| cloning and characterization of the siga gene encoding the major sigma subunit of rhizobium meliloti. | using pcr to create a probe based on conserved region 2 of sigma factors, we have cloned the siga gene coding for the major sigma factor of rhizobium meliloti. the 684-residue protein encoded by the siga gene was expressed in vitro in coupled transcription-translation experiments with r. meliloti extracts and migrated aberrantly in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. its deduced amino acid sequence is similar to that of rpod of escherichia coli and is nearly identical to t ... | 1995 | 7592490 |
| fragmentations of the large-subunit rrna in the family rhizobiaceae. | a 130-nucleotide-long rrna species corresponding to the 5' end of the 23s rrna gene was found in 96 strains belonging to different rhizobium, bradyrhizobium, and agrobacterium species. additional fragmentation in the central region of the large-subunit rrna occurred in all agrobacteria, except agrobacterium vitis, and in most rhizobium leguminosarum and rhizobium etli strains but did not occur in any of the other rhizobia and bradyrhizobia studied. | 1995 | 7592497 |
| genetic analysis of nonpathogenic agrobacterium tumefaciens mutants arising in crown gall tumors. | little is known about the effect of the host on the genetic stability of bacterial plant pathogens. crown gall, a plant disease caused by agrobacterium tumefaciens, may represent a useful model to study this effect. indeed, our previous observations on the natural occurrence and origin of nonpathogenic agrobacteria suggest that the host plant might induce loss of pathogenicity in populations of a. tumefaciens. here we report that five different a. tumefaciens strains initially isolated from appl ... | 1995 | 7601840 |
| supraoperonic clustering of pca genes for catabolism of the phenolic compound protocatechuate in agrobacterium tumefaciens. | the protocatechuate branch of the beta-ketoadipate pathway comprises the last six enzymatic steps in the catabolism of diverse phenolic compounds to citric acid cycle intermediates. in this paper, the regulation and tight supraoperonic clustering of the protocatechuate (pca) genes from agrobacterium tumefaciens a348 are elucidated. a previous study found that the pcad gene is controlled by an adjacent regulatory gene, pcaq, which encodes an activator. the activator responded to beta-carboxy-cis, ... | 1995 | 7601847 |
| [cloning and heterologous expression of the escherichia coli probosm proa operon in the bacterial symbiont of soy, rhizobium fredii]. | effects of recombinant bacteria rhizobium fredii/pnsa, content of probosm proa operon, and r.fredii/plva, content of proba wild type operon, on soybean plants were studied. r.fredii bd32/pnsa were found to synthesize more proline and to express higher osmotolerance than r.fredii bd32/plva or wild type bacteria. plants infected with r.fredii bd32/pnsa were characterized by lower water consumption before blooming. moreover, these bacteria were found to promote more rapid sprout of seeds under unfa ... | 1995 | 7603487 |
| effect of the m-ecorii methyltransferase-encoding gene on the phenotype of nicotiana tabacum transgenic cells. | the ecorii dna methyltransferase (m-ecorii; mtase) modifies a cytosine in the dna sequence ccwgg which contains a cng methylation motif characteristic of plant dna. the gene (ecoriim) encoding this mtase has been cloned into the t-dna of the wild-type agrobacterium ti-plasmid ptic58 downstream from the plant expression nopaline synthase-encoding gene promoter. nicotiana tabacum cells have been transformed with agrobacterium tumefaciens harbouring this recombinant ti-plasmid. the primary transfor ... | 1995 | 7607509 |
| [transcriptional control of the agrobacterium virulence genes]. | | 1995 | 7610258 |
| phylogenetic relationships and host range of rhizobium spp. that nodulate phaseolus vulgaris l. | we determined the nucleotide sequences of 16s rrna gene segments from five rhizobium strains that have been isolated from tropical legume species. all share the capacity to nodulate phaseolus vulgaris l., the common bean. phylogenetic analysis confirmed that these strains are of two different chromosomal lineages. we defined the host ranges of two strains of rhizobium etli and three strains of r. tropici, comparing them with those of the two most divergently related new strains. twenty-two of th ... | 1995 | 7618891 |
| effect of some environmental factors on rhizobium and bradyrhizobium strains. | effects of different abiotic factors (acidity, salinity, nitrate and temperature) on growth rate of root-nodule bacteria (rhizobium and bradyrhizobium) strains were investigated in vitro. strains isolated from vicia faba l., coronilla varia l. and lupinus albus l. exhibited a large variation in tolerance of the above-mentioned factors. these bacteria should be screened under stimulated conditions for enhanced survival before selection to be used for commercial inoculant production. linear correl ... | 1995 | 7620814 |
| trans-kingdom t-dna transfer from agrobacterium tumefaciens to saccharomyces cerevisiae. | agrobacterium tumefaciens transfers part of its tumour-inducing (ti) plasmid, the transferred or t-dna, to plants during tumourigenesis. this represents the only example of naturally occurring trans-kingdom transfer of genetic material. here we report that a.tumefaciens can transfer its t-dna not only to plant cells, but also to another eukaryote, namely the yeast saccharomyces cerevisiae. the ti plasmid virulence (vir) genes that mediate t-dna transfer to plants were found to be essential for t ... | 1995 | 7621833 |
| the hrp gene locus of pseudomonas solanacearum, which controls the production of a type iii secretion system, encodes eight proteins related to components of the bacterial flagellar biogenesis complex. | five transcription units of the pseudomonas solanacearum hrp gene cluster are required for the secretion of the hr-inducing popa1 protein. the nucleotide sequences of two of these, units 1 and 3, have been reported. here, we present the nucleotide sequence of the three other transcription units, units 2, 4 and 7, which are together predicted to code for 15 hrp genes. this brings the total number of hrp proteins encoded by these five transcription units to 20, including hrpb, the positive regulat ... | 1995 | 7623665 |
| analysis of a chemotaxis operon in rhizobium meliloti. | genes controlling chemotaxis towards l-amino acids and d-mannitol in rhizobium meliloti have been identified by tn5 insertions that lead to chemotaxis-deficient mutants. the tagged genes span an 8.7 kbp region that has been sequenced. these genes are part of a large operon containing three novel open reading frames, orf1, orf2 and orf9, and six familiar chemotaxis (che) genes, chey1-chea-chew-cher-cheb-chey2, that have been assigned by their similarity to known escherichia coli genes. the second ... | 1995 | 7623670 |
| the agrobacterium tumefaciens virulence d2 protein is responsible for precise integration of t-dna into the plant genome. | the vird2 protein of agrobacterium tumefaciens was shown to pilot t-dna during its transfer to the plant cell nucleus. we analyze here its participation in the integration of t-dna by using a vird2 mutant. this mutation reduces the efficiency of t-dna transfer, but the efficiency of integration of t-dna per se is unaffected. southern and sequence analyses of integration events obtained with the mutated vird2 protein revealed an aberrant pattern of integration. these results indicate that the wil ... | 1995 | 7628458 |
