Outer membrane proteins of Fibrobacter succinogenes with potential roles in adhesion to cellulose and in cellulose digestion

Comparative analysis of binding of intact glucose-grown Fibrobacter succinogenes strain S85 cells and adhesion-defective mutants AD1 and AD4 to crystalline and acid-swollen (amorphous) cellulose showed that strain S85 bound efficiently to both forms of cellulose while mutant Ad1 bound to acid-swollen cellulose, but not to crystalline cellulose, and mutant Ad4 did not bind to either. One- and two-dimensional electrophoresis (2-DE) of outer membrane cellulose binding proteins and of outer membranes, respectively, of strain S85 and adhesion-defective mutant strains in conjunction with mass spectrometry analysis of tryptic peptides was used to identify proteins with roles in adhesion to and digestion of cellulose. Examination of the binding to cellulose of detergent-solubilized outer membrane proteins from S85 and mutant strains revealed six proteins in S85 that bound to crystalline cellulose that were absent from the mutants and five proteins in Ad1 that bound to acid-swollen cellulose that were absent from Ad4. Twenty-five proteins from the outer membrane fraction of cellulose-grown F. succinogenes were identified by 2-DE, and 16 of these were up-regulated by growth on cellulose compared to results with growth on glucose. A protein identified as a Cl-stimulated cellobiosidase was repressed in S85 cells growing on glucose and further repressed in the mutants, while a cellulose-binding protein identified as pilin was unchanged in S85 grown on glucose but was not produced by the mutants. The candidate differential cellulose binding proteins of S85 and the mutants and the proteins induced by growth of S85 on cellulose provide the basis for dissecting essential components of the cellulase system of F. succinogenes.     

Fiber-degrading systems of different strains of the genus Fibrobacter

The S85 type strain of Fibrobacter succinogenes, a major ruminal fibrolytic species, was isolated 49 years ago from a bovine rumen and has been used since then as a model for extensive studies. To assess the validity of this model, we compared the cellulase- and xylanase-degrading activities of several other F. succinogenes strains originating from different ruminants, including recently isolated strains, and looked for the presence of 10 glycoside hydrolase genes previously identified in S85. The NR9 F. intestinalis type strain, representative of the second species of the genus, was also included in this study. DNA-DNA hybridization and 16S rRNA gene sequencing first classified the strains and provided the phylogenetic positions of isolates of both species. Cellulase and xylanase activity analyses revealed similar activity profiles for all F. succinogenes strains. However, the F(E) strain, phylogenetically close to S85, presented a poor xylanolytic system and weak specific activities. Furthermore, the HM2 strain, genetically distant from the other F. succinogenes isolates, displayed a larger cellulolytic profile on zymograms and higher cellulolytic specific activity. F. intestinalis NR9 presented a higher cellulolytic specific activity and a stronger extracellular xylanolytic activity. Almost all glycoside hydrolase genes studied were found in the F. succinogenes isolates by PCR, except in the HM2 strain, and few of them were detected in F. intestinalis NR9. As expected, the fibrolytic genes of strains of the genus Fibrobacter as well as the cellulase and xylanase activities are better conserved in closely related phylogenetic isolates.     

A comparative study of the IgG-binding components of the membrane in different strains of Staphylococcus aureus using the indirect hemagglutination reaction and an immunofluorescence method

A comparative estimation of IgG-binding activity of 85 S. aureus clinical strains was carried out by the method of indirect hemagglutination reaction. The S. aureus strain selected as a result of screening was found to exceed by more than an order the Cowan I strain obtained from the L. A. Tarasevich State Institute of Standards and Control of the Medical Biological Drugs in the IgG-binding activity. It was established that the ratio of two types of IgG-binding sites located on the S. aureus surface, varied depending on the strain, composition and quality (liquid or solid) of the culture medium.     

