Characterization of chitinolytic bacteria isolated from shrimp and crab waste producing chitinase and anti-fungal enzymes to overcome saprolegniasis in aquaculture

Abstract

Chitinolytic bacteria was proposed in this study as an effective solution to overcome the growth of Saprolegnia sp in aquaculture practices.Saprolegnia sp. causesSaprolegniosis, a disease that affects aquaculture species characterised by white filamentous mycelium on the body or fins of freshwater fish. The use of probiotic bacteria as an alternative strategy to traditional chemical remedies may be applied. Potential bacteria may be isolated from shrimp and crab waste since these organic materials were known to harbor these organisms. The search for the specific bacteria was conducted through the research activity namely isolation and cultivation of bacteria, chitinolytic activity test, anti-fungal activity test using Saprolegnia sp and finally characterization through molecular analysis of 16S rRNA gene and chitinase encoding fragments. Cultivation of isolated bacteria and general characterization used Gram staining while the results of the chitinolytic activity test showed that the selected candidates (species 1 dan 2) obtained the highest chitinolytic indexes of 2.12 mm and 1.99 mm, respectively. Results of the invitroanti-fungal activity test usingSaprolegnia sp using species 1 and 2 obtained the zone of inhibitionrespectively 6.00 mm and11.59 mm. Species 1 and 2 were identified with a similiarity of 96% to Bacillus thuringiensis (no accession YP 003665928.1) and 99% identical toBacillus cereus (without accession WP 000932552.1).