Strains Of Streptococcus Bovis Research Articles

Administration of Streptococcus bovis isolated from sheep rumen digesta on rumen function and physiology as evaluated in a rumen simulation technique system.

Background and Aim:Little information about the stability and changes of sheep ruminal microbiota due to pathogen intervention in the rumen simulation technique (RUSITEC) is available. This study aimed to investigate the effect of administration of a novel isolated Streptococcus bovis strain on rumen microbiology and physiology. In addition, the isolation of pigment-producing Streptococcus lutetiensis is described.Materials and Methods:Microbial strains were isolated from sheep rumen digesta. An isolated strain of S. bovis was evaluated in the RUSITEC system fed with mixed cattle feed and compared with an in-house developed probiotic formulation (PF), PF 1, containing Bacillus amyloliquifaciens, Bacillus subtilis, and Propionibacterium freudenreichii. The parameters of volatile fatty acid, lactic acid, pH profiling, and the coliform anti-pathogenicity were evaluated to determine the effect of S. bovis on rumen function and physiology.Results:Administration of S. bovis reduced the coliform count by 31.20% from 7.2×1010 colony-forming units (CFU)/mLto 1.7×106 CFU/mL. Agar diffusion assays revealed the extracellular antimicrobial activity of S. bovis against coliforms; Escherichia coli and Salmonella enterica with 12 and 14 mm zones of inhibition, respectively. Simultaneously, an increase of 61.62% in the rumen yeast count was noted. The physiological changes resulted in a 5% reduction in acetic acid concentration from 431 to 405 mg/L.Conclusion:The present research indicates that S. bovis is highly capable of altering rumen physiology and function on colonization and is a key transition microbe to be studied during rumen intervention studies. A decrease in the coliform count could be attributed to extracellular production of a bacteriocin-like substance, as illustrated through agar diffusion assays.

Dairy propionibacteria as direct-fed microbials: in vitro effect on acid metabolism of Streptococcus bovis and Megasphaera elsdenii

Ruminal acidosis caused by accumulation of lactic acid, a decrease of pH in the rumen and subsequent imbalance of the rumen fermentation process, affects the health and productivity of dairy cows and beef cattle. Direct-fed microbials have potential for use in the control and prevention of ruminal acidosis. This study investigated the interaction between five strains of dairy propionibacteria, Megasphaera elsdenii and Streptococcus bovis in various co-culture combinations in a simulated rumen environment comprising unmodified rumen digesta supplemented with excess glucose. While suppression of lactic acid accumulation by both the dairy propionibacteria and M. elsdenii in the presence of S. bovis in the simulated rumen conditions was evident, propionibacteria were found to be more effective than M. elsdenii in controlling lactic acid levels.

Silage fermentation and chemical composition of elephant grass inoculated with rumen strains of Streptococcus bovis

The objective of this study was to evaluate the effects of Streptococcus bovis JB1 and HC5 on the fermentation and chemical composition of elephant grass ensiled in laboratory silos. A complete randomized design was used with four treatments: elephant grass silage, elephant grass silage inoculated with 106CFU/g S. bovis JB1 strains; elephant grass silage inoculated with 106CFU/g S. bovis HC5 strains; elephant grass silage inoculated with 106CFU/g Enterococcus faecium, and six replications. The highest number of enterobacteria, fungi and yeast occurred in the control and elephant grass silages inoculated with E. faecium (P<0.05). The silage inoculated with Streptococcus bovis JB1 and HC5 presented the lowest enterobacteria, fungi and yeast populations and the highest number of lactic acid bacteria, 10.03 and 9.97logCFU/g, respectively. The pH and ammoniac nitrogen values were low (P<0.05) in the treatments with Streptococcus bovis JB1 and HC5, respectively. The observed pH values were 3.83 and 3.96 in the treatments with S. bovis JB1 and HC5, respectively, lower than the observed value of 4.01 in the control treatment. The silages inoculated with S. bovis JB1 and HC5 presented the highest (P<0.05) lactic acid values, 67.8 and 66.2g/kg DM, respectively, and the lowest acetic, butyric and propionic acid values. Inoculation with Streptococcus bovis resulted in a higher (P<0.05) crude protein content in the silages, highest dry matter and crude protein recovery and lowest losses through gases and effluents. Treatments with S. bovis JB1 and HC5 presented values of 93.94 and 92.45 for dry matter recovery. There were no statistical differences (P>0.05) for the other chemical characteristics. Both S. bovis JB1 and HC5 improved the fermentation profile, reduced nutrient losses and increased the nutritional value of the elephant grass silage.