The hydrolysis of lucerne cell-wall monosaccharide components by monocultures or pair combinations of defined ruminal bacteria

The defined ruminal bacterial strains Fibrobacter succinogenes S85, Ruminococcus flavefaciens FD1, Ruminococcus albus 7, Butyrivibrio fibrisolvens D1, and Bacteroides ruminicola GA33 were grown, in monocultures or as combinations of pair strains, on isolated lucerne cell-walls (CW) as the sole carbohydrate substrate. Fibrobacter succinogenes S85 was the dominant strain determining extent of CW hydrolysis in all combinations with S85. The hydrolysis of cellulose, xylan, hemicellulose side-sugars, and total CW monosaccharides by pure S85 were: 58.8, 47.3, 66.9 and 57.0%, respectively. The strains combination S85 plus D1 comprised the highest complementary effect, increasing significantly the hydrolysis of cellulose and total CW monosaccharides by 16% and 13%, respectively, above the values obtained by pure S85. This complementation was expressed also in growth pattern of bacteria. The monocultures of FD1, D1 and GA33 had very little hydrolytic effect on lucerne cellulose, but higher effects on xylan and hemicellulose side-sugars. The combinations D1 plus GA33 and 7 plus GA33 were complementary in the hydrolysis of all CW polysaccharides. The combinations FD1 plus D1, FD1 plus GA33, and 7 plus D1 were complementary only with respect to hemicellulose hydrolysis. On the other hand, the cellulolytic combinations S85 plus FD1, S85 plus 7 and FD1 plus 7 demonstrated negative interactions in lucerne CW polysaccharides hydrolysis. Under scanning electron microscopy (SEM), S85 comprised the most dense layer of bacterial cell mass attached to and colonized on CW particles. The cell surface topology of the cellulolytic strains S85, FD1 and 7 attached to CW particles was specified by a coat of characteristic protuberant structures.     

The hydrolysis of lucerne cell-wall monosaccharide components by monocultures or pair combinations of defined ruminal bacteria

The defined ruminal bacterial strains Fibrobacter succinogenes S85, Ruminococcus flavefaciens FD1, Ruminococcus albus 7, Butyrivibrio fibrisolvens D1, and Bacteroides ruminicola GA33 were grown, in monocultures or as combinations of pair strains, on isolated lucerne cell-walls (CW) as the sole carbohydrate substrate. Fibrobacter succinogenes S85 was the dominant strain determining extent of CW hydrolysis in all combinations with S85. The hydrolysis of cellulose, xylan, hemicellulose side-sugars, and total CW monosaccharides by pure S85 were: 58·8, 47·3, 66·9 and 57·0%, respectively. The strains combination S85 plus D1 comprised the highest complementary effect, increasing significantly the hydrolysis of cellulose and total CW monosaccharides by 16% and 13%, respectively, above the values obtained by pure S85. This complementation was expressed also in growth pattern of bacteria.
The monocultures of FD1, D1 and GA33 had very little hydrolytic effect on lucerne cellulose, but higher effects on xylan and hemicellulose side-sugars. The combinations D1 plus GA33 and 7 plus GA33 were complementary in the hydrolysis of all CW polysaccharides. The combinations FD1 plus D1, FD1 plus GA33, and 7 plus D1 were complementary only with respect to hemicellulose hydrolysis. On the other hand, the cellulolytic combinations S85 plus FD1, S85 plus 7 and FD1 plus 7 demonstrated negative interactions in lucerne CW polysaccharides hydrolysis.
Under scanning electron microscopy (SEM), S85 comprised the most dense layer of bacterial cell mass attached to and colonized on CW particles. The cell surface topology of the cellulolytic strains S85, FD1 and 7 attached to CW particles was specified by a coat of characteristic protuberant structures.     

Characterization of Staphylococcus aureus in a Pediatric Burn Unit

A one-year study on an endemic strain of Staphylococcus aureus phage type 84/85 in a children's burn unit is described. The endemic strain rapidly colonized the burns and nares of acute patients after admission but was not isolated from a patient on admission. Nonendemic strains of S. aureus found on some new patients were mostly non-phage typable and did not prevail in burns. The endemic strain was rarely isolated from the nares and skin of reconstructive patients or from the nares of hospital personnel. The endemic strain did colonize the oral cavity, normal skin, and intestinal tract of some acute patients. Endemic and nonendemic strains of S. aureus from the burned children were compared in their biochemical activities and antibiotic sensitivities to two groups of S. aureus from one other local and one Danish burns unit. The latter groups of strains represented different combinations of staphylococcal phage group III strains. Each of the four groups of strains differed in production of hemolysins, Tween 80 hydrolysis, egg yolk reaction, and proteolysis of casein and gelatin. All of the strains were uniformly sensitive to gentamicin, oxacillin, and cephalothin. Only 4 of 162 strains tested were methicillin resistant. The endemic S. aureus strains of phage type 84/85 were uniformly resistant to eight other antibiotics including lincomycin and clindamycin. The endemic strain was not the known cause of a clinically documented infection in a group of 82 acute patients studied. The possible role of S. aureus strains of phage group III in burn grafting problems is discussed.     

