial commun ... | 2011 | 21984347 |
| crystal structure of hyperthermophilic endo-β-1,4-glucanase: implications for catalytic mechanism and thermostability. | endo-β-1,4-glucanase from thermophilic fervidobacterium nodosum rt17-b1 (fncel5a), a new member of glycosyl hydrolase family 5, is highly thermostable and exhibits the highest activity on carboxymethylcellulose among the reported homologues. to understand the structural basis for the thermostability and catalytic mechanism, we report here the crystal structures of fncel5a and the complex with glucose at atomic resolution. fncel5a exhibited a (β/α)8-barrel structure typical of clan gh-a of glycos ... | 2011 | 22128157 |
| bacteria immobilised in gels: improved methodologies for antifouling and biocontrol applications. | a range of bacteria, including the marine bacterium pseudoalteromonas tunicata which produces antifouling compounds, and escherichia coli were used to investigate methods for immobilising bacteria in gels. different types of matrices were screened using the survival of barnacle nauplii as a bioassay. a dupont® polyvinylalcohol (pvoh) 10% gel was found to be the optimal matrix. this non-toxic gel remained stable in seawater while allowing for an outflux of active biological compounds from the bac ... | 2000 | 22115296 |
| marine bacterioplankton diversity and community composition in an antarctic coastal environment. | the bacterial community inhabiting the water column at terra nova bay (ross sea, antarctica) was examined by the fluorescent in situ hybridization (fish) technique and the genotypic and phenotypic characterization of 606 bacterial isolates. overall, the fish analysis revealed a bacterioplankton composition that was typical of antarctic marine environments with the cytophaga/flavobacter (cf) group of bacteroidetes that was equally dominant with the actinobacteria and gammaproteobacteria. as sampl ... | 2011 | 21748267 |
| A Novel Strategy for the Construction of Genomic Mutants of the Antarctic Bacterium Pseudoalteromonas haloplanktis TAC125. | The sequencing and the annotation of the marine Antarctic Pseudoalteromonas haloplanktis TAC125 genome has paved the way to investigate on the molecular mechanisms involved in adaptation to cold conditions. The growing interest in this unique bacterium prompted the developing of several genetic tools for studying it at the molecular level. To allow a deeper understanding of the PhTAC125 physiology a genetic system for the reverse genetics in this bacterium was developed. In the present work, we ... | 2012 | 22160901 |
| phylogenetic analysis of culturable marine bacteria in sediments from the south korean yellow sea. | biogeochemical and microbiological characterization of marine sediments taken from the yellow sea of south korea was carried out. one hundred and thirty six bacterial strains were isolated, characterized and phylogenetic relationship was evaluated. the gene sequences of 16s rdna regions were examined to study the phylogenetic analysis of bacterial community in the marine sediments. among 136 isolates, 5 bacterial isolates were identified as novel members, remaining 131 isolates were fall into 5 ... | 2011 | 21675219 |
| purification and characterization of antibacterial compounds of pseudoalteromonas flavipulchra jg1. | pseudoalteromonas flavipulchra jg1 produces a protein pfap and a range of small molecular compounds with inhibitory activities against vibrio anguillarum. the pfap protein was purified from the extracellular products of jg1 by electroelution, and antibacterial activity was observed by the in-gel antibacterial assay. the complete amino acid sequence (694 aa) of pfap was determined by de novo peptide sequencing and subsequently aligning with the proteome sequence of strain jg1. the calculated mole ... | 2011 | 22194352 |
| the anti-biofilm activity secreted by a marine pseudoalteromonas strain. | bacterial biofilms occur on all submerged structures in marine environments. the authors previously reported that the marine bacterium pseudoalteromonas sp. 3j6 secretes antibiofilm activity. here, it was discovered that another pseudoalteromonas sp. strain, d41, inhibited the development of strain 3j6 in mixed biofilms. confocal laser scanning microscope observations revealed that the culture supernatant of strain d41 impaired biofilm formation of strain 3j6 and another marine bacterium. a micr ... | 2011 | 21895460 |
