Isolation and characterization of Lactococcus garvieae from the fish gut for in vitro fermentation with carbohydrates from agro-industrial waste

Abstract

This study focused on agro-industrial waste such as fruit peels by extracting prebiotics as a carbon source for lactic acid bacteria (LAB). Four strains of LAB were selected from <i>Oreochromis niloticus</i> (B2 and B3) and <i>Nemipterus japonicas</i> (R4 and R5), and identified as <i>Lactococcus garvieae</i> through 16S rRNA gene sequencing. The analysis of probiotic characteristics revealed that all four strains were able to tolerate sodium chloride (up to 7 %), bile salt (up to 3 %), and broad range of pH (2-9). Further, analysis of polysaccharide contents in the agro-industrial waste materials such as peels of pineapple, orange, lemon, sugarcane, pomegranate, and sweet lemon revealed that the concentration ranged from 3.91-163.85 mg/g. It was observed that orange peels (20.38-140.99 mg/g), sweet lemon peels (22.03-161.93 mg/g), and pomegranate peels (38.19-163.85 mg/g) yielded maximum indigestible polysaccharide. Evaluation of synbiotic combination of probiotic and prebiotic revealed that <i>L. garvieae</i> strains had better fermentation efficiency with orange, sweet lemon, and pineapple compared to lemon, sugarcane, and pomegranate. In nutshell, different types of agro-industrial waste evaluated in this research were found to be a cheap and fermentable carbon sources for LAB. Further study should be conducted to analyze this symbiotic combination as feed supplements for fish in aquaculture as well as various fermentation industries.