Novel DNA sequences from natural strains of the nitrogen-fixing symbiotic bacterium Sinorhizobium meliloti

Variation in genome size and content is common among bacterial strains. Identifying these naturally occurring differences can accelerate our understanding of bacterial attributes, such as ecological specialization and genome evolution. In this study, we used representational difference analysis to identify potentially novel sequences not present in the sequenced laboratory strain Rm1021 of the nitrogen-fixing bacterium Sinorhizobium meliloti. Using strain Rm1021 as the driver and the type strain of S. meliloti ATCC 9930, which has a genome size approximately 370 kilobases bigger than that of strain Rm1021, as the tester, we identified several groups of sequences in the ATCC 9930 genome not present in strain Rm1021. Among the 85 novel DNA fragments examined, 55 showed no obvious homologs anywhere in the public databases. Of the remaining 30 sequences, 24 contained homologs to the Rm1021 genome as well as unique segments not found in Rm1021, 3 contained sequences homologous to those published for another S. meliloti strain but absent in Rm1021, 2 contained sequences homologous to other symbiotic nitrogen-fixing bacteria (Rhizobium etli and Bradyrhizobium japonicum), and 1 contained a sequence homologous to a gene in a non-nitrogen-fixing species, Pseudomonas sp. NK87. Using PCR, we assayed the distribution of 12 of the above 85 novel sequences in a collection of 59 natural S. meliloti strains. The distribution varied widely among the 12 novel DNA fragments, from 1.7% to 72.9%. No apparent correlation was found between the distribution of these novel DNA sequences and their genotypes obtained using multilocus enzyme electrophoresis. Our results suggest potentially high rates of gene gain and loss in S. meliloti genomes.     

Clostridium saccharogumia sp. nov. and Lactonifactor longoviformis gen. nov., sp. nov., two novel human faecal bacteria involved in the conversion of the dietary phytoestrogen secoisolariciresinol diglucoside

Two anaerobic bacteria involved in the conversion of the plant lignan secoisolariciresinol diglucoside were isolated from faeces of a healthy male adult. The first isolate, strain SDG-Mt85-3Db, was a mesophilic strictly anaerobic Gram-positive helically coiled rod. Based on 16S r RNA gene sequence analysis, its nearest relatives were Clostridium cocleatum (96.7% similarity) and Clostridium ramosum (96.6%). In contrast to these species, the isolate was devoid of alpha-galactosidase and -glucosidase and did not grow on maltose, melibiose, raffinose, rhamnose and trehalose. The hypothesis that strain SDG-Mt85-3Db represents a new bacterial species of the Clostridium cluster XVIII was confirmed by DNA-DNA hybridisation experiments. The G+C content of DNA of strain SDG-Mt85-3Db (30.7+/-0.8 mol%) was comparable with that of Clostridium butyricum, the type species of the genus Clostridium. The name Clostridium saccharogumia is proposed for strain SDG-Mt85-3Db (=DSM 17460T=CCUG 51486T). The second isolate, strain ED-Mt61/PYG-s6, was a mesophilic strictly anaerobic Gram-positive regular rod. Based on 16S rRNA gene sequence analysis, its nearest relatives were Clostridium amygdalinum (93.3%), Clostridium saccharolyticum (93.1%) and Ruminococcus productus (93.0%). The isolate differed from these species in its ability to dehydrogenate enterodiol. It also possessed alpha-arabinosidase and -galactosidase and had a higher G+C content of DNA (48.0 mol%). According to these findings, it is proposed to create a novel genus, Lactonifactor, and a novel species, Lactonifactor longoviformis, to accommodate strain ED-Mt61/PYG-s6. The type strain is DSM 17459T (=CCUG 51487T).     

Prevalence of emm1 Streptococcus pyogenes having a novel type of genomic composition

Streptococcus pyogenes is a causative agent of streptococcal toxic shock syndrome (STSS). The complete genome sequence of a S. pyogenes strain 10–85 isolated from a STSS patient was recently announced. In this study, the genome sequence was dissected and it was found that the genomic region around 200 kbp (region A) and the genomic region around 1600 kbp (region B) were replaced by each other in strain 10–85, when compared with those in reference strains SF370 and A20. In order to address whether this replacement is unique to 10–85, we further analyzed 163 emm1‐type strains. The results indicated that none of the strains isolated before 1990 had the replacement. In contrast, most of the strains isolated at least after 2000 appeared to have the 10–85‐type replacement.     

