Probiotic lactic acid bacteria from papaya, banana fruits and fermented red raw rice batter: isolation, screening and antimicrobial property

Abstract

Probiotic lactic acid bacteria are “live microorganisms which, when administered in adequate amounts, confer a health benefit on the host”. Therefore, the purpose of the study was to isolate the lactic acid bacteria from papaya fruit, banana fruits, fermented papaya fruit, fermented banana fruit and fermented red raw rice batter to screen the probiotic potential of isolated strains. The gram staining and catalase tests were performed to identify the presumptive lactic acid bacteria. Further, the isolated strains were subjected to diverse biochemical and physiological tests, such as different carbohydrate fermentation test, gas production from fructose and glucose and ability to survive under different temperature, pH concentration, bile salt concentration and sodium chloride concentration. The antimicrobial test was done for all selected isolated bacterial strains against E. coli, Pseudomonas aeruginosa and Staphylococcus aureus. Eight bacterial strains were isolated, and all isolated bacteria strains were gram positive, catalase negative, non-spore forming and non-motility strains. Based on the antimicrobial activity, the R2 isolated from fermented red raw rice batter and FB1 and FB2 isolated from fermented banana fruit bacterial strains have ability to control E. coli, Pseudomonas aeruginosa and Staphylococcus aureus than other bacterial strains. Therefore, the R2, FB1 and FB2 bacterial strains identified as probiotic lactic bacterial strains due to antimicrobial activity. Based on the biochemical and physiological tests indicated that R2 can survive at low pH (1.5 to 4), high temperature (470C), different bile salt concentrations (0.3%, 0.8% and 1.0%) and different sodium chloride concentrations (2% ,6% and 10%). Therefore, this study concluded that R2 isolated from fermented red raw rice batter considered as potential probiotic lactic acid bacteria. Further study could be performed to confirm its probiotic potential and identify strain based on molecular techniques.