Microbiologia
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/11840
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Item Distribution and genetic diversity of bacteriocin gene clusters in rumen microbial genomes(Applied and Environmental Microbiology, 2015-08-02) Azevedo, Analice C.; Bento, Cláudia B. P.; Ruiz, Jeronimo C.; Queiroz, Marisa V.; Mantovani, Hilário C.Some species of ruminal bacteria are known to produce antimicrobial peptides, but the screening procedures have mostly been based on in vitro assays using standardized methods. Recent sequencing efforts have made available the genome sequences of hundreds of ruminal microorganisms. In this work, we performed genome mining of the complete and partial genome sequences of 224 ruminal bacteria and 5 ruminal archaea to determine the distribution and diversity of bacteriocin gene clusters. A total of 46 bacteriocin gene clusters were identified in 33 strains of ruminal bacteria. Twenty gene clusters were related to lanthipeptide biosynthesis, while 11 gene clusters were associated with sactipeptide production, 7 gene clusters were associated with class II bacteriocin production, and 8 gene clusters were associated with class III bacteriocin production. The frequency of strains whose genomes encode putative antimicrobial peptide precursors was 14.4%. Clusters related to the production of sactipeptides were identified for the first time among ruminal bacteria. BLAST analysis indicated that the majority of the gene clusters (88%) encoding putative lanthipeptides contained all the essential genes required for lanthipeptide biosynthesis. Most strains of Streptococcus (66.6%) harbored complete lanthipeptide gene clusters, in addition to an open reading frame encoding a putative class II bacteriocin. Albusin B-like proteins were found in 100% of the Ruminococcus albus strains screened in this study. The in silico analysis provided evidence of novel biosynthetic gene clusters in bacterial species not previously related to bacteriocin production, suggesting that the rumen microbiota represents an underexplored source of antimicrobial peptides.Item New Lager Brewery Strains obtained by crossing techniques using cachaça (Brazilian Spirit) yeasts(Applied and Environmental Microbiology, 2017-08-04) Queiroz, Marisa Vieira de; Figueiredo, Bruna Inez Carvalho; Saraiva, Margarete Alice Fontes; Pimenta, Paloma Patrick de Souza; Testasicca, Miriam Conceição de Souza; Sampaio, Geraldo Magela Santos; Cunha, Aureliano Claret da; Afonso, Luis Carlos Crocco; Castro, Ieso de Miranda; Brandão, Rogelio LopesThe development of hybrids has been an effective approach to generate novel yeast strains with optimal technological profile for use in beer production. This study describes the generation of a new yeast strain for lager beer production by direct mating between two Saccharomyces cerevisiae strains isolated from cachaça distilleries: one that was strongly flocculent, and the other with higher production of acetate esters. The first step in this procedure was to analyze the sporulation ability and reproductive cycle of strains belonging to a specific collection of yeasts isolated from cachaça fermen- tation vats. Most strains showed high rates of sporulation, spore viability, and homothal- lic behavior. In order to obtain new yeast strains with desirable properties useful for la- ger beer production, we compare haploid-to-haploid and diploid-to-diploid mating procedures. Moreover, an assessment of parental phenotype traits showed that the seg- regant diploid C2-1d generated from a diploid-to-diploid mating experiment showed good fermentation performance at low temperature, high flocculation capacity, and de- sirable production of acetate esters that was significantly better than that of one type la- ger strain. Therefore, strain C2-1d might be an important candidate for the production of lager beer, with distinct fruit traces and originating using a non-genetically modified organism (GMO) approach. Recent work has suggested the utilization of hybridization techniques for the generation of novel non-genetically modified brewing yeast strains with combined properties not commonly found in a unique yeast strain. We have observed remarkable traits, especially low temperature tolerance, maltotriose utilization, flocculation ability, and production of volatile aroma compounds, among a collection of Saccharomyces cerevisiae strains isolated from cachaça distilleries, which allow their utilization in the production of beer. The significance of our research is in the use of breeding/hybridization techniques to generate yeast strains that would be appropriate for producing new lager beers by exploring the capacity of cachaça yeast strains to flocculate and to ferment maltose at low temperature, with the concomitant production of flavoring compounds.Item Role of lipid II and membrane thickness in the mechanism of action of the lantibiotic bovicin HC5(Antimicrobial Agents and Chemotherapy, 2011-08-19) Paiva, Aline Dias; Breukink, Eefjan; Mantovani, Hilário CuquettoLantibiotics are antimicrobial peptides produced by Gram-positive bacteria, nisin being the most well known member. Nisin inhibits peptidoglycan synthesis and forms pores at sensitive membranes upon interaction with lipid II, the essential bacterial cell wall precursor. Bovicin HC5, a bacteriocin produced by Streptococcus bovis HC5, has the putative N-terminal lipid II binding motif, and we investigated the mode of action of bovicin HC5 using both living bacteria and model membranes, with special emphasis on the role of lipid II. Bovicin HC5 showed activity against Staphylococcus cohnii and Staphylococcus warneri, but bovicin HC5 hardly interfered with the membrane potential of S. cohnii. In model membranes, bovicin HC5 was not able to cause carboxyfluorescein release or proton influx from DOPC vesicles containing lipid II. Bovicin HC5 blocked lipid II-dependent pore formation activity of nisin, and a high-affinity interaction with lipid II was observed (apparent binding constant [K a ] ⴝ 3.1 ⴛ 10 6 M ⴚ1 ), with a 1:1 stoichiometry. In DOPC vesicles containing lipid II, bovicin HC5 was able to assemble with lipid II into a prepore-like structure. Furthermore, we observed pore formation activity of bovicin HC5, which was stimulated by the presence of lipid II, in thin membranes. Moreover, bovicin HC5 induced the segregation of lipid II into domains in giant model membrane vesicles. In conclusion, bovicin HC5 has a primary mode of action similar to that of nisin, but some differences regarding the pore-forming capacity were demonstrated.