Ochrovirga pacifica gen. nov., sp. nov., A Novel Agar-Lytic Marine Bacterium of the Family Flavobacteriaceae Isolated From A Seaweed

A strain designated as S85^T was isolated from a seaweed collected from coastal area of Chuuk State in Micronesia. The strain was gram-negative, rod-shaped, and non-motile and formed yellow colonies on the SWY agar (0.2 % yeast extract and 1.5 % agar in seawater) and Marine agar 2216. The strain grew at pH 5–9 (optimum, pH 8), at 15–40 °C (optimum, 25–28 °C), and with 1–9 % (w/v) NaCl (optimum, 3 %). The phylogenetic analysis based on 16S rRNA gene sequence showed that strain S85^T was related to Lutibacter litoralis CL-TF09^T and Maritimimonas rapanae A31^T with 91.4 % and with 90.5 % similarity, respectively. The dominant fatty acids were iso-C_15:0, iso-C_15:0 3-OH and iso-C_17:0 3-OH, C_16:0 3-OH and summed feature 3 (C_16:1 ω7c and/or iso-C_15:0 2-OH). The major isoprenoid quinone was MK-6. The DNA G+C content of the type strain was 34.6 mol %. The major polar lipids were phosphatidylethanolamine, an unknown glycolipid and two unknown polar lipids. Based on this polyphasic taxonomic data, strain S85^T stands for a novel species of a new genus, and we propose the name Ochrovirga pacifica gen. nov., sp. nov. The type strain of O. pacifica is S85^T (=KCCM 90106 =JCM 18327^T).     

The combined effects of plasma and hydrogel coating on adhesion of Staphylococcus epidermidis and Staphylococcus aureus to polyurethane catheters

Abstract The adhesion of three Staphylococcus epidermidis and three S. aureus clinical isolates, to uncoated and hydrogel-coated polyurethane catheters was tested, following pretreatment of catheters with human plasma. Plasma significantly decreased the adhesion of S. epidermidis strains to uncoated polyurethane catheters, but had no significant effect on the adhesion to hydrogel-coated catheters. The influence of plasma on adhesion of S. aureus strains to catheters was strain dependent. Plasma significantly increased the adhesion of one strain (SA6) to uncoated catheters. For two other strains (SA3 and SA14) plasma produced no clear effect on their adhesion to uncoated catheters; adhesion values for each strain showed either a small but significant increase or a replicate-dependent increase or decrease. However, plasma significantly increased the adhesion of all S. aureus strains to hydrogel-coated polyurethane catheters. Overall, with the exception of one batch culture of S. epidermidis strain SE3 tested, attachment to plasma-treated hydrogel-coated catheters was statistically significantly lower, by up to 85%, than attachment to plasma-treated uncoated catheters for both S. epidermidis and S. aureus .     

Extracellular beta-galactosidase activity of a Fibrobacter succinogenes S85 mutant able to catabolize lactose

Fibrobacter succinogenes S85 is unable to grow with lactose as the source of carbohydrate, although it does exhibit low beta-galactosidase (EC 3.2.1.23) activity. Spontaneous mutants of strain S85 able to grow on lactose were isolated after spreading cells on a chemically defined agar medium with lactose as the carbohydrate source. A lactose-catabolizing isolate, designated L2, exhibited a sodium dodecyl sulfate-polyacrylamide gel electrophoresis protein profile and an immunoblot profile with polyclonal antibodies to whole cells of S85 which were identical to those observed for S85. Strain L2 exhibited both cell-associated and extracellular beta-galactosidase activity with either p-nitrophenyl-beta-D-galactopyranoside or lactose as the substrate. The cell-associated enzyme exhibited the greatest activity in the periplasmic space. Enzyme production was partially inhibited by glucose. The beta-galactosidase was activated by divalent cations and exhibited a pH optimum of 6.5. Analysis of the extracellular culture fluid revealed that glucose derived from the hydrolysis of lactose was used for growth, but galactose was not metabolized further. Cells were unable to take up the lactose analog, methyl-beta-D-thiogalactopyranoside. These data suggest that beta-galactosidase of F. succinogenes L2 cleaves lactose outside the cells and that the glucose released is catabolized while the galactose accumulates in the extracellular culture fluid.     

Extracellular beta-galactosidase activity of a Fibrobacter succinogenes S85 mutant able to catabolize lactose.

