Characterization of lactic acid bacteria as a fish potential immunostimulant

ABSTRACT

@#Aims: This study aims to characterize the intestinal carp (Cyprinus carpio L.) bacteria, especially lactic acid bacteria (LAB) and its potential as immune-stimulant to be applied in the prevention of diseases in fish. Methodology and result: The bacteria were isolated from carp intestine and cultured in de Mann Rogosa Sharpe (MRS) and glucose yeast peptone agar + calcium carbonate (GYPA+CaCO3) media. The obtained LABs were identified and characterized by 16S rRNA gene primers. The phylogenetic analysis on DNA sequence was performed by using BioEdit and MEGA 7.0 software. The potential immunostimulant were derived from its ability to resist the growth of Aeromonas sp. and Vibrio sp. as pathogenic bacteria by the paper disc agar diffusion method. The clear zone diameter around the paper disc were measured by using calipers. Forty bacteria that isolated from the carp were selected for lactic acid production and clear zone around the colonies were formed from the GYPA+CaCO3. For further analysis, a total of ten LABs were selected based on different colony forms and the largest clear zone around the colonies. Based on phylogenetic analysis, Enterococcus, Lactobacillus, Streptococcus and Lactococcus were found as the genera of lactic acid bacteria. Conclusion, significance, and impact of study We discovered that there is a wide diversity among the 40 isolated bacteria. This result indicates that Enterococcus, Lactobacillus, Streptococcus and Lactococcus were the common genera. The most potential LAB as an immuno-stimulant was Lactobacillus sp.