Molecular characterization of a novel mosaic tet(S/M) gene encoding tetracycline resistance in foodborne strains of Streptococcus bovis

The presence of antibiotic-resistance (AR) genes in foodborne bacteria of enteric origin represents a relevant threat to human health in the case of opportunistic pathogens, which can reach the human gut through the food chain. Streptococcus bovis is a human opportunistic pathogen often associated with infections in immune-compromised or cancer patients, and it can also be detected in the environment, including fermented foods. We have focused on the molecular characterization of a tetracycline (Tet)-resistance gene present in 39 foodborne isolates of S. bovis phenotypically resistant to this drug. The gene was identified as a novel tet(S/M) fusion, encoding a mosaic protein composed of the N-terminal 33 amino acids of Tet(S), in-frame with the Tet(M) coding sequence. Heterologous expression of the mosaic gene was found to confer Tet resistance upon Escherichia coli recipients. Moreover, the tet(S/M) gene was found to be transcriptionally inducible by Tet under the endogenous tet(S) promoter in both S. bovis and E. coli. Nucleotide sequencing of the surrounding genomic region of 16.2 kb revealed large blocks of homology with the genomes of Streptococcus infantarius and Lactococcus lactis. A subregion of about 4 kb containing mosaic tet(S/M) was flanked by two copies of the IS1216 mobile element. PCR amplification with primers directed outwards from the tet(S/M) gene identified the presence of a 4.3 kb circular form corresponding to the intervening chromosomal region between the two IS1216 elements, but lacking a replication origin. The circular element shared extensive overall homology with a region of the multidrug-resistance plasmid pK214 from Lc. lactis, containing tet(S), as well as the IS1216 transposase-containing element and intervening non-coding sequences. Linear reconstruction of the insertion events likely to have occurred within this genomic region, inferred from sequence homology, provides further evidence of the chromosomal rearrangements that drive genomic evolution in complex bacterial communities such as the gut and food microbiota.

Activity of solvent extracts of Prosopis spicigera, Zingiber officinale and Trachyspermum ammi against multidrug resistant bacterial and fungal strains.

The emerging trends of multidrug resistance among several groups of microorganisms against different classes of antibiotics led different researchers to develop efficient drugs from plant sources to counter multidrug resistant strains. This study investigated different solvent extracts of Prosopis spicigera (P. Spicigera), Zingiber officinale, and Trachyspermum ammi (T. ammi) to determine their efficacy against multidrug resistant microbes. Successive extractions of these plants were performed using a Soxhlet apparatus, using solvents with increasing polarities. Preliminary phytochemical analysis was also performed. Minimum inhibitory concentration was determined by a two-fold serial dilution method followed by determination of minimum bactericidal/fungicidal concentration. Multidrug resistant (MDR) strains of Candida albicans, Candida krusei, Candida tropicalis, Candida glabrata, Escherichia coli and reference strains of Streptococcus mutans and Streptococcus bovis were used in the study. The ethanolic fraction of P. spicigera (least minimum inhibitory concentration [MIC] - 4.88 microg/ml) demonstrated a remarkable inhibition of the microorganisms while fractions obtained from those of Zingiber officinale (least MIC-78.125 microg/ml) exhibited little activity. The petroleum ether fraction of T. ammi (least MIC- 625 microg/ml) showed best activity when compared to its other fractions. Qualitative analysis of the phytoconstituents was also performed. The potency shown by these extracts recommends their use against multidrug resistant microorganisms. This study also showed that P. spicigera could be a potential source of new antimicrobial agents.