| rhizobium tropici nodulation factor sulfation is limited by the quantity of activated form of sulfate. | rhizobium tropici is a broad host-range symbiont of phaseolus vulgaris. this bacterium produces a mixture of sulfated and non-sulfated n-methylated pentameric nodulation (nod) factors. to understand the genetic bases of the partial sulfation of r. tropici nod factors, which might be involved in the broad host-range of this species, we introduced in r. tropici cfn299 the recombinant plasmid pgmi515 carrying a set of nodulation (nod) genes of r. meliloti, including those involved in the sulfation ... | 1995 | 7635216 |
| suppression of the fix- phenotype of rhizobium meliloti exob mutants by lpsz is correlated to a modified expression of the k polysaccharide. | the rhizobial production of extracellular polysaccharide (eps) is generally required for the symbiotic infection of host plants that form nodules with an apical meristem (indeterminate nodules). one exception is rhizobium meliloti ak631, an exob mutant of rm41, which is deficient in eps production yet infects and fixes nitrogen (i.e., is fix+) on alfalfa, an indeterminate nodule-forming plant. a mutation of lpsz in ak631 results in a fix- strain with altered phage sensitivity, suggesting that a ... | 1995 | 7635814 |
| lipid a biosynthesis in rhizobium leguminosarum: role of a 2-keto-3-deoxyoctulosonate-activated 4' phosphatase. | lipid a from several strains of the n2-fixing bacterium rhizobium leguminosarum displays significant structural differences from escherichia coli lipid a, one of which is the complete absence of phosphate groups. however, the first seven enzymes of e. coli lipid a biosynthesis, leading from udp-glcnac to the phosphorylated intermediate, 2-keto-3-deoxyoctulosonate (kdo2)-lipid iva, are present in r. leguminosarum. we now describe a membrane-bound phosphatase in r. leguminosarum extracts that remo ... | 1995 | 7638195 |
| regulation of gene expression in bacterial pathogens. | | 1994 | 7639782 |
| lipo-oligosaccharide signalling: the mediation of recognition and nodule organogenesis induction in the legume-rhizobium symbiosis. | | 1994 | 7639792 |
| bacterial and plant glycoconjugates at the rhizobium-legume interface. | many classes of bacterial and plant glycoconjugate have been shown to be involved in establishing the rhizobium root nodule symbiosis with peas (pisum sativum). it was demonstrated, using techniques of molecular genetics, that a group of rhizobium nodulation genes (nod genes) co-operate to synthesize a lipo-oligosaccharide signal molecule that specifically initiates nodule development on legume hosts. an additional gene function, encoded by nodx, has been found to extend the host range of rhizob ... | 1994 | 7639793 |
| rhizobium leguminosarum nodt is related to a family of outer-membrane transport proteins that includes tolc, prtf, cyae and aprf. | cells containing a protein fusion consisting of the rhizobium leguminosarum bv. viciae nodulation protein, nodt, fused to phoa, produced alkaline phosphatase activity, indicating that the n terminus of nodt could translocate phoa across the inner membrane. cellular fractionation suggested that the nodt::phoa fusion is targetted to the outer membrane. nodt resembles a family of bacterial outer membrane proteins including tolc, prtf, cyae and aprf, which are involved in secretion. by analogy, nodt ... | 1995 | 7642132 |
| identification and activity of two insertion sequence elements in rhodococcus sp. strain igts8. | two putative insertion sequence (is) elements, is1166 and is1295, were identified on a plasmid present in rhodococcus sp. igts8. four copies of is1166 were present in strain igts8: one copy on each of two separate plasmids and two copies on a third plasmid or in the chromosome. of eight rhodococci tested, only r. zopfii contained a copy of an is1166-like element. two mutants of strain igts8 were isolated in which an additional copy of is1166 was present, suggesting that at least one copy of this ... | 1995 | 7642133 |
| sequences of nifx, nifw, nifz, nifb and two orf in the frankia nitrogen fixation gene cluster. | the actinomycete frankia alni fixes n2 in root nodules of several non-leguminous plants. it is one of the few known n2-fixing members of the high-gc gram+ lineage of prokaryotes. thus, we have undertaken a study of its nitrogen fixation gene (nif) organization to compare with that of the more extensively characterized proteobacteria. a cosmid (pfn1) containing the nif region of fa cpi1 was isolated from a cosmid library using the nifhdk genes of fa cpi1 as a probe. a 4.5-kb bamhi fragment that m ... | 1995 | 7642138 |
| nicotiana benthamiana plants transformed with the 54-kda region of the pepper mild mottle tobamovirus replicase gene exhibit two types of resistance responses against viral infection. | nicotiana benthamiana plants transformed with the 54-kda region of the pepper mild mottle tobamovirus (pmmv) replicase gene were generated and six independently transformed plant lines were analyzed for resistance to pmmv. two different resistance responses were obtained. some of the transgenic plants from only two lines showed a preestablished, complete, and highly resistant phenotype since no viral symptoms were observed, although a low level of virus replication occurred. the remaining plants ... | 1995 | 7645209 |
| identification of rhizobium spp. in peat-based inoculants by dna hybridization and pcr and its application in inoculant quality control. | procedures based on dna hybridization and pcr were developed for quality control of rhizobium inoculants. inoculants for pea and goat's rue were produced by elomestari ltd., juva, finland, in sterile dry fine peat by the standard procedure used by the company. the inoculants contained rhizobium galegae hambi 1174 and hambi 1207 and an r. leguminosarum biovar vicia strain, 16hsa, either solely or in combinations of two or three strains. dna was isolated from 1-g samples of each peat inoculant and ... | 1995 | 7646020 |
| biotoxic effects of copper on ureide metabolism of pigeon pea. | | 1995 | 7647505 |
| a rhizobium meliloti ferredoxin (fdxn) purified from escherichia coli donates electrons to rhodobacter capsulatus nitrogenase. | the fdxn gene from rhizobium meliloti encoding a bacterial-type ferredoxin (fdxn) was expressed in escherichia coli under the control of the lac promoter. the fdxn gene product was purified under anaerobic conditions by ion-exchange chromatography and gel-filtration steps using an antiserum raised against an fdxn-lacz fusion protein as a detection system. the purified ferredoxin was shown to be identical to the predicted r. meliloti fdxn protein in its amino acid composition and n-terminal amino ... | 1995 | 7649175 |
| expression of the plum pox coat protein gene in transgenic nicotiana tabacum plants. | plant expression vector pbi 121 containing the gene encoding coat protein of plum pox virus of the skierniewice isolate (cp ppv-s) was prepared (clone pcm1). the construct was used for transformation of nicotiana tabacum plants using an agrobacterium tumefaciens based system. about 82% of kanamycin resistant plant lines contained a transgene (the sequence of cp ppv-s) but only 81% of them actively expressed the ppv-s coat protein gene as measured by rt-pcr. | 1995 | 7653168 |
