In vitro evaluation of probiotic and bacteriocinogenic potentiality of Lactobacillus plantarum and Lactobacillus delbrueckii isolated from vegetables in Chittagong region, Bangladesh

Abstract

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.