| diversity and antimicrobial activities of microbes from two irish marine sponges, suberites carnosus and leucosolenia sp. | aims: to evaluate the diversity and antimicrobial activity of bacteria from the marine sponges suberites carnosus and leucosolenia sp. methods and results: two hundred and thirty-seven bacteria were isolated from the sponges s. carnosus (demospongiae) and leucosolenia sp. (calcarea). isolates from the phyla actinobacteria, bacteroidetes, firmicutes and proteobacteria were obtained. isolates of the genus pseudovibrio were dominant among the bacteria from s. carnosus, whereas pseudoalteromonas a ... | 2011 | 22129274 |
| isolation and characterization of a novel agarase-producing pseudoalteromonas spp. bacterium from the guts of spiny turban shells. | an agar-degrading bacterium was isolated from the guts of spiny turban shells. it was identified as a pseudoalteromonas species and named pseudoalteromonas sp. jybcl 1. the viscosity of the inoculated agar medium decreased by more than 60% after 20 h cultivation. the agarase produced by the isolate had optimal activities at 35 degrees c and ph 7. the enzyme had extremely strong resistance to ionic stress compared with other known agarases. its molecular mass was estimated at about 60 kda by sodi ... | 2011 | 21876371 |
| structure and activity of exo-1,3/1,4-β-glucanase from marine bacterium pseudoalteromonas sp. bb1 showing a novel c-terminal domain. | following the discovery of an exo-1,3/1,4-β-glucanase (glycoside hydrolase family 3) from a seaweed-associated bacterium pseudoalteromonas sp. bb1, the recombinant three-domain protein (exop) was crystallized and its structure solved to 2.3 å resolution. the first two domains of exop, both of which contribute to the architecture of the active site, are similar to those of the two-domain barley homologue β-d-glucan exohydrolase (exoi) with a distinctive trp-trp clamp at the +1 subsite, although e ... | 2011 | 22129429 |
| suitability of different β-galactosidases as reporter enzymes in bacillus subtilis. | the suitability of three β-galactosidases as reporter enzymes for promoter expression analyses was investigated in bacillus subtilis with respect to various temperature conditions during cultivation and assay procedures. starting from the hypothesis that proteins derived from diverse habitats have different advantages as reporters at different growth temperatures, the beta-galactosidases from the thermophilic organism bacillus stearothermophilus, from the mesophilic bacterium escherichia coli an ... | 2011 | 22052389 |
| Improving Protein Crystal Quality by the Without-Oil Microbatch Method: Crystallization and Preliminary X-ray Diffraction Analysis of Glutathione Synthetase from Pseudoalteromonas haloplanktis. | Glutathione synthetases catalyze the ATP-dependent synthesis of glutathione from l-?-glutamyl- l-cysteine and glycine. Although these enzymes have been sequenced and characterized from a variety of biological sources, their exact catalytic mechanism is not fully understood and nothing is known about their adaptation at extremophilic environments. Glutathione synthetase from the Antarctic eubacterium Pseudoalteromonas haloplanktis (PhGshB) has been expressed, purified and successfully crystallize ... | 2011 | 22016660 |
| characterisation of the microbiota of atlantic mackerel (scomber scombrus). | in this study the microbiota of atlantic mackerel (scomber scombrus) collected by a commercial purse seiner was examined. fish were collected directly from the purse seine and from the refrigerated sea water (rsw) transport tank after loading. the culturable microbiota and specific spoilage bacteria (ssb) were quantified on iron agar lyngby (ial) and identified using commercially available biochemical api® kits on pure cultured isolates. these kits showed to be sub-optimal in characterising the ... | 2011 | 21914558 |
| the structural diversity of carbohydrate antigens of selected gram-negative marine bacteria. | marine microorganisms have evolved for millions of years to survive in the environments characterized by one or more extreme physical or chemical parameters, e.g., high pressure, low temperature or high salinity. marine bacteria have the ability to produce a range of biologically active molecules, such as antibiotics, toxins and antitoxins, antitumor and antimicrobial agents, and as a result, they have been a topic of research interest for many years. among these biologically active molecules, t ... | 2011 | 22073003 |