| identification and characterization of a rhizobium leguminosarum bv. phaseoli gene that is important for nodulation competitiveness and shows structural homology to a rhizobium fredii host-inducible gene. | dna sequence analysis of a 1.4-kb sali-hindiii segment located approximately 2 kb upstream of the rhizobium leguminosarum bv. phaseoli syrm gene revealed the presence of an open reading frame (orf3) encoding a putative 295-amino acid polypeptide with a molecular mass of 33,401 da. orf3 is homologous to a r. fredii host-inducible gene. the proteins encoded by r. l. bv. phaseoli orf3 and by the r. fredii host-inducible gene share 37% sequence identity. in contrast to the r. fredii host-inducible g ... | 1995 | 7655066 |
| early nodulin gene expression during nod factor-induced processes in vicia sativa. | rhizobium leguminosarum bv. viciae-secreted nod factors are able to induce root hair deformation, the formation of nodule primordia and the expression of early nodulin genes in vicia sativa (vetch). to obtain more insight into the mode of action of nod factors the expression of early nodulin genes was followed during nod factor-induced root hair deformation and nodule primordium formation. the results of these studies suggested that the expression of vsenod5 and vsenod12 is not required for root ... | 1995 | 7655502 |
| pbinplus: an improved plant transformation vector based on pbin19. | we describe the construction of a new plant transformation vector, pbinplus, based on the popular pbin19 vector. improvements over pbin19 include location of the selectable marker gene at the left t-dna border, a higher copy number in e. coli, and two rare restriction sites around the multiple cloning site for easier cloning and analysis of t-dna insertions in plant genomes. | 1995 | 7655517 |
| effect of nitrogen fixation, nitrogen fertilization and viral infection on yield, tannin and protein contents and in vitro protein digestibility of faba bean. | a field investigation of two faba bean cultivars (cv.), agabat and silaim, showed that bean yellow mosaic virus (bymv) infection reduced (p < or = 0.001) yield (kg/ha), protein content and in vitro protein digestibility (ivpd) but increased (p < or = 0.05) tannin content (mg/100 ml). nitrogen fertilization with viral infection significantly reduced yield and ivpd for cv. silaim and increased (p < or = 0.05) protein and tannin contents. nitrogen fertilization alone was found to increase (p < or = ... | 1995 | 7659703 |
| accumulation of arsenic and zinc in the rhizosphere of wetland plants. | | 1995 | 7663086 |
| interactions of virb9, -10, and -11 with the membrane fraction of agrobacterium tumefaciens: solubility studies provide evidence for tight associations. | the eleven predicted gene products of the agrobacterium tumefaciens virb operon are believed to form a transmembrane pore complex through which t-dna export occurs. the virb10 protein is required for virulence and is a component of an aggregate associated with the membrane fraction of a. tumefaciens. removal of the putative membrane-spanning domain (amino acids 22 through 55) disrupts the membrane topology of virb10 (j. e. ward, e. m. dale, e. w. nester, and a. n. binns, j. bacteriol. 172:5200-5 ... | 1995 | 7665464 |
| inhibition of virb-mediated transfer of diverse substrates from agrobacterium tumefaciens by the incq plasmid rsf1010. | the transfer of dna from agrobacterium tumefaciens into a plant cell requires the activities of several virulence (vir) genes that reside on the tumor-inducing (ti) plasmid. the putative transferred intermediate is a single-stranded dna (t strand), covalently attached to the vird2 protein and coated with the single-stranded dna-binding protein, vire2. the movement of this intermediate out of agrobacterium cells and into plant cells requires the expression of the virb operon, which encodes 11 pro ... | 1995 | 7665465 |
| characterization of the cychjkl genes involved in cytochrome c biogenesis and symbiotic nitrogen fixation in rhizobium leguminosarum. | mutants of rhizobium leguminosarum bv. viciae unable to respire via the cytochrome aa3 pathway were identified by the inability to oxidize n,n'-dimethyl-p-phenylenediamine. two mutants which were complemented by cosmid pij1942 from an r. leguminosarum clone bank were identified. although pea nodules induced by these mutants contained many bacteroids, no symbiotic nitrogen fixation was detected. heme staining of cellular proteins revealed that all cytochrome c-type heme proteins were absent. thes ... | 1995 | 7665469 |
| a single rrna gene region in bradyrhizobium japonicum. | bradyrhizobium japonicum contains only a single rrna (rrn) gene region, despite its comparatively large genome size of 8,700 kb. the nucleotide sequence revealed an organization of rrna and trna genes that is frequently found in bacteria: 5'-rrs (16s rrna)-ilet (trna(ile))-alat (trna(ala))-rrl (23s rrna)-rrf (5s rrna)-3'. the 5' end of the primary transcript, one of the 16s rrna processing sites, and the 5' end of the mature 16s rrna were determined by primer extension. dna hybridization experim ... | 1995 | 7665496 |
| growth phase-dependent induction of stationary-phase promoters of escherichia coli in different gram-negative bacteria. | rsf1010-derived plasmids carrying a fusion of a promoterless lacz gene with the sigma s-dependent growth phase-regulated promoters of escherichia coli, bolap1 and fic, were constructed. the plasmids were mobilized into the gram-negative bacterial species acetobacter methanolicus, xanthomonas campestris, pseudomonas putida, and rhizobium meliloti. the beta-galactosidase activities of bacterial cultures were determined during exponential and stationary growth phases. transcriptional activation of ... | 1995 | 7665531 |
| construction of chimeric beta-glucosidases with improved enzymatic properties. | the amino acid sequences of beta-glucosidases from cellvibrio gilvus and agrobacterium tumefaciens show about 40% similarity. the ph/temperature optima and stabilities and substrate specificities of the two enzymes are quite different. c. gilvus beta-glucosidase exhibits an optimum ph of 6.2-6.4 and temperature of 35 degrees c, whereas the corresponding values for a. tumefaciens are 7.2-7.4 and 60 degrees c, respectively. the substrate specificity of a. tumefaciens enzyme toward different aryl g ... | 1995 | 7665615 |
| mutation or increased copy number of node has no effect on the spectrum of chitolipooligosaccharide nod factors made by rhizobium leguminosarum bv. trifolii. | the bacterial gene node is the key determinant of host specificity in the rhizobium leguminosarum-legume symbiosis and has been proposed to determined unique polyunsaturated fatty acyl moieties in chitolipooligosaccharides (clos) made by the bacterial symbiont. we evaluated node function by examining clos structures made by wild-type r. leguminosarum bv. trifolii anu843, an isogenic node::tn5 mutant, and a recombinant strain containing multiple copies of the psym nod region of anu843. 1h-nmr, el ... | 1995 | 7673121 |
