Bioquímica e Biologia Molecular
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/11837
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Item Strategies to select yeast starters cultures for production of flavor compounds in cachaça fermentations(Antonie van Leeuwenhoek, 2011-09-20) Souza, Anderson Proust Gonçalves de; Vicente, Maristela de Araújo; Klein, Raphael Contelli; Fietto, Luciano Gomes; Coutrim, Maurício Xavier; Afonso, Robson José de Cássia Franco; Araújo, Leandro Dias; Silva, Paulo Henrique Alves da; Bouillet, Leoneide Érica Maduro; Castro, Ieso Miranda; Brandão, Rogelio LopesIn this work, we have used classical genetics techniques to find improved starter strains to produce cachaça with superior sensorial quality. Our strategy included the selection of yeast strains resistant to 5,5′,5″-trifluor-d,l-leucine (TLF) and cerulenin, since these strains produce higher levels of higher alcohols and esters than parental strains. However, no clear relationship was observed when levels of flavoring compounds were compared with the levels expression of the genes (BAT1, BAT2, ATF2, EEB1 genes) involved with the biosynthesis of flavoring compounds. Furthermore, we determined the stability of phenotypes considered as the best indicators of the quality of the cachaça for a parental strain and its segregants. By applying the principal component analysis, a cluster of segregants, showing a high number of characteristics similar to the parental strain, was recognized. One segregant, that was resistant to TLF and cerulenin, also showed growth stability after six consecutive replications on plates containing high concentrations of sugar and ethanol. “Cachaça” produced at laboratory scale using a parental strain and this segregant showed a higher level of flavoring compounds. Both strains predominated in an open fermentative process through seven cycles, as was shown by mitochondrial restriction fragment length polymorphisms analysis. Based on the physical chemical composition of the obtained products, the results demonstrate the usefulness of the developed strategies for the selection of yeast strains to be used as starters in “cachaça” production.Item Draft genome sequences of Staphylococcus aureus strains isolated from subclinical bovine mastitis in Brazil(Genome Announcements, 2016-02-18) Silva, Danielle Mendes; Silva, Mônica Pacheco da; Vidigal, Pedro M. Pereira; Barcelos, Rafael Mazioli; Klein, Raphael Contelli; Aguilar, Ananda Pereira; Fabres-Klein, Mary Hellen; Oliveira, Guilherme; Ribon, Andréa Oliveira BarrosHere, we present the draft genome sequences of four Staphylococcus aureus strains isolated from mastitic milk collected from animals with subclinical manifestations. Three of them were typed as sequence type 126 (ST126), a genotype with no genome sequence available. ST126 is found in several herds of southern Brazil and is described as a bovine pathogen strongly associated with milk around the world.Item An association between milk and slime increases biofilm production by bovine Staphylococcus aureus(Biomed Central Public Veterinary Research, 2015-01-16) Fabres-Klein, Mary Hellen; Santos, Mário Junior Caizer; Klein, Raphael Contelli; Souza, Guilherme Nunes de; Ribon, Andrea de Oliveira BarrosStaphylococcus aureus is associated with chronic mastitis in cattle, and disease manifestation is usually refractory to antibiotic therapy. Biofilm production is a key element of S. aureus pathogenesis and may contribute to the treatment failure that is consistently reported by veterinarians. Minas Gerais State is the largest milk-producing state in Brazil, and the characterization of bacterial isolates is an important aspect of disease control for dairy farmers. Here, we investigated the potential of S. aureus isolated from bovine mastitis to produce slime and biofilm in a skim-milk medium and classified the isolates according to their agr type.Item A C-Type Lectin from Bothrops jararacussu Venom disrupts staphylococcal biofilms(Plos One, 2015-03-26) Klein, Raphael Contelli; Fabres-Klein, Mary Hellen; Oliveira, Leandro Licursi de; Feio, Renato Neves; Malouin, François; Ribo, Andréa de Oliveira BarrosBovine mastitis is a major threat to animal health and the dairy industry. Staphylococcus aureus is a contagious pathogen that is usually associated with persistent intramammary infections, and biofilm formation is a relevant aspect of the outcome of these infections. Several biological activities have been described for snake venoms, which led us to screen secretions of Bothrops jararacussu for antibiofilm activity against S. aureus NRS155. Crude venom was fractionated by size-exclusion chromatography, and the fractions were tested against S. aureus. Biofilm growth, but not bacterial growth, was affected by several fractions. Two fractions (15 and 16) showed the best activities and were also assayed against S. epidermidis NRS101. Fraction 15 was identified by TripleTOF mass spectrometry as a galactose-binding C-type lectin with a molecular weight of 15 kDa. The lectin was purified from the crude venom by D-galactose affinity chromatography, and only one peak was observed. This pure lectin was able to inhibit 75% and 80% of S. aureus and S. epidermidis biofilms, respectively, without affecting bacterial cell viability. The lectin also exhibited a dose-dependent inhibitory effect on both bacterial biofilms. The antibiofilm activity was confirmed using scanning electron microscopy. A pre-formed S. epidermidis biofilm was significantly disrupted by the C-type lectin in a time-dependent manner. Additionally, the lectin demonstrated the ability to inhibit biofilm formation by several mastitis pathogens, including different field strains of S. aureus, S. hyicus, S. chromogenes, Streptococcus agalactiae, and Escherichia coli. These findings reveal a new activity for C-type lectins. Studies are underway to evaluate the biological activity of these lectins in a mouse mastitis model.