The ability of non-bacteriocin producing Streptococcus bovis strains to bind and transfer bovicin HC5 to other sensitive bacteria

Streptococcus bovis HC5 produces a broad spectrum lantibiotic (bovicin HC5), but S. bovis JB1 does not have antimicrobial activity. Preliminary experiments revealed an anomaly. When S. bovis JB1 cells were washed in stationary phase S. bovis HC5 cell-free culture supernatant, the S. bovis JB1 cells were subsequently able to inhibit hyper-ammonia producing ruminal bacteria ( Clostridium sticklandii, Clostridium aminophilum and Peptostreptococcus anaerobius). Other non-bacteriocin producing S. bovis strains also had the ability to bind and transfer semi-purified bovicin HC5. Bovicin HC5 that was bound to S. bovis JB1 was much more resistant to Pronase E than cell-free bovicin HC5, but it could be inactivated if the incubation period was 24 h. Acidic NaCl treatment (100 mM, pH 2.0) liberates half of the bovicin HC5 from S. bovis HC5, but it did not prevent bovicin HC5 from binding to S. bovis JB1. Acidic NaCl liberated some bovicin HC5 from S. bovis JB1, but the decrease in activity was only 2-fold. Bovicin HC5 is a positively charged peptide, and the ability of S. bovis JB1 to bind bovicin HC5 could be inhibited by either calcium or magnesium (100 mM). Acidic NaCl-treated S. bovis JB1 cells were unable to accumulate potassium, but they were still able to bind bovicin HC5 and prevent potassium accumulation by untreated S. bovis JB1 cells. Based on these results, bovicin HC5 bound to S. bovis JB1 cells still acts as a pore-forming lantibiotic.

In vitro bacterial growth and in vivo ruminal microbiota populations associated with bloat in steers grazing wheat forage1

The role of ruminal bacteria in the frothy bloat complex common to cattle grazing winter wheat has not been previously determined. Two experiments, one in vitro and another in vivo, were designed to elucidate the effects of fresh wheat forage on bacterial growth, biofilm complexes, rumen fermentation end products, rumen bacterial diversity, and bloat potential. In Exp. 1, 6 strains of ruminal bacteria (Streptococcus bovis strain 26, Prevotella ruminicola strain 23, Eubacterium ruminantium B1C23, Ruminococcus albus SY3, Fibrobacter succinogenes ssp. S85, and Ruminococcus flavefaciens C94) were used in vitro to determine the effect of soluble plant protein from winter wheat forage on specific bacterial growth rate, biofilm complexes, VFA, and ruminal H2 and CH4 in mono or coculture with Methanobrevibacter smithii. The specific growth rate in plant protein medium containing soluble plant protein (3.27% nitrogen) was measured during a 24-h incubation at 39 degrees C in Hungate tubes under a CO2 gas phase. A monoculture of M. smithii was grown similarly, except under H2:CO2 (1:1), in a basal methanogen growth medium supplemented likewise with soluble plant protein. In Exp. 2, 6 ruminally cannulated steers grazing wheat forage were used to evaluate the influence of bloat on the production of biofilm complexes, ruminal microbial biodiversity patterns, and ruminal fluid protein fractions. In Exp. 1, cultures of R. albus (P < 0.01) and R. flavefaciens (P < 0.05) produced the most H2 among strains and resulted in greater (P < 0.01) CH4 production when cocultured with M. smithii than other coculture combinations. Cultures of S. bovis and E. ruminantium + M. smithii produced the most biofilm mass among strains. In Exp. 2, when diets changed from bermudagrass hay to wheat forage, biofilm production increased (P < 0.01). Biofilm production, concentrations of whole ruminal content (P < 0.01), and cheesecloth filtrate protein fractions (P < 0.05) in the ruminal fluid were greater on d 50 for bloated than for nonbloated steers when grazing wheat forage. The molecular analysis of the 16S rDNA showed that 2 different ruminal microbiota populations developed between bloated and nonbloated animals grazing wheat forage. Bloat in cattle grazing wheat pastures may be caused by increased production of biofilm, resulting from a diet-influenced switch in the rumen bacterial population.

Bacterial competition between a bacteriocin-producing and a bacteriocin-negative strain of Streptococcus bovis in batch and continuous culture

A bacteriocin-producing Streptococcus bovis strain (HC5) outcompeted a sensitive strain (JB1) before it reached stationary phase (pH 6.4), even though it grew 10% slower and cell-free bovicin HC5 could not yet be detected. The success of bacteriocin-negative S. bovis isolates was enhanced by the presence of another sensitive bacterium (Clostridium sticklandii SR). PCR based on repetitive DNA sequences indicated that S. bovis HC5 was not simply transferring bacteriocin genes to S. bovis JB1. When the two S. bovis strains were coinoculated into minimal medium, bacteriocin-negative isolates predominated, and this effect could be explained by the longer lag time (0.5 vs. 1.5 h) of S. bovis HC5. If the glucose concentration of the minimal medium was increased from 2 to 7 mg mL(-1), the effect of lag time was diminished and bacteriocin-producing isolates once again dominated the coculture. When the competition was examined in continuous culture, it became apparent that batch culture inocula were never able to displace a strain that had already reached steady state, even if the inoculum was large. This result indicated that bacterial selection for substrate affinity was even more important than bacteriocin production.