| transgene copy number can be positively or negatively associated with transgene expression. | two different types of t-dna insert were found in tobacco plants transformed with agrobacterium tumefaciens. high-expressing (h) types had one copy of the t-dna at a locus and produced high expression of the transgene uida, as measured by uida rna levels and beta-glucuronidase activity; low-expressing (l) types had inverted repeats of the t-dna at a locus and produced low uida expression. h-types from different transformants acted additively, and cross-fertilization between two different homozyg ... | 1993 | 7678759 |
| identification of two alfalfa early nodulin genes with homology to members of the pea enod12 gene family. | in a search for plant genes expressed during early symbiotic interactions between medicago sativa and rhizobium meliloti, we have isolated and characterized two alfalfa genes which have strong sequence similarity to members of the enod12 gene family of pisum sativum. the m. sativa genes, msenod12a and b, encode putative protein products of 8066 da and 12849 da, respectively, each with a signal sequence at the n-terminus followed by a repetitive proline-rich region. based on their expression duri ... | 1993 | 7678770 |
| treatment of agrobacterium or leaf disks with 5-azacytidine increases transgene expression in tobacco. | we have studied the effect of the demethylating agent azacytidine (azac) on expression of a beta-glucuronidase (gus) gene transferred to tobacco leaf disks by agrobacterium-mediated transformation. in a system where no selection was performed, where shoot formation was partially repressed, and where agrobacterium does not express the gus gene, we were able to follow the early events of transient and stable expression. two days after inoculation, 8% of the cells expressed gus but this proportion ... | 1993 | 7680239 |
| phylogenetic analysis of the family rhizobiaceae and related bacteria by sequencing of 16s rrna gene using pcr and dna sequencer. | the 16s rrna gene sequences of 19 strains covering 97% of the molecules were determined for the members of the family rhizobiaceae and related bacteria by pcr and dna sequencer. the three biovars of agrobacterium were located separately, whereas agrobacterium rubi clustered with a. tumefaciens. phylogenetic locations for the species of the genera rhizobium, sinorhizobium, agrobacterium, phylobacterium, mycoplana (m. dimorpha), ochrobactrum, brucella and rochalimaea (a rickettsia) were intermingl ... | 1993 | 7682191 |
| diversity of retron elements in a population of rhizobia and other gram-negative bacteria. | genetic elements called retrons reside on the chromosome of escherichia coli and the myxobacteria and represent the first reverse transcriptase-encoding element to be found in a prokaryotic cell. all known retrons produce a functionally obscure rna-dna satellite molecule called multicopy single-stranded dna (msdna). we report here the presence of msdna-producing retron elements in a number of new bacterial groups, including strains of the genera proteus, klebsiella, salmonella, nannocystis, rhiz ... | 1993 | 7686549 |
| cloning and characterization of an ftsz homologue from a bacterial symbiont of drosophila melanogaster. | a 1194 bp open reading frame that codes for a 398 amino acid peptide was cloned from a lambda gt11 library of drosophila melanogaster genomic dna. the predicted peptide sequence is very similar to three previously characterized protein sequences that are encoded by the ftsz genes in escherichia coli, bacillus subtilis and rhizobium meliloti. the ftsz protein has a major role in the initiation of cell division in prokaryotic cells. using a tetracycline treatment that eradicates bacterial parasite ... | 1993 | 7689140 |
| the bacterial attachment site of the temperate rhizobium phage 16-3 overlaps the 3' end of a putative proline trna gene. | bacteriophage 16-3 inserts its genome into the chromosome of rhizobium meliloti strain 41 (rm41) by site-specific recombination. the dna regions around the bacterial attachment site (attb) and one of the hybrid attachment sites bordering the integrated prophage (attl) were cloned and their nucleotide sequences determined. we demonstrated that the 51 bp region, where the phage and bacterial dna sequences are identical, is active as a target site for phage integration. furthermore it overlaps the ... | 1993 | 7689141 |
| preparation, optimization and characterization of a polyphenylalanine synthetizing system from agrobacterium tumefaciens. | a very active cell-free translation system was prepared from agrobacterium tumefaciens, a bacterium broadly used to transfect plant cells to introduce foreign genes and one that produces tumours in plants. once optimized for mg2+, nh4+, high speed supernatant s 370, purified ribosomes and time, the system translates polyuridylic acid very efficiently. a. tumefaciens purified ribosomes were inhibited in vitro by several well-known translational inhibitors including some ribosome-inactivating prot ... | 1993 | 7693097 |
| inhibition of viroid infection by antisense rna expression in transgenic plants. | complex formation between different antisense rnas directed against either plus-strand or minus-strand sequences of the potato spindle tuber viroid (pstvd) was studied using temperature-gradient gel electrophoresis and immunochemical detection with an antibody specific for double-stranded rna. short minus-strand sequences were directed against the upper central conserved region (uccr) of plus-strand viroid replication intermediates, a plus-strand corresponding to the left half of the rod-like se ... | 1994 | 7695839 |
| transient induction of a peroxidase gene in medicago truncatula precedes infection by rhizobium meliloti. | although key determinative events of the rhizobium-legume symbiosis are likely to precede bacterial infection, no plant genes have been identified that are expressed strongly prior to infection and nodule morphogenesis. a subtractive hybridization-polymerase chain reaction technique was used to enrich for genes induced during the early phases of the r. meliloti-medicago truncatula symbiosis. one gene so identified encodes a putative plant peroxidase protein, which we have named rip1 for rhizobiu ... | 1995 | 7696879 |
| sucrose analogues modified at position 3: chemoenzymatic synthesis and inhibition studies of dextransucrases. | conditions for the large-scale (molar) oxidation of sucrose by agrobacterium tumefaciens were improved, thus leading to homogeneous solutions of 3-ketosucrose in 40% yield. treatment of this solution with hydroxylamine or methoxylamine afforded the corresponding oximes 3a and 3b (isolated as acetates) in excellent yield. dissolving-metal reduction of these oximes gave mixtures of amino disaccharides in which the gluco epimer (3-amino-3-deoxysucrose) was predominant. a more efficient approach to ... | 1995 | 7697661 |
| a chromosomal cluster of genes encoding adp-glucose synthetase, glycogen synthase and phosphoglucomutase in agrobacterium tumefaciens. | | 1995 | 7698662 |
| common links in the structure and cellular localization of rhizobium chitolipooligosaccharides and general rhizobium membrane phospholipid and glycolipid components. | several common links between the structural chemistry of the chitolipooligosaccharides of rhizobium and the general rhizobial membrane lipid and lipopolysaccharide chemistry of these bacteria have been uncovered. aspects of common chemistry include sulfation, methylation, and the position and extent of fatty acyl chain unsaturation. we find that bacteria which are known to synthesize sulfated chitolipooligosaccharides (such as rhizobium meliloti strains and the broad-host-range rhizobium species ... | 1995 | 7703260 |