Fibrobacter succinogenes S85 is unable to grow with lactose as the source of carbohydrate, although it does exhibit low beta-galactosidase (EC 3.2.1.23) activity. Spontaneous mutants of strain S85 able to grow on lactose were isolated after spreading cells on a chemically defined agar medium with lactose as the carbohydrate source. A lactose-catabolizing isolate, designated L2, exhibited a sodium dodecyl sulfate-polyacrylamide gel electrophoresis protein profile and an immunoblot profile with polyclonal antibodies to whole cells of S85 which were identical to those observed for S85. Strain L2 exhibited both cell-associated and extracellular beta-galactosidase activity with either p-nitrophenyl-beta-D-galactopyranoside or lactose as the substrate. The cell-associated enzyme exhibited the greatest activity in the periplasmic space. Enzyme production was partially inhibited by glucose. The beta-galactosidase was activated by divalent cations and exhibited a pH optimum of 6.5. Analysis of the extracellular culture fluid revealed that glucose derived from the hydrolysis of lactose was used for growth, but galactose was not metabolized further. Cells were unable to take up the lactose analog, methyl-beta-D-thiogalactopyranoside. These data suggest that beta-galactosidase of F. succinogenes L2 cleaves lactose outside the cells and that the glucose released is catabolized while the galactose accumulates in the extracellular culture fluid.     

Novel DNA Sequences from Natural Strains of the Nitrogen-Fixing Symbiotic Bacterium Sinorhizobium meliloti

Variation in genome size and content is common among bacterial strains. Identifying these naturally occurring differences can accelerate our understanding of bacterial attributes, such as ecological specialization and genome evolution. In this study, we used representational difference analysis to identify potentially novel sequences not present in the sequenced laboratory strain Rm1021 of the nitrogen-fixing bacterium Sinorhizobium meliloti. Using strain Rm1021 as the driver and the type strain of S. meliloti ATCC 9930, which has a genome size ~370 kilobases bigger than that of strain Rm1021, as the tester, we identified several groups of sequences in the ATCC 9930 genome not present in strain Rm1021. Among the 85 novel DNA fragments examined, 55 showed no obvious homologs anywhere in the public databases. Of the remaining 30 sequences, 24 contained homologs to the Rm1021 genome as well as unique segments not found in Rm1021, 3 contained sequences homologous to those published for another S. meliloti strain but absent in Rm1021, 2 contained sequences homologous to other symbiotic nitrogen-fixing bacteria (Rhizobium etli and Bradyrhizobium japonicum), and 1 contained a sequence homologous to a gene in a non-nitrogen-fixing species, Pseudomonas sp. NK87. Using PCR, we assayed the distribution of 12 of the above 85 novel sequences in a collection of 59 natural S. meliloti strains. The distribution varied widely among the 12 novel DNA fragments, from 1.7% to 72.9%. No apparent correlation was found between the distribution of these novel DNA sequences and their genotypes obtained using multilocus enzyme electrophoresis. Our results suggest potentially high rates of gene gain and loss in S. meliloti genomes.     

Effect of fermented milk intake on plasmid transfer and on the persistence of transconjugants in the digestive tract of gnotobiotic mice

Plasmid transfer occurs in the digestive tract and the transconjugants may become durably established. The aim of the present work is to investigate the effect of probiotics on plasmid transfer and on establishment of transconjugants in the gut. Plasmid transfers were carried out in the digestive tract of germ free mice associated with an E. coli K12 donor strain harboring three plasmids (R388, self-transmissible, pCE325 and pUB2380, mobilisable,) and an E. coli recipient strain, PG1, of human origin (Duval-Iflah et al., 1994). Milks fermented with either Lactobacillus bulgaricus or Streptococcus thermophilus or symbiosis, S85, of both strains were given daily as 1/3 of food diet. Fermented milks have no effect on the transfer of R388 and pUB2380 except a slight increase of TC(R388) with milk fermented with S85. Long term ingestion of milk fermented with S85 inhibited the formation and the establishment of transconjugants TC(pCE325). Milk fermented with L. bulgaricus lowered the population density of TC(pCE325) in animals where they were already established. This phenomenon was reversible, since the density of TC(pCE325) increased in the same animals after cessation of supplementation. Bacterial cultures obtained in MRS broth and given in state of drinking water were compared with fermented milks. Bacterial cultures with L. bulgaricus and with S85 favoured the establishment of TC(pCE325). These results indicate for the first time that probiotics have various effects on the formation and/or establishment of transconjugants in the gut of axenic mice. The effects depend on whether the probiotics were cultivated in milk or in MRS, indicating that bacterial metabolites and viable bacteria can be involved.     