Partial characterization of two ruminal bacteriophages with similar restriction patterns and different capsids morphology

Abstract. Two bacteriophages (F5 and F6) were isolated from lysogenic Streptococcus bovis strains 46/2 and 59/2, respectively, after spontaneous induction. Both bacteriophages produced clear and small plaques (0.1–0.2 mm in diameter) on two host Streptococcus bovis strains (47/3 and 4/1) out of 12 tested. After UV-light induction, clear plaques of 1.0–1.2 mm in diameter were observed. Both bacteriophages were relatively resistant to chloroform, however, their survival in sterilised rumen fluid was not long because their complete inactivation was observed after 18 hours of cultivation in sterilised rumen fluid. Transmission electron microscopy showed great differences in the morphology of particles of these two bacteriophages. The F5 phage had an elongated slightly angular head, of a mean length of 94 nm and width of 50 nm, as well as a 180 nm long and 10–15 nm wide noncontractile flexible tail without a sheath. The bacteriophage F6 had an isometric head of icosahedral shape, 43 nm in diameter, and its noncontractile flexible tail without sheath was about 180–200 nm long and 10–12 nm wide. According to Ackermann's classification both phages belong to Siphoviridae. The genome sizes of both phages, determined by summing the molecular sizes of fragments generated by digestions with EcoRI, PstI, BglII and XbaI, were similar (about 41–43 kb). Restriction analysis of the genomes of these 2 bacteriophages by 8 restriction enzymes showed that SalI, BamHI and BspRI did not cleave the DNAs of these phages. Cleavage of the DNAs with the other five restriction enzymes showed a similar restriction pattern, however, with small differences. It is a curiosity to find two bacteriophages with the same genome size and relatively similar DNA restriction patterns having a different morphology of their capsids.

Geographical difference of disease association in Streptococcus bovis bacteraemia.

From 1996 to 2001, 48 Streptococcus bovis strains were isolated from blood cultures of 37 patients in one hospital. Median patient age was 68 years (range: 1 day-88 years). The male : female ratio was 23 : 14. Most patients (97 %) had underlying diseases, including biliary tract disease in 14 (38 %), diabetes mellitus in 12 (32 %), liver parenchymal disease in seven (19 %), carcinoma of the colon in four (11 %) and other malignancies in four (11 %). No infective foci (indicative of primary bacteraemia) were identified in 15 patients (40 %) and 14 (38 %) had acute cholangitis/cholecystitis, but only four (11 %) had infective endocarditis. Two (5 %), three (8 %) and 32 (87 %) patients had S. bovis of biotypes I, II/1 and II/2, respectively, and three (8 %), two (5 %) and 32 (87 %) patients had S. bovis of genotypes 1, 2a and 2b, respectively. All isolates were sensitive to penicillin, cephalothin and vancomycin, 24 (65 %) were resistant to erythromycin and 15 (41 %) were resistant to clindamycin (these strains were also resistant to erythromycin). Thirteen isolates that were erythromycin- and clindamycin-resistant possessed the ermB gene, 10 possessed the ermT gene and one possessed both the ermB and ermT genes. Overall, seven patients (19 %) died. In contrast to most other reports from western countries, where carcinoma of the colon and infective endocarditis were the major underlying disease and infective focus associated with S. bovis bacteraemia, biliary tract disease and acute cholangitis and/or cholecystitis were the major underlying diseases associated with S. bovis bacteraemia in our locality.

Microbial and physiological characterization of weakly amylolytic but fast-growing lactic acid bacteria: a functional role in supporting microbial diversity in pozol, a Mexican fermented maize beverage.