| chloroplast gene sequence data suggest a single origin of the predisposition for symbiotic nitrogen fixation in angiosperms. | of the approximately 380 families of angiosperms, representatives of only 10 are known to form symbiotic associations with nitrogen-fixing bacteria in root nodules. the morphologically based classification schemes proposed by taxonomists suggest that many of these 10 families of plants are only distantly related, engendering the hypothesis that the capacity to fix nitrogen evolved independently several, if not many, times. this has in turn influenced attitudes toward the likelihood of transferri ... | 1995 | 7708699 |
| characterization of a binding site for chemically synthesized lipo-oligosaccharidic nodrm factors in particulate fractions prepared from roots. | this paper describes the characteristics of a binding site for the major, lipo-oligosaccharide nod factor of rhizobium meliloti in roots of the symbiotic host plant, medicago truncatula. chemically synthesized nodrm-iv(ac, s, c16:2) was labelled by tritiation to a specific activity of 56 ci mmol-1 and this ligand was shown to be biologically active in the root hair deformation assay at 10(-11) m. binding of the ligand to a particulate fraction from roots of m. truncatula was found to be saturabl ... | 1995 | 7704048 |
| the rhizobium-plant symbiosis. | rhizobium, bradyrhizobium, and azorhizobium species are able to elicit the formation of unique structures, called nodules, on the roots or stems of the leguminous host. in these nodules, the rhizobia convert atmospheric n2 into ammonia for the plant. to establish this symbiosis, signals are produced early in the interaction between plant and rhizobia and they elicit discrete responses by the two symbiotic partners. first, transcription of the bacterial nodulation (nod) genes is under control of ... | 1995 | 7708010 |
| in vitro sulfotransferase activity of rhizobium meliloti nodh protein: lipochitooligosaccharide nodulation signals are sulfated after synthesis of the core structure. | the rhizobium common nod gene products nodabc are involved in the synthesis of the core lipochitooligosaccharide (nod factor) structure, whereas the products of the host-specific nod genes are necessary for diverse structural modifications, which vary in different rhizobium species. the sulfate group attached to the rhizobium meliloti nod signal is necessary for activity on the host plant alfalfa, while its absence renders the nod factor active on the non-host plant vetch. this substituent is th ... | 1995 | 7708710 |
| surface polysaccharide mutants of rhizobium sp. (acacia) strain grh2: major requirement of lipopolysaccharide for successful invasion of acacia nodules and host range determination. | two transposon tn5-induced mutants of wild-type broad-host-range rhizobium sp. grh2 were isolated and found to harbour different alterations in surface polysaccharides. these mutants, designated grh2-14 and grh2-50, induced a few, empty nodules on acacia and lost the ability to nodulate most host herbaceous legumes. whereas mutant grh2-14 produces an acidic exopolysaccharide (eps) similar to the wild-type, the acidic eps of mutant grh2-50 lacks galactose and the pyruvyl and 3-hydroxybutyryl subs ... | 1995 | 7711895 |
| synthesis of glycerophosphorylated cyclic (1,2)-beta-glucans in rhizobium meliloti strain 1021 after osmotic shock. | the transfer of phosphoglycerol moieties from phosphatidylglycerol to the cyclic (1,2)-beta-glucans in growing cultures of rhizobium meliloti strain 1021 was investigated using pulse-chase experiments with [3h]glycerol and/or [14c]glucose. no transfer occurred when cells were grown and pulse-chased in a medium containing 0.4 m nacl. however, radiolabelled glycerophosphorylated cyclic (1,2)-beta-glucans could be detected within 30 min after transfer of these cultures to a low-osmolarity medium. c ... | 1995 | 7711896 |
| the cychjkl genes of rhizobium meliloti involved in cytochrome c biogenesis are required for "respiratory" nitrate reduction ex planta and for nitrogen fixation during symbiosis. | we report the genetic and biochemical analysis of rhizobium meliloti mutants defective in symbiotic nitrogen fixation (fix-) and "respiratory" nitrate reduction (rnr-). the mutations were mapped close to the ade-1 and cys-46 chromosomal markers and the mutated locus proved to be identical to the previously described fix-14 locus. by directed tn5 mutagenesis, a 4.5 kb segment of the chromosome was delimited in which all mutations resulted in rnr- and fix- phenotypes. nucleotide sequence analysis ... | 1995 | 7715602 |
| the molecular basis of the host specificity of the rhizobium bacteria. | the interaction between soil bacteria belonging to the genera rhizobium, bradyrhizobium and azorhizobium and leguminous plants results in the induction of a new plant organ, the root nodule. after invading these root nodules via infection threads the bacteria start to fix atmospheric nitrogen into ammonia which is beneficial for the host plant. this symbiotic interaction is highly host-specific in that each rhizobial strain is able to associate with only a limited number of host plant species. t ... | 1994 | 7718036 |
| synthesis of "nod"-like chitin oligosaccharides by the xenopus developmental protein dg42. | the xenopus dg42 gene is expressed only between the late midblastula and neurulation stages of embryonic development. recent database searches show that dg42 has striking sequence similarity to the rhizobium nodc protein. nodc catalyzes the synthesis of chitin oligosaccharides which subsequently are transformed into bacterium-plant root signaling molecules. we find that the dg42 protein made in an in vitro coupled transcription-translation system catalyzes the synthesis of an array of chitin oli ... | 1995 | 7724589 |
| physicochemical properties of extracellular (1-->4)-beta-d-glucuronan produced by the rhizobium meliloti m5n1cs strain during fermentation: evidence of degradation by an exoenzyme activated by mg2+. | the mutant rhizobium meliloti m5n1cs (ncimb 40472) produced a partially acetylated (1-->4)-beta-d-glucuronan during fermentation. the polysaccharide (eps) extracted from broth during fermentation by microfiltration and ultrafiltration (using a 100 kda cut-off membrane) was characterized by size exclusion chromatography. the weight-average molecular weight (mw) of the eps decreased from 7.5 x 10(5) to 5 x 10(5) between 27 and 75 h of fermentation. when mgso4.7h2o (0.8 gl-1 per day) was present in ... | 1994 | 7727343 |
| plant isoflavonoids, pathogens and symbionts. | it has recently been discovered that when symbiotic rhizobium and bradyrhizobium cells are outside the plant they are also exposed to the isoflavonoid phytoalexins that are normally associated with pathogenic infections. how the symbionts elicit and respond to isoflavonoids may help to define the mechanisms that are used by other beneficial soil microorganisms to colonize plant roots. | 1995 | 7728386 |
