Lactococcus garvieae: CHARACTERIZATION AND ABILITY TO INHIBIT THE GROWTH OF AQUACULTURE PATHOGENIC BACTERIA

Abstract

Lactococcus garvieae is a gram-positive ovoid cocci bacterium that was previously included in the genus Lactococcus. The aim of this study was to isolate Lactococcus garvieae from the rearing pond water of catfish. The water is reddish and does not smell fishy and rotten. Lactococcus garvieae was identified and characterized by phenotypic and genotypic observation, analysis of genomic %G~C content, cell surface hydrophobicity assays, acidification test, in vitro antagonism, and antimicrobial activities profile were also performed. The result of molecular identification showed an identity to Lactococcus garvieae with the accession number MT597595.1. Biochemical characterization was performed using API 50 CH kit. The genomics %G~C content of Lactococcus garvieae was 51.8. Based on the acidification test, in vitro antagonism, and bacterial growth in the media with a pH of 4, it is confirmed that Lactococcus garvieae could be able to inhibit Aeromonas hydrophila, Streptococcus agalactiae, Streptococcus iniae, and Edwardsiella ictaluri, except for Edwardsiella tarda. Lactococcus garvieae had the ability to lower the neutral pH of the media to be acidic. The hydrophobic cell surface of Lactococcus garvieae showed an adhesive, hydrophobic, and protein surface cell content that had a compact growth pattern coherent to SAT and MATH positive assay. Antimicrobial activities test using 11 antibiotics showed resistance to Nalidixic acid, and intermediate to Streptomycin and Trimethoprim. Overall, Lactococcus garvieae has the ability to inhibit the growth of pathogenic bacteria, and the potential to produce bacteriocin.