Pozol is an acid beverage obtained from the natural fermentation of nixtamal (heat- and alkali-treated maize) dough. The concentration of mono- and disaccharides from maize is reduced during nixtamalization, so that starch is the main carbohydrate available for lactic acid fermentation. In order to provide some basis to understand the role of amylolytic lactic acid bacteria (ALAB) in this fermented food, their diversity and physiological characteristics were determined. Forty amylolytic strains were characterized by phenotypic and molecular taxonomic methods. Four different biotypes were distinguished via ribotyping; Streptococcus bovis strains were found to be predominant. Streptococcus macedonicus, Lactococcus lactis, and Enterococcus sulfureus strains were also identified. S. bovis strain 25124 showed extremely low amylase yield relative to biomass (139 U g [cell dry weight](-1)) and specific rate of amylase production (130.7 U g [cell dry weight](-1) h(-1)). In contrast, it showed a high specific growth rate (0.94 h(-1)) and an efficient energy conversion yield to bacterial cell biomass (0.31 g of biomass g of substrate(-1)). These would confer on the strain a competitive advantage and are the possible reasons for its dominance. Transient accumulation of maltooligosaccharides during fermentation could presumably serve as energy sources for nonamylolytic species in pozol fermentation. This would explain the observed diversity and the dominance of nonamylolytic lactic acid bacteria at the end of fermentation. These results are the first step to understanding the importance of ALAB during pozol fermentation.

The antibacterial activity and sensitivity of Streptococcus bovis strains isolated from the rumen of cattle1

Approximately 50% of Streptococcus bovis isolates (n=90) from cattle fed hay- or grain-based diets inhibited the growth of S. bovis JB1. The bacteriocin-like inhibitory substance (BLIS) of the most active strain (HC5) was sensitive to Pronase E, and 16S rDNA analyses indicated that HC5 was closely related to S. bovis strains. When repetitive DNA (BOX) sequences were amplified by PCR, blis+ strains could be organized into 16 BOX-PCR groups, but the similarity indexes were as low as 40%. PCR analyses indicated that none of the blis+ strains had the gene for bovicin 255, a bacteriocin produced by Streptococcus gallolyticus LRC0255, and many of the blis+ isolates were sensitive to bovicin 255. Isolates that survived bovicin 255 and were transferred a second time became less sensitive (≤2 log reduction in viability). The isolates were more sensitive to the BLIS of S. bovis HC5 than bovicin 255, the initial average decrease in viability was approximately 3 logs greater (4.8±2.7 versus 1.8±2.1, respectively, P<0.001), and the HC5-sensitive strains did not adapt. Sixteen of the blis+ isolates were highly resistant to S. bovis HC5 (≤1 log reduction in viability), and BOX-PCR indicated that only five of them had the same BOX pattern as S. bovis HC5. The remaining blis+, HC5-resistant isolates (n=11) had distinctly different BOX patterns and were not always highly resistant to bovicin 255. Because blis+ and blis− strains could be isolated from the same animal, it appears that bacteriocin production is not the only factor affecting S. bovis competition in the rumen.

The antibacterial activity and sensitivity of Streptococcus bovis strains isolated from the rumen of cattle

Approximately 50% of Streptococcus bovis isolates ( n=90) from cattle fed hay- or grain-based diets inhibited the growth of S. bovis JB1. The bacteriocin-like inhibitory substance (BLIS) of the most active strain (HC5) was sensitive to Pronase E, and 16S rDNA analyses indicated that HC5 was closely related to S. bovis strains. When repetitive DNA (BOX) sequences were amplified by PCR, blis + strains could be organized into 16 BOX-PCR groups, but the similarity indexes were as low as 40%. PCR analyses indicated that none of the blis + strains had the gene for bovicin 255, a bacteriocin produced by Streptococcus gallolyticus LRC0255, and many of the blis + isolates were sensitive to bovicin 255. Isolates that survived bovicin 255 and were transferred a second time became less sensitive (≤2 log reduction in viability). The isolates were more sensitive to the BLIS of S. bovis HC5 than bovicin 255, the initial average decrease in viability was approximately 3 logs greater (4.8±2.7 versus 1.8±2.1, respectively, P<0.001), and the HC5-sensitive strains did not adapt. Sixteen of the blis + isolates were highly resistant to S. bovis HC5 (≤1 log reduction in viability), and BOX-PCR indicated that only five of them had the same BOX pattern as S. bovis HC5. The remaining blis +, HC5-resistant isolates ( n=11) had distinctly different BOX patterns and were not always highly resistant to bovicin 255. Because blis + and blis − strains could be isolated from the same animal, it appears that bacteriocin production is not the only factor affecting S. bovis competition in the rumen.

