Purification and characterisation of a novel bacteriocin produced by Enterococcus faecalis from the indigenous North East fermented food aakhone

Abstract

Aakohone, a traditional Manipuri fermented dish made from sticky fermented soybeans, possesses unique clinically beneficial properties. Since these fermented foods have been consumed for generations, bacterial cultures isolated from them are unlikely to be perceived as foreign by the human immune system when used as probiotics. In this study, a bacteriocin-producing Enterococcus faecalis strain was isolated from aakhone. The culture-free supernatant was collected, precipitated and dialyzed. The antibacterial activity of the supernatant and dialyzed sample was tested against Listeria monocytogenes, Escherichia coli and Streptococcus mutans. Various physiological properties, including growth patterns, bacteriocin production and sensitivity to different enzymes, cholesterol reduction test, acid tolerance and biofilm activity were all studied, as well as the effects of temperature, pH and salinity. Using Lowry's method, the cell wall protein was isolated from the strain and quantified. Silver staining was used to identify the low molecular weight protein bands and to analyse their molecular weight. To purify the sample, column chromatography was used. After being lyophilized, the three fractions exhibiting antibacterial activity were applied to SDS-PAGE. According to the current study, E. faecalis from aakhone is a promising strain for future probiotic research.