Characterization and in-vitro screening of probiotic potential of novel Weissella confusa strain GCC_19R1 isolated from fermented sour rice

Abstract

Fermented sour rice is a unique traditional sour food of Indian subcontinent, particularly in the eastern and north-eastern part of India, which according to traditional belief, may have therapeutic and prophylactic applications against various disorders. The study aims to characterize the potential fermentative-bacteria from traditional sour rice, followed by in-vitro assessment for safety and security for human consumption. Fermented sour rice samples were collected from 23 households of Cachar district of Assam, India, which was prepared by soaking the cooked rice in water for an overnight period of 12–16 h. Isolation and enumeration of bacteria from fermented sour rice samples was carried on MRS agar plates. The isolates were identified by biochemical tests and 16S rDNA sequencing. In-vitro tests were performed to assess the probiotic properties, colonization properties, haemolytic activity and antagonistic activity against other pathogens. The predominant fermentative-bacteria was identified as Weissella confusa strain GCC_19R1 (GenBank: MN394112). The isolate showed significant growth in the presence of artificial gastric-juice, bile and pancreatin. A moderate percentage of hydrophobicity (35.8% for n-hexadecane and 32.56% for toluene) and autoaggregation (38.7%) was also recorded. The strain survived well at acidic pH, 12.5% NaCl, and able to ferment glucose, arabinose and sucrose. The strain fulfilled the safety criteria concerning haemolytic activity, inhibits the growth of other bacteria, and found to be resistant towards antibiotics that are commonly used for GI-tract infections. From the gathered data, it could be concluded that the novel strain of W. confusa is responsible for rice fermentation. The strain can be used as a starter culture for the production of sour rice. Further in-vivo studies are needed to better explicate their safety aspects, nutritional parameters and health benefits.