16S ribosomal DNA sequence analysis distinguishes biotypes of Streptococcus bovis: Streptococcus bovis Biotype II/2 is a separate genospecies and the predominant clinical isolate in adult males.

We characterized 22 human clinical strains of Streptococcus bovis by genotypic (16S rRNA gene sequence analysis [MicroSeq]; Applied Biosystems, Foster City, Calif.) and phenotypic (API 20 Strep and Rapid ID32 Strep systems (bioMerieux Vitek, Hazelton, Mo.) methods. The strains, isolated from blood, cerebrospinal fluid (CSF), and urine, formed two distinct 16S ribosomal DNA sequence clusters. Three strains which were associated with endocarditis urinary tract infection (UTI), and sepsis clustered with the S. bovis type strain ATCC 33317 (cluster 1); other closely related type strains were S. equinus and S. infantarius. Nineteen strains clustered at a distance of about 2.5% dissimilarity to the S. bovis type strain (cluster 2) and were associated with central nervous system (CNS) disease in addition to endocarditis, UTI, and sepsis. All strains were distinct from S. gallolyticus. Within cluster 2, a single strain grouped with ATCC strain 43143 (cluster 2a) and may be phenotypically distinct. All the other strains formed a second subgroup (cluster 2b) that was biochemically similar to S. bovis biotype II/2 (mannitol negative and beta galactosidase, alpha galactosidase, beta glucuronidase, and trehalose positive). The API 20 Strep system identified isolates of cluster 2b as S. bovis biotype II/2, those of cluster 1 as S. bovis biotype II/1, and that of cluster 2a as S. bovis biotype I. There was an excellent correlation of biotype and genotype: S. bovis biotype II/2 isolates form a separate genospecies distinct from the S. bovis, S. gallolyticus, and S. infantarius type strains and are the most common isolates in adult males.

The physiological and genetic diversity of bovine Streptococcus bovis strains

Laboratory Streptococcus bovis strains and isolates obtained from a steer fed increasing amounts of grain had similar growth characteristics, but they differed in their sensitivity to 2-deoxyglucose (2DG), a non-metabolizable glucose analog. The addition of 2DG decreased both growth rate (0.92±0.34 h −1) and growth yield (ranging from 25 to 63%), but these differences could not be correlated with diet. However, isolates from a steer fed a 90% grain diet were more prone to 2DG-dependent lysis than those from a hay diet ( P<0.001). All S. bovis laboratory strains and isolates had an identical restriction fragment length polymorphism pattern, when their 16S rDNA was digested with HaeIII and HhaI. However, when genomic BOX elements were amplified, 5–12 bands were observed, and the S. bovis isolates and laboratory strains could be grouped into 13 different BOX types. Strains 26 and 581AXY2 had the same BOX type, but the remaining laboratory strains did not form closely related clusters. Strains JB1 and K27FF4 were most closely related to each other. Most of the fresh isolates (24 out of 30) could be grouped into a single cluster (>90% Dice similarity). This cluster contained isolates from all three diets, but it did not have any of the laboratory strains. The majority (90%) of the isolates obtained from the hay-fed steer exhibited the same BOX type. Because more BOX types were observed if grain was added to the diet, it appears that ruminal S. bovis diversity may be a diet-dependent phenomenon.

The physiological and genetic diversity of bovine Streptococcus bovis strains1

Laboratory Streptococcus bovis strains and isolates obtained from a steer fed increasing amounts of grain had similar growth characteristics, but they differed in their sensitivity to 2-deoxyglucose (2DG), a non-metabolizable glucose analog. The addition of 2DG decreased both growth rate (0.92±0.34 h−1) and growth yield (ranging from 25 to 63%), but these differences could not be correlated with diet. However, isolates from a steer fed a 90% grain diet were more prone to 2DG-dependent lysis than those from a hay diet (P 90% Dice similarity). This cluster contained isolates from all three diets, but it did not have any of the laboratory strains. The majority (90%) of the isolates obtained from the hay-fed steer exhibited the same BOX type. Because more BOX types were observed if grain was added to the diet, it appears that ruminal S. bovis diversity may be a diet-dependent phenomenon.

