RESUMO
Bovine Enterococcus mundtii CRL1656 (Centro de Referencia para Lactobacilos Culture Collection) produces an anti-Listeria and anti-Streptococcus dysgalactiae bacteriocin identified as mundticin CRL1656. The strain and its bacteriocin are candidates to be included in a beneficial product to prevent bovine mastitis as an alternative to antimicrobial agents. To optimize the production of biomass and mundticin CRL1656 by E. mundtii CRL1656, a complete 3 × 2(4) factorial design was applied. The effect of culture medium, initial pH, inoculum size, incubation temperature, and agitation conditions on biomass and bacteriocin production was evaluated simultaneously. Growth parameters were determined using the modified Gompertz model. A nonlinear model was used to estimate the effects of the variables on growth parameters. Bacteriocin production was analyzed using a linear mixed model. Optimal biomass and mundticin CRL1656 production by E. mundtii CRL1656 were obtained in different conditions. Maximal growth was recorded in autolyzed yeast, peptone, tryptone, Tween 80, and glucose or M17 broths, pH 6.5, 5.0% inoculum, 30 °C, with agitation. However, bacteriocin titers were higher in autolyzed yeast, peptone, tryptone, Tween 80, and glucose or de Man-Rogosa-Sharpe (MRS) broths, pH 6.5, 30°C, both with or without agitation. Knowledge of the optimum conditions for growth and bacteriocin production of E. mundtii CRL1656 will allow the obtainment of high levels of biomass and mundticin CRL1656 as bioingredients of potential products to prevent bovine mastitis.
Assuntos
Bacteriocinas/metabolismo , Biomassa , Bovinos/microbiologia , Meios de Cultura/química , Enterococcus/fisiologia , Animais , Bovinos/fisiologia , Feminino , Probióticos/químicaRESUMO
Bovine mastitis produces a wide variety of problems in the dairy farm. The treatment of this disease is based on the use of antibiotics which are not always effective. These drugs are also responsible for the presence of residues in the milk and the increase of antibiotic-resistant strains. Probiotic products were proposed as a valid alternative to antibiotic therapies and are also useful for the prevention of infectious syndromes. With the aim of designing a probiotic product to prevent bovine mastitis, lactic acid bacteria (LAB) were isolated from foremilk samples from different dairy farms in Córdoba-Argentina. One hundred and seventeen LAB were isolated and their beneficial characteristics such as the production of inhibitory substances, surface properties and production of exopolysaccharides (EPS) were assessed. Most of them displayed low degree of hydrophobicity, autoaggregation, EPS negative phenotype and were identified as Enterococcus hirae and Pediococcus pentosaceus. Nine LAB strains inhibited three indicator bacteria. Some isolates were pre-selected and genetically identified according to the results obtained. Antibiotic resistance and virulence factors were studied for the assessment of the safety of the strains. The results obtained were compared to those reported previously from samples obtained in the North-western area of the country and some differences were found.
Assuntos
Lactobacillaceae/isolamento & purificação , Lactobacillaceae/fisiologia , Mastite Bovina/prevenção & controle , Leite/microbiologia , Animais , Antibacterianos/farmacologia , Antibiose , Bovinos , Farmacorresistência Bacteriana , Feminino , Lactobacillaceae/efeitos dos fármacos , Metaboloma , Metagenoma , Testes de Sensibilidade Microbiana , Polissacarídeos Bacterianos/biossíntese , Fatores de VirulênciaRESUMO
Probiotics are frequently used for multiple objectives and the majority of applications are performed both in human beings and in different animals. The specificity of species showed by the members of the indigenous microbiotia led us to isolate lactic acid bacteria (LAB) from their natural bovine ecosystems and to select those with probiotic potentiality. The beneficial probiotic LAB were isolated from the vaginal tract and mammary gland of adult heifers, faeces and oral cavity of newborn calves. Bacterial strains and their numbers varied in each tract under study. Their surface properties, evaluated using the MATH test, revealed that the higher number of low hydrophobic strains were isolated from vaginal tract, mammary gland or faeces. The capability of autoaggregation also differed with higher degree in those isolated from vagina, whereas those that originated in the mammary gland or faeces showed low autoaggregation characteristics. The production of antagonistic substances showed that the production of hydrogen peroxide was higher in the strains isolated from the vaginal tract, while those able to produce organic acid were isolated from all the environments. A few strains were able to produce bacteriocins and were isolated only from the mammary gland and faeces, but not from the vaginal tract. Further studies are being performed to complete the functional characterization of the strains in order to evaluate their survival in the environmental conditions of each tract. Finally, the selected strains could be combined for the design of probiotic products to be used both in adult cows and in neonates, based on the host-specificity, due to their autochthonous origin and their potential use in the tract where they were isolated.