RESUMO
AIMS: To identify novel actors responsible for the marked adaptation of the Oenococcus oeni species to its environment. METHODS AND RESULTS: Genomic surveillance of the available genome sequences from O. oeni indicated the presence of a small ORF, encoding a protein named Dps(A). The cloned gene complemented the dps(-) mutant of Escherichia coli and conferred resistance to hydrogen peroxide, wine, and metals. The dps(A) gene was flanked by IS-related elements. The entire region was characterized by an anomalously high GC content compared to those reported for oenococcal genomes. The dps(A) gene was present in 15 of the 38 tested isolates. Positive strains originated from different geographical areas and sources. No change in tolerance to wine or to oxidative stress was observed between O. oeni strains harbouring dps(A) and those not harbouring this gene. CONCLUSIONS: Some O. oeni have acquired a functional homologue to the dps gene from E. coli as part of a mobile element. SIGNIFICANCE AND IMPACT OF THE STUDY: Dps(A) probably increases the bacterial fitness in response to environmental challenges. However, the physiological condition under which it adds a selective advantage to O. oeni during winemaking remains to be found.
Assuntos
Proteínas de Bactérias/genética , Genes Bacterianos/genética , Cocos Gram-Positivos/genética , Lactobacillaceae/genética , Adaptação Fisiológica , Proteínas de Bactérias/metabolismo , Genoma Bacteriano , Cocos Gram-Positivos/metabolismo , Lactobacillaceae/metabolismo , Estresse Oxidativo , Reação em Cadeia da PolimeraseRESUMO
Deacidification of grape musts is crucial for the production of well-balanced wines, especially in colder regions of the world. The major acids in wine are tartaric and malic acid. Saccharomyces cerevisiae cannot degrade malic acid efficiently due to the lack of a malate transporter and the low substrate affinity of its malic enzyme. We have introduced efficient pathways for malate degradation in S. cerevisiae by cloning and expressing the Schizosaccharomyces pombe malate permease (mae1) gene with either the S. pombe malic enzyme (mae2) or Lactococcus lactis malolactic (mleS) gene in this yeast. Under aerobic conditions, the recombinant strain expressing the mae1 and mae2 genes efficiently degraded 8 g/L of malate in a glycerol-ethanol medium within 7 days. The recombinant malolactic strain of S. cerevisiae (mae1 and mleS genes) fermented 4.5 g/L of malate in a synthetic grape must within 4 days.
Assuntos
Proteínas de Bactérias , Malatos/metabolismo , Transportadores de Ânions Orgânicos , Saccharomyces cerevisiae/metabolismo , Genes Fúngicos , Hidrólise , Lactococcus lactis/genética , Malato Desidrogenase/genética , Proteínas de Membrana Transportadoras/genética , Proteínas Recombinantes/genética , Saccharomyces cerevisiae/genética , Schizosaccharomyces/enzimologia , Schizosaccharomyces/genéticaRESUMO
Thirty strains of Leuconostoc oenos were exposed to mitomycin C to induce lysogenic bacteriophages. Lysis curves typical for lysogenic strains were obtained with 19 strains. Indicator strans were found for 17 of these phages. Five were characterized by electron microscopy, lytic spectrum, molecular masses of the proteins, sequencing of five N-terminal amino acids of the two major proteins and DNA analysis (restriction patterns, cross hybridization). The results revealed a very close relationship between the phages. Hybridization experiments between the DNAs of the temperate phages and the appropriate lysogenic strains revealed phage-related sequences in the DNA of the lysogenic strain.
Assuntos
Leuconostoc , Lisogenia , Sequência de Aminoácidos , Bacteriófagos/fisiologia , DNA Viral , Lisogenia/efeitos dos fármacos , Mitomicina/farmacologia , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , Proteínas Estruturais Virais/químicaRESUMO
Pediococcus sp. produces an exocellular slime containing exclusively D-glucose. The structure of the polysaccharide was determined by methylation analysis, Smith degradation, enzymic hydrolysis, and 13C-n.m.r. spectroscopy as having a trisaccharide repeating unit, ----3)-beta-D-Glcp-(1---- 3)-[beta-D-Glcp-(1----2)]-beta-D-Glcp-(1----.