RESUMO
Aims@#Reducing indiscriminate and over use of antibiotics and chemical preservatives, finding better probiotics and new bacteriocins should get paramount importance which will eventually contribute to save lives of newborn to elderly. Some probiotic Lactobacillus produces bacteriocins or bacteriocin-like-substances (BLS) which may be considered as candidates for biopreservatives. The aims of this study was to find probiotic Lactobacillus and assessing their bacteriocinogenic activity. @*Methodology and results@#Five vegetables were processed and isolated 38 Lactic acid bacteria (LAB) by using De Man Rogosa Sharpe (MRS) medium. Among 38 LAB, only 8 (21%) showed potential antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Salmonella Typhii in agar well diffusion method. Finally, we selected two Lactobacillus species such as Lactobacillus plantarum MG1 and L. delbrueckii MT4 for further in vitro testing. Both isolates showed growth capability at wide range of temperatures (27-45 °C), pH (2-9), NaCl (1-7%), bile salt (0.5-2%) and could produce bacteriocin or BLS; which indicated they have potentiality to be probiotic. Bacteriocin or BLS produced by L. plantarum inhibited E. coli and S. Typhii whereas bacteriocin or BLS of L. delbrueckii inhibited S. aureus, E. coli and S. Typhi. These crude bacteriocin or BLS reduced initial bacterial load of vegetables up to 79% after 48 h while 5% of its mixed with vegetables in room temperature. @*Conclusion, significance and impact of study@#The study showed that our isolated L. plantarum and L. delbrueckii could be used as probiotic to improve public health and their bacteriocin or BLS could be used as biopreservatives.
RESUMO
A larga distribuição de Listeria monocytogenes no meio ambiente está provavelmente relacionada com a sua capacidade para sobreviver e se multiplicar sob condições extremas. As novas tendências em termos de conservação de alimentos, incluem a utilização de bioconservantes, embalagens a vácuo e as atmosferas modificadas. O efeito antagónico da nisina em relação a Listeria monocytogenes já está demonstrado, contudo verifica-se que nos alimentos é bastante dependente da composição química do alimento ao qual é adicionada. Também os efeitos da embalagem de alimentos a vácuo e em atmosfera modificada na multiplicação de Listeria monocytogenes são controversos. A utilização de concentrações subletais de agentes de limpeza e desinfecção podem contribuir para o aumento da resistência de Listeria monocytogenes a esse compostos.
The wide distribution of Listeria monocytogenes in the environment is probably related to its ability to survive and grow in extreme conditions. New trends in food preservation include the use of biopreservatives, vacuum packaging and modified atmospheres. The antagonistic effect of nisin on L. monocytogenes has been demonstrated but its activity in foods is strongly dependent on the chemical composition of the food to which is added. Also the effects of vacuum packaging and modified atmosphere packaging on the growth of L. monocytogenes are still controvertial. Sublethal concentrations of cleanning and desinfectants agents can contribute to the and increased resistance of L. monocytogenes to these compounds.