| the rhizobium meliloti groelc locus is required for regulation of early nod genes by the transcription activator nodd. | the molecular chaperones related to groel (hsp60, cpn60) interact with partially folded proteins and appear to assist them to attain active and correctly folded conformation. they are required for cell viability but are probably more important for some processes than for others. through a random genetic search to find loci that are required for expression of the rhizobium meliloti nod (nodulation) genes, we isolated a mutant (b4) defective in luteolin-dependent activation of nod gene expression, ... | 1995 | 7729688 |
| sequence and distribution of is1312: evidence for horizontal dna transfer from rhizobium meliloti to agrobacterium tumefaciens. | two novel insertion sequences, is1312 and is1313, were found in ptibo542, the ti plasmid of agrobacterium tumefaciens strains bo542 and a281. nucleotide sequencing and southern hybridization revealed that is1312 and is1313 are homologous to rhizobium meliloti isrm1 and isrm2, respectively. is1312, isrm1, and another agrobacterium insertion sequence, is426, belong to the same is3 family of insertion sequences; however, is1312 is more closely related to the rhizobium isrm1 than it is to the agroba ... | 1995 | 7730290 |
| a new polyamine 4-aminobutylcadaverine. occurrence and its biosynthesis in root nodules of adzuki bean plant vigna angularis. | root nodules of adzuki bean plant (vigna angularis) contained a novel polyamine. the chemical structure of the new polyamine was determined to be nh2(ch2)5-nh(ch2)4nh2 (4-aminobutylcadaverine) based on gas chromatography-mass spectrometry. the occurrence of 4-aminobutylcadaverine was specific to the root nodules, since the unusual triamine was not detected in other organs of the adzuki bean plant. bacteroids, isolated from root nodules, contained both sym-homospermidine and 4-aminobutylcadaverin ... | 1995 | 7730376 |
| oxygen as a key developmental regulator of rhizobium meliloti n2-fixation gene expression within the alfalfa root nodule. | the symbiotic pattern of expression of rhizobium meliloti n2-fixation genes is tightly coupled with the histological organization of the alfalfa root nodule and thus is under developmental control. n2-fixation gene expression is induced very sharply at a particular zone of the nodule called interzone ii-iii that precedes the zone where n2 fixation takes place. we show here that this coupling can be disrupted, hereby resulting in ectopic expression of n2-fixation genes in the prefixing zone ii of ... | 1995 | 7731979 |
| identification of derivatized peptides without radiolabels: tandem mass spectrometric localization of the tagged active-site nucleophiles of two cellulases and a beta-glucosidase. | a new method that uses nonradioactive active site-directed enzyme inactivators and high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (hplc-esims/ms) to identify labeled peptides in a proteolytic digest is described. this method relies upon the fragmentation of labeled peptides in a predictable and reproducible manner in the collision cell of a tandem mass spectrometer. the exoglycanase from cellulomonas fimi, endoglucanase c from clostridium thermocellum, an ... | 1995 | 7733452 |
| canthaxanthin biosynthesis by the conversion of methylene to keto groups in a hydrocarbon beta-carotene by a single gene. | compounds that include (a) keto group(s) in a molecule are ubiquitous natural components. a novel gene involved in ketocompound biosynthesis, designated crtw, was isolated from the marine bacteria agrobacterium aurantiacum and alcaligenes pc-1 that produce ketocarotenoids such as astaxanthin. when this gene was introduced into escherichia coli that accumulated beta-carotene due to the erwinia carotenogenic genes, the e. coli transformants synthesized canthaxanthin, one of ketocarotenoids, which ... | 1995 | 7733978 |
| [agrobacterium radiobacter bacteremia. study of 2 cases and review of the literature]. | agrobacteria are small gramnegative bacilli which produce tumors in different vegetal species and occasionally are human pathogens. | 1995 | 7734495 |
| impaired photoassimilate partitioning caused by phloem-specific removal of pyrophosphate can be complemented by a phloem-specific cytosolic yeast-derived invertase in transgenic plants. | constitutive expression of the escherichia coli ppa gene encoding inorganic pyrophosphatase resulted in sugar accumulation in source leaves and stunted growth of transgenic tobacco plants. the reason for this phenotype was hypothesized to be reduced sucrose utilization and loading into the phloem. to study the role of ppi in phloem cells, a chimeric gene was constructed using the phloem-specific rolc promoter of agrobacterium rhizogenes to drive the expression of the ppa gene. removal of cytosol ... | 1995 | 7734961 |
| a full factorial analysis of nine factors influencing in vitro antagonistic screens for potential biocontrol agents. | the effect of nine factors on the outcome of classic in vitro screens testing the antagonistic action of endophytic bacterial isolates from grape vines against virulent agrobacterium vitis has been examined. these factors were (i) the strain of a. vitis, (ii) the strain of endophyte, (iii) the growth medium of the pathogen, (iv) the growth medium of the endophyte, (v) the temperature of growth of the pathogen, (vi) the temperature of growth of the endophyte, (vii) the ph of growth of the pathoge ... | 1995 | 7736357 |
| bradyrhizobium japonicum nodulation genetics. | studies of the genetics of nodulation by bradyrhizobium japonicum have revealed many similar features with rhizobium and azorhizobium species, but also apparent differences. the regulation of nod gene expression in b. japonicum is complex, involving the interplay of the positive regulator, nodd1, as well as a repressor, no1a. a unique feature of b. japonicum is the involvement of a two-component regulatory system, nodv and nodw, in the control of nod gene expression. it is not clear why b. japon ... | 1995 | 7737469 |
| the effect of l-tryptophane on yield of field bean and activity of soil microorganisms. | the pot trial was performed to study the effect of l-tryptophane (as an auxin precursor) applied in the amount 0.3 and 3.0 mg per 1 kg of the soil on yield and the chemical composition of field bean. the effects of this compound on dehydrogenases activity in the cells rhizobium leguminosarum isolated from root nodules, soil dehydrogenases activity and number of microorganisms from different systematic or physiological groups were also studied. the effects of l-tryptophane were compared to indole ... | 1994 | 7740988 |
| effects of synthetic bombyx mori cecropin b on the growth of plant pathogenic bacteria. | | 1995 | 7745285 |
| oxygen control in rhizobium. | rhizobia are gram-negative bacteria with two distinct habitats: the soil rhizosphere in which they have a saprophytic and, usually, aerobic life and a plant ecological niche, the legume nodule, which constitutes a microoxic environment compatible with the operation of the nitrogen reducing enzyme nitrogenase. the purpose of this review is to summarize the present knowledge of the changes induced in these bacteria when shifting to a microoxic environment. oxygen concentration regulates the expres ... | 1994 | 7747928 |
