Selection of potential lactic acid bacteria from fish intestine of mackerel (Rastrelliger kanagurta) from Lembata Regency, East Nusa Tenggara, Indonesia

ABSTRACT

Aims@#The aim of this study was to screen lactic acid bacteria (LAB) isolates with probiotic properties for tilapia (Oreochromis niloticus) from the intestines of mackerel and to analyze its ability to produce hydrolase enzymes (amylase, protease, cellulase and lipase).@*Methodology and results@#Ten samples of mackerel were collected from the Fish Auction Place, Lewoleba, Nubatukan District, Lembata Regency, East Nusa Tenggara Province, Indonesia. The process for screening were antimicrobial activity, pH tolerance test of 1, 3 and 5, bile salt concentrations of 2.5%, 5% and 7.5%, and water salinity (0.5%, 3.5% and 6.5%). The autoaggregation and semi-qualitative test of hydrolase enzymes were also carried out. In total, 21 LAB isolates were derived from mackerel intestines. Isolates that have the stronger ability to inhibit the pathogen Aeromonas hydrophila ATCC 7966 are KBP 3.3, KBP 3.3.1 and KBP 6.3, while KBP 1.3, KBP 1.1.1 and KBP 3.3.1 were able to inhibit Streptococcus agalactiae ATCC 13813. The LAB isolates that survived at the tested pH were KBP 3.3.1, KBP 3.3, KBP 1.1.1 and KBP 1.3. Results also suggest that the four isolates were tolerant to bile salt concentrations and water salinity with good survival rates (>94.7%) and had proteolytic, lipolytic and cellulolytic activities. The isolates KBP 3.3, KBP 3.3.1 and KBP 1.1.1 were identified as Weissella confusa 6250, while the isolate KBP 1.3 was identified as W. confusa C5-7.@*Conclusion, significance and impact of study@#The characteristics of four selected isolates indicate their potential as a probiotic. These potential probiotic isolates can be applied directly to fish by utilizing microencapsulation technology or adding to the feed.