Identification of bacteriocin-like inhibitors from rumen Streptococcus spp. and isolation and characterization of bovicin 255.

Streptococci obtained from rumen sources were tested for the production of antibacterial compounds using a deferred-antagonism plating assay. Of 35 isolates tested, 7 were identified that inhibited the growth of other streptococci. None of the inhibitory activity was due to bacteriophage. Three isolates, LRC0253, LRC0255, and LRC0476, were selected for further characterization. Analysis of 16S ribosomal DNA indicated that LRC0476 was a strain of Streptococcus bovis, while isolates LRC0253 and LRC0255 are likely strains of Streptococcus gallolyticus. The antibacterial compounds produced by these bacteria were protease sensitive, remained active in a pH range from 1 to 12, and did not lose activity after heating at 100 degrees C for 15 min. The inhibitory peptide from strain LRC0255 was purified using pH-dependent adsorption and desorption to bacterial cells, followed by ammonium sulfate precipitation and reversed-phase chromatography and gel filtration. The peptide was 6 kDa, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. An oligonucleotide probe based on the N-terminal sequence of the purified peptide was used to identify the gene encoding the inhibitory peptide. The antibacterial peptide has characteristics that are very similar to those described for class II bacteriocins of gram-positive bacteria.

Differentiation between Streptococcus gallolyticus Strains of Human Clinical and Veterinary Origins and Streptococcus bovis Strains from the Intestinal Tracts of Ruminants

Differentiation between <i>Streptococcus gallolyticus</i> Strains of Human Clinical and Veterinary Origins and <i>Streptococcus bovis</i> Strains from the Intestinal Tracts of Ruminants

Binding of selected extracellular matrix proteins to enterococci and Streptococcus bovis of animal origin.

Thirty-three enterococcal strains and 10 Streptococcus bovis strains were investigated for their protein-binding cell surface components. Seven extracellular matrix (ECM) proteins were immobilized on Difco latex beads to detect these components on the surface of all enterococcal strains and eight non-autoaggregating S. bovis strains by a particle agglutination assay (PAA). Twenty-three selected strains were also examined in microtiter plate assays. According to the absorbance readings (A(570nm)), 11 strains were classified as nonadherent (A(570nm) < 0.1), 10 strains as weakly adherent (0.1 < A(570nm) > 0.3), and 2 strains as strongly adherent (A(570nm) > 0.3) in these assays. A direct correlation was found between the values obtained in PAA and A(570nm) readings of microtiter plate assays. Binding of (125)I-labeled bovine lactoferrin to enterococci and streptococci was in the range of 6%-30% and of (125)I-labeled human vitronectin in the range of 9%-33% to streptococci. The binding of(125)I-labeled ECM proteins to selected strains was much more effectively inhibited by sulfated carbohydrates than by non-sulfated hyaluronic acid, indicating the importance of the sulfate groups of these inhibitors. An inhibition effect of heparin on bLf binding to four selected strains was higher in comparison with fucoidan in the microtiter plates. Thirty-five out of 44 strains had agglutinated rabbit erythrocytes. However, these strains showed no ability to agglutinate bovine or sheep erythrocytes.

Immunological cross-reactivity between the vaccine and other isolates of Streptococcus bovis and Lactobacillus

Recent studies have showed that immunisation with Streptococcus bovis (Sb-5) and Lactobacillus (LB-27) may confer protection against lactic acidosis in sheep and cattle. The present study was designed to determine the degree of immunological cross-reactivity between Sb-5 and eight other strains of Streptococcus bovis; and between LB-27 and four other isolates of Lactobacillus. The cross-reactivity index (CRI, a low CRI indicates a high degree of immunological cross-reactivity) ranged from 7.3 to 56.1% between the strains of S. bovis (the encapsulated strains with CRIs ranging from 7.3 to 12.4%). For isolates of Lactobacillus the CRIs ranged from 11.5 to 72.2%. The results indicate that all the isolates tested have a certain degree of immunological homology with Sb-5 and LB-27, and suggest that the vaccine may cross-react with a large number of strains of S. bovis and Lactobacillus which may cause lactic acidosis. As most of the S. bovis strains in the rumen are encapsulated, the high degree of homology between Sb-5 and encapsulated S. bovis strains further suggests that the vaccine containing Sb-5 may be effective against a wide range of strains of S. bovis in sheep and cattle.