| the fnr family of transcriptional regulators. | homologues of the transcriptional regulator fnr from escherichia coli have been identified in a variety of taxonomically diverse bacterial species. despite being structurally very similar, members of the fnr family have disparate regulatory roles. those from shewanella putrefaciens, pseudomonas aeruginosa, pseudomonas stutzeri and rhodopseudomonas palustris are functionally similar to fnr in that they regulate anaerobic respiration or carbon metabolism. four rhizobial proteins (from rhizobium me ... | 1994 | 7747934 |
| expression of soybean nodulin 26 in transgenic tobacco. targeting to the vacuolar membrane and effects on floral and seed development. | nodulin 26 is an integral membrane protein of the symbiosome membrane of nitrogen-fixing soybean nodules. we expressed a nodulin 26 cdna in transgenic tobacco (tn26 tobacco) under the control of the cauliflower mosaic virus 35s promoter to study subcellular targeting and the physiological effect(s) of its expression. based on northern and western blots, the expression of nodulin 26 mrna and protein in transgenic plants is high in apical shoot sections, flowers, and stems, low in mature leaves, a ... | 1995 | 7749192 |
| marine algae that display anti-tumorigenic activity against agrobacterium tumefaciens. | thirty-five extracts representing different seasonal growths of 17 marine algal species collected from the alexandria coast were tested for anti-tumorigenic activity against agrobacterium tumefaciens galls on potato discs. eleven extracts (nine species) displayed > 20% inhibition of tumor initiation, with three of these (codium tomentosum, winter; jania rubens, summer; padina pavonia, winter) displaying relatively high activity. bacterial viability tests showed that the inhibitory effects were d ... | 1995 | 7750733 |
| cloning of the second adenylate cyclase gene (cya2) from rhizobium meliloti f34: sequence similarity to eukaryotic cyclases. | a second adenylate cyclase (cya2) gene was isolated from a rhizobium meliloti f34 gene bank. complemented e. coli delta cya mutants were capable of utilizing a number of, but not all, carbon sources known to be regulated by camp. dna hybridization studies showed cya2 to be unique to r. meliloti strains. the cya2 nucleotide sequence was determined and found to encode a protein of 363 amino acids. residues were identified within the c-terminal domain which are conserved in both eukaryotic adenylat ... | 1995 | 7750735 |
| the dnaa gene of rhizobium meliloti lies within an unusual gene arrangement. | rhizobium meliloti exists either as a free-living soil organism or as a differentiated endosymbiont bacteroid form within the nodules of its host plant, alfalfa (medicago sativa), where it fixes atmospheric n2. differentiation is accompanied by major changes in dna replication and cell division. in addition, r. meliloti harbors three unique large circular chromosome-like elements whose replication coordination may be complex. as part of a study of dna replication control in r. meliloti, we isola ... | 1995 | 7751302 |
| a homolog of the rhizobium meliloti nitrogen fixation gene fixn is involved in the production of a microaerobically induced oxidase activity in the phytopathogenic bacterium agrobacterium tumefaciens. | hybridization analysis using the rhizobium meliloti nitrogen fixation gene fixn as a probe revealed the presence of a homologous dna region in the phytopathogenic bacterium agrobacterium tumefaciens. hybridization signals were also detected with total dnas of rhizobium leguminosarum bv. phaseoli, rhodobacter capsulatus and escherichia coli, but not those of xanthomonas campestris pv. campestris and pseudomonas putida. the hybridizing fragment from a. tumefaciens was cloned and sequenced. the pre ... | 1995 | 7753030 |
| molecular analysis of the rhizobium meliloti mucr gene regulating the biosynthesis of the exopolysaccharides succinoglycan and galactoglucan. | the rhizobium meliloti tn5 mutant rm3131, producing galactoglucan (eps ii) instead of succinoglycan (eps i), was complemented by a 3.6-kb ecori-fragment of the rhizobium meliloti genome. sequencing of this fragment revealed six open reading frames (orfs). the orf found to be affected in the mutant rm3131 codes for a putative protein of 15.7 kda and forms a monocistronic transcriptional unit. further genetic analysis revealed that the gene mutated in rm3131 is identical to the previously describe ... | 1995 | 7756693 |
| novel ti plasmids in agrobacterium strains isolated from fig tree and chrysanthemum tumors and their opinelike molecules. | galls naturally induced on fig and chrysanthemum plants by strains of agrobacterium contained, in addition to other well-characterized opines such as nopaline, three tumor-specific opinelike molecules. these molecules were identified as deoxy-fructosyl-glutamine (dfg), deoxy-fructosyl-5-oxo-proline (dfop), and chrysopine (chilton et al., unpublished). strains isolated from fig tree and chrysanthemum tumors harbored different and unrelated ti plasmids as judged by hybridization with various vir a ... | 1995 | 7756696 |
| isolation and characterization of a locus from azospirillum brasilense sp7 that complements the tumorigenic defect of agrobacterium tumefaciens chvb mutant. | the chromosomal virulence gene chvb of agrobacterium tumefaciens is required for pathogenesis. a dna fragment from the chvb locus can hybridize to dna from azospirillum brasilense sp7. this dna fragment could restore the tumorigenic activity of the chvb mutant strain a. tumefaciens a1011 towards leaf disks of nicotiana tabacum. an nh2-terminal open reading frame, 480 codons long, was most likely responsible for the restoration of the tumorigenic activity. the a. brasilense sequence showed good h ... | 1995 | 7756697 |
| divergent transcription and a remote operator play a role in control of expression of a nopaline catabolism promoter in agrobacterium tumefaciens. | the nocp-nocr divergent gene arrangement of the nopaline catabolism (noc) operon of the agrobacterium tumefaciens ti plasmid ptit37 was examined with respect to the expression of the nocp promoter. under repressive conditions, i.e. in the absence of nopaline, four distinct levels of pnocp expression were observed. the lowest level of expression, i.e. full repression, was detected in the presence of the nocr repressor, together with the remote noc operator and productive transcription from the di ... | 1995 | 7759474 |
| study of parameters affecting poly(3-hydroxybutyrate) quantification by gas chromatography. | poly(3-hydroxybutyrate) (phb) quantification has been developed mostly using acidic methanolysis followed by gc analysis of the 3-hydroxybutyrate methyl ester. however, under our experimental conditions, only 62% of the ester was detected by gc analysis. following the study of the different steps involved in this method (i.e., hydrolysis, esterification, and recovery of the ester), the recovery was shown to be limiting. addition of water to the organic phase, required for its purification before ... | 1995 | 7762788 |