| marine bacteria from danish coastal waters show antifouling activity against the marine fouling bacterium pseudoalteromonas sp. strain s91 and zoospores of the green alga ulva australis independent of bacteriocidal activity. | the aims of this study were to determine if marine bacteria from danish coastal waters produce antifouling compounds and if antifouling bacteria could be ascribed to specific niches or seasons. we further assess if antibacterial effect is a good proxy for antifouling activity. we isolated 110 bacteria with anti-vibrio activity from different sample types and locations during a 1-year sampling from danish coastal waters. the strains were identified as pseudoalteromonas, phaeobacter, and vibrionac ... | 2011 | 22003011 |
| Stepwise adaptations to low temperature as revealed by multiple mutants of psychrophilic a-amylase from Antarctic Bacterium. | The mutants Mut5 and Mut5CC from a psychrophilic a-amylase bear representative stabilizing interactions found in the heat-stable porcine pancreatic a-amylase but lacking in the cold-active enzyme from an Antarctic bacterium. From an evolutionary perspective, these mutants can be regarded as structural intermediates between the psychrophilic and the mesophilic enzymes. We found that these engineered interactions improve all the investigated parameters related to protein stability as follows: comp ... | 2011 | 21900238 |
| coastal seawater bacteria harbor a large reservoir of plasmid-mediated quinolone resistance determinants in jiaozhou bay, china. | diversity and prevalence of plasmid-mediated quinolone resistance determinants were investigated in environmental bacteria isolated from surface seawater of jiaozhou bay, china. five qnr gene alleles were identified in 34 isolates by pcr amplification, including qnra3 gene in a shewanella algae isolate, qnrb9 gene in a citrobacter freundii isolate, qnrd gene in 22 proteus vulgaris isolates, qnrs1 gene in 1 enterobacter sp. and 4 klebsiella spp. isolates, and qnrs2 gene in 1 pseudomonas sp. and 4 ... | 2012 | 22252223 |
| structural prediction and comparative docking studies of psychrophilic ß- galactosidase with lactose, onpg and pnpg against its counter parts of mesophilic and thermophilic enzymes. | enzymes from psychrophiles catalyze the reactions at low temperatures with higher specific activity. among all the psychrophilic enzymes produced, cold active ß-galactosidase from marine psychrophiles revalorizes a new arena in numerous areas at industrial level. the hydrolysis of lactose in to glucose and galactose by cold active ß-galactosidase offers a new promising approach in removal of lactose from milk to overcome the problem of lactose intolerance. herein we propose, a 3d structure of co ... | 2011 | 21769193 |
| Regulated Recombinant Protein Production in the Antarctic Bacterium Pseudoalteromonas haloplanktis TAC125. | This review reports results from our laboratory on the development of an effective inducible expression system for the homologous/heterologous protein production in cold-adapted bacteria. Recently, we isolated and characterized a regulative genomic region from Pseudoalteromonas haloplanktis TAC125; in particular, a two-component regulatory system was identified. It is involved in the transcriptional regulation of the gene coding for an outer membrane porin (PSHAb0363) that is strongly induced by ... | 2012 | 22160900 |
| characterization of the volatile profile of antarctic bacteria by using solid-phase microextraction-gas chromatography-mass spectrometry. | bacteria belonging to the burkholderia cepacia complex (bcc) are significant pathogens in cystic fibrosis (cf) patients and are resistant to a plethora of antibiotics. in this context, microorganisms from antarctica are interesting because they produce antimicrobial compounds inhibiting the growth of other bacteria. this is particularly true for bacteria isolated from antarctic sponges. the aim of this work was to characterize a set of antarctic bacteria for their ability to produce new natural ... | 2011 | 22012672 |