Degradation of polyester polyurethane by newly isolated Pseudomonas aeruginosa strain MZA-85 and analysis of degradation products by GC–MS

In this report, a polyester polyurethane (PU) degrading bacterium, designated as strain MZA-85, was isolated from soil through enrichment. The bacterium was identified through 16S rRNA gene sequencing; it was completely matched with Pseudomonas aeruginosa type strain. The degradation of PU film pieces by P. aeruginosa strain MZA-85 was investigated by scanning electron microscopy (SEM), Fourier transformed infra-red spectroscopy (FT-IR) and gel permeation chromatography (GPC). SEM micrographs of PU film pieces, treated with strain MZA-85, revealed changes in the surface morphology. FTIR spectrum showed increase in organic acid functionality and corresponding decrease in ester functional group. GPC results revealed increase in polydispersity, which shows that long chains of polyurethane polymer are cleaved into shorter chains by microbial action. The bacterium was found to produce cell associated esterases based on p-Nitrophenyl acetate (pNPA) hydrolysis assay. 1,4-Butanediol and adipic acid monomers were detected by gas chromatography–mass spectrometry (GC–MS), which were produced as a result of hydrolysis of ester linkages in PU by cell bound esterases. Strain MZA-85 not only depolymerized PU but also mineralized it into CO₂ and H₂O, as indicated by increase in cells growth in the presence of degradation products as well as detection of CO₂ evolution through Sturm test. From the results presented above, it is finally concluded that P. aeruginosa strain MZA-85, as well as its enzymes, can be applied in the process of biochemical monomerization for the pure monomers recycling.     

The pyocin Sa receptor of Pseudomonas aeruginosa is associated with ferripyoverdin uptake.

We have used Tn5 mutagenesis to obtain a mutant resistant to pyocin Sa. When grown in iron-deficient succinate medium this mutant lacked an 85-kDa iron-regulated outer membrane protein (IROMP), and expression of a 75-kDa IROMP was increased compared with that in the parent strain. The mutant was deficient in pyoverdin biosynthesis and showed a 95% decrease in transport of ferripyoverdin purified from the parent strain, suggesting that the 85-kDa IROMP is the specific receptor for ferripyoverdin and pyocin Sa. The mutant compensated for the deficiency in pyoverdin biosynthesis and transport by exhibiting a fourfold increase in ferripyochelin transport. The low-level transport of ferripyoverdin in the Sa-resistant mutant, which extended to heterologous pyoverdins from other strains, suggests that Pseudomonas aeruginosa has a second ferripyoverdin uptake system of lower affinity and broader specificity.     

Characterization of large plasmids encoding resistance to toxic heavy metals in Salmonella abortus equi

Salmonella abortus equi vaccine strains were found to be resistant to high levels of toxic heavy metals--arsenic, chromium, cadmium, and mercury. The two strains 157 and 158 were resistant to ampicillin also. Curing of these strains resulted in loss of one or more resistance marker indicating plasmid borne resistance. Plasmid profile of strain 157 showed presence of three plasmids of 85, 54, and 0.1 Kb, whereas 158 strain showed presence of 85 Kb and 2 Kb plasmids. Plasmids were isolated from strain 157 and introduced into E. coli DH5alpha with a transformation efficiency of 2 x 10(3) transformants/microg DNA. Interestingly the transformants were resistant to antibiotics, heavy metals (As, Cr, Cd, Hg) and was also able to utilize citrate, a trait specific to Salmonella species. We report and establish for the first time the transferable large plasmids encoding resistance to various heavy metals, antibiotics and biochemical nature of S. abortus equi.     

Uptake of Pyocin S3 Occurs through the Outer Membrane Ferripyoverdine Type II Receptor of Pseudomonas aeruginosa

Pyocin S3 was found to kill exclusively Pseudomonas aeruginosa isolates producing type II pyoverdine (exemplified by strain ATCC 27853). Killing was specifically inhibited by addition of type II ferripyoverdine. All Tn5 mutants resistant to pyocin S3 were defective for pyoverdine-mediated iron uptake and failed to produce an 85-kDa iron-repressed outer membrane protein. We conclude that this protein is probably the type II ferripyoverdine receptor that is used by pyocin S3 to gain entry into the cell.