| novel narrow-host-range vectors for direct cloning of foreign dna in pseudomonas. | narrow-host-range vectors, based on an indigenous replicon and containing a multiple cloning site, have been constructed in a pseudomonas host capable of growth on unusual substrates. the new cloning vectors yield sufficient amounts of dna for preparative purposes and belong to an incompatibility group different from that of the incp and incq broad-host-range vectors. one of these vectors, named pdb47f, was used to clone, directly in pseudomonas, dna fragments from agrobacterium, pseudomonas, an ... | 1994 | 7764307 |
| nucleotide sequence of the rol region of the mikimopine-type root-inducing plasmid pri1724. | the rol genes of root-inducing plasmids (pri) are essential for tumorigenesis on various dicotyledonous plants. the nucleotide sequences of the rol genes together with their flanking regions from the mikimopine-type pri1724 were analyzed and compared with the corresponding portions of the agropine-type pria4 and the mannopine-type pri8196 that were previously reported [slightom et al., j. biol. chem., 261, 108-121 (1986); hansen et al., proc. natl. acad. sci. u.s.a., 88, 7763-7767 (1991)]. the s ... | 1994 | 7764693 |
| transgenic tomato plants expressing the tomato yellow leaf curl virus capsid protein are resistant to the virus. | the tomato yellow leaf curl virus (tylcv) gene that encodes the capsid protein (v1) was placed under transcriptional control of the cauliflower mosaic virus 35s promoter and cloned into an agrobacterium ti-derived plasmid and used to transform plants from an interspecific tomato hybrid, lycopersicon esculentum x l. pennellii (f1), sensitive to the tylcv disease. when transgenic f1 plants, expressing the v1 gene, were inoculated with tylcv using whiteflies fed on tylcv-infected plants, they respo ... | 1994 | 7764709 |
| genetic regulation in plant pathogenic pseudomonads. | | 1994 | 7765196 |
| rapid purification of ti plasmids from agrobacterium by ethidium bromide treatment and phenol extraction. | an efficient method is described for the purification of ti plasmid dna from agrobacterium. the procedure is based on the relative binding capacity of ethidium bromide to supercoiled plasmid dna and linear dna and on the high solubility of ethidium bromide in phenol. following treatment with ethidium bromide, more than 87% of linear chromosomal dna and most of the rna was present in the phenol phase, while 91% of ti plasmid dna was recovered from the aqueous phase. the ti plasmid dna was suffici ... | 1993 | 7765300 |
| construction of a single-transposon-insertion mutant in rhizobium sp. strain tal1145 from a double-insertion mutant. | a method for developing a single-transposon-insertion mutant from a double-insertion mutant in rhizobium is described. an exopolysaccharide (eps)-defective mutant containing two tn5-lacz insertions was complemented with cloned wild-type dna for eps synthesis. one of the tn5-lacz insertions from the mutant was transferred to the complementing plasmid by homologous recombination. the plasmid containing the tn5-lacz insertion in the gene involved in eps synthesis was transferred into the wild-type ... | 1994 | 7765390 |
| phosphodiesterase and phosphotriesterase in rhizobium and bradyrhizobium strains and their roles in the degradation of organophosphorus pesticides. | of 13 rhizobium and bradyrhizobium strains investigated for the production of cellular and extracellular phosphodiesterase and phosphotriesterase, all were found to produce both enzymes. phosphodiesterase was produced at a much higher level than phosphotriesterase. rhizobium meliloti tal 1373 was the most productive. the extracellular enzymes were activated by inclusion in the assay mixture of ca2+ or mg2+. the enzymes were inhibited by zn2+ but not significantly affected by cu2+, co2+ and mn2+. ... | 1994 | 7765398 |
| production of a bioflocculant by mixed culture. | colony groups that form large amounts of slime externally were obtained from activated sludge among phthalate-assimilating microbes. that slime, which r-3 mixed microbes produced externally, had a high level of flocculation activity. r-3 mixed strains, one of such colony groups, efficiently produced a bioflocculant (apr-3) in liquid cultures of production medium, especially that containing starch and glucose (1:1) as carbon sources. identification of this group of bioflocculant-producing microbe ... | 1994 | 7765478 |
| cellular localization and functional analysis of the protein encoded by the chromosomal virulence gene(acvb) of agrobacterium tumefaciens. | a chromosomal virulence gene, acvb, of agrobacterium tumefaciens [j. bacteriol., 175, 3208-3212 (1993)] was over-expressed in escherichia coli. a 47-kda protein was produced and localized in the periplasmic space of e. coli. amino acid sequence analysis of its n-terminal demonstrated that a signal peptide of 24 amino acids was cleaved from the pre acvb protein to produce the mature 47-kda protein. western-blot analysis using the antiserum against the acvb protein detected a 47-kda protein in the ... | 1994 | 7765595 |
| sensitivity of selected bacterial species to uv radiation. | the effect of exposure of bacterial suspensions to uv radiation by means of the dose-response curves was assessed. the d37 and d10 values were used for subsequent statistical analysis of the results. the aim of this article is to evaluate the sensitivity to uv radiation of several microorganisms of different habitats (rhizobium meliloti, rhodobacter sphaeroides, escherichia coli, and deinococcus radiodurans), two mutants with nonfunctional sos dna repair system (r. meliloti reca- and e. coli rec ... | 1995 | 7765851 |
| use of a polymerase-chain-reaction-amplified dna probe from pseudomonas putida to detect d-hydantoinase-producing microorganisms by direct colony hybridization. | pseudomonas putida strain dsm 84 produces n-carbamyl-d-amino acids from the corresponding d-5-monosubstituted hydantoins. the sequence of the d-hydantoinase gene from this strain (genbank accession number l24157) was used to develop a dna probe of 122 base pairs (bp) that could detect d-hydantoinase genes in other bacterial genera by dna and by colony hybridization. under conditions tolerating 32% mismatch, the probe was specific for all strains that expressed d-hydantoinase activity. these incl ... | 1995 | 7766091 |
| long-term effects of metals in sewage sludge on soils, microorganisms and plants. | this paper reviews the evidence for impacts of metals on the growth of selected plants and on the effects of metals on soil microbial activity and soil fertility in the long-term. less is known about adverse long-term effects of metals on soil microorganisms than on crop yields and metal uptake. this is not surprising, since the effects of metals added to soils in sewage sludge are difficult to assess, and few long-term experiments exist. controlled field experiments with sewage sludges exist in ... | 1995 | 7766215 |
| modification of brassica napus seed oil by expression of the escherichia coli fabh gene, encoding 3-ketoacyl-acyl carrier protein synthase iii. | the escherichia coli fabh gene encoding 3-ketoacyl-acyl carrier protein synthase iii (kas iii) was isolated and the effect of overproduction of bacterial kas iii was compared in both e. coli and brassica napus. the change in fatty acid profile of e. coli was essentially the same as that reported by tsay et al. (j biol chem 267 (1992) 6807-6814), namely higher c14:0 and lower c18:1 levels. in our study, however, an arrest of cell growth was also observed. this and other evidence suggests that in ... | 1995 | 7766878 |