Microbiologia
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/11840
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Item Bovicin HC5 inhibits wasteful amino acid degradation by mixed ruminal bacteria in vitro(FEMS Microbiology Letters, 2009-03-01) Lima, Janaína R.; Ribon, Andréa de O. Barros; Russell, James B.; Mantovani, Hilário C.Streptococcus bovis HC5 produces a broad spectrum lantibiotic (bovicin HC5) that inhibits pure cultures of hyper ammonia-producing bacteria (HAB). Experiments were preformed to see if: (1) S. bovis HC5 cells could inhibit the deamination of amino acids by mixed ruminal bacteria taken directly from a cow, (2) semi-purified bovicin was as effective as S. bovis HC5 cells, and 3) semi-purified and the feed additive monensin were affecting the same types of ammonia-producing ruminal bacteria. Because purified and semi-purified bovicin HC5 was as effective as S. bovis HC5 cells, it appeared that bovicin HC5 was penetrating the cell membranes of HAB before it could be degraded by peptidases and proteinases. Mixed ruminal bacteria that were successively transferred and enriched nine times with trypticase did not become significantly more resistant to either bovicin HC5 (50 AU mL−1) or monensin (5 μM), and amplified rDNA restriction analysis indicated that bovicin HC5 and monensin appeared to be selecting against the same types of bacteria.Item The effect of carbon and nitrogen sources on bovicin HC5 production by Streptococcus bovis HC5(Journal of Applied Microbiology, 2009-03-23) Carvalho, A.A.T. De; Mantovani, H.C.; Paiva, A.D.; Melo, M.R. DeTo investigate the effect of media composition and agroindustrial residues on bovicin HC5 production by Streptococcus bovis HC5. Batch cultures of S. bovis HC5 were grown in basal medium containing different carbon and nitrogen sources. The activity of cell-free and cell-associated bovicin HC5 was determined in culture supernatants and acidic extracts obtained from cell pellets, respectively. Streptococcus bovis HC5 produced bovicin using a variety of carbon and nitrogen sources. The highest specific activity was obtained in media containing 16 g l−1 of glucose, after 16 h of incubation. The peak in cell-free and cell-associated bovicin HC5 activity was detected when S. bovis HC5 cultures reached stationary phase. The bovicin HC5 specific activity and bacterial cell mass increased approximately 3-fold when yeast extract and trypticase (0·5 and 1·0 g l−1, respectively) were added together to the basal medium. Streptococcus bovis HC5 cultures produced bovicin HC5 in cheese whey and sugar cane juice and maximal volumetric productivity was obtained after 12 h of incubation. Streptococcus bovis HC5 is a versatile lactic acid bacterium that can utilize several carbon and nitrogen sources for bovicin HC5 production. This bacterium could be a useful model to study bacteriocin production in the rumen ecosystem. The use of agroindustrial residues as carbon sources could have an economical impact on bovicin HC5 production. To our knowledge, this is the first report to show the use of sugar cane juice for bacteriocin production by lactic acid bacteria.