Isolation and Molecular Identification of Termite Nest Associated Bacteria with Potential as Vibriosis Biocontrol Agents in Shrimp Farming

Abstract

The potential for aquaculture development in Indonesia, especially the shrimp farming industry, is projected to continue to increase. However, the current growth in aquaculture production is in line with the increasing number of disease outbreaks and can affect the production, profitability, and sustainability of the industry worldwide. Vibriosis is a major challenge in aquaculture that causes fish mortality in large numbers and rapid times. Vibriosis treatment is still limited to the same antibiotics in humans and animals. For this reason, alternative microorganisms that are more specific and selective in inhibiting vibrio are needed, one of which is the exploration of termite nest association bacteria. This study aims to obtain isolates of termite nest association bacteria that are antivibrio. Isolation of bacteria using ISP2 media. Furthermore, antagonistic screening was carried out against V. alginolyticus and V. harveyi bacteria. Isolates performed morphological and biochemical characterization followed by molecular identification with 16s rRNA sequence analysis using universal primer 27F 1492R. Isolation results obtained 15 isolates with varying colors and shapes. Ten isolates are Gram-positive bacteria and 12 isolates have a positive catalase test. Seven isolates have antivibrio activity, namely isolates SR9, SE1, SE4, SE5, SE6, SE7 and SE8. Isolate SE1 showed the best antivibrio activity capable of inhibiting the growth of V. alginolyticus and V. harveyi bacteria with an inhibition zone value of 3.5 cm and 4 cm, respectively. The results of the molecular analysis showed that isolate SE1 has 99.65% similarity with Bacillus amyloliquefaciens strain HY2-1. These bacteria have characteristics that have the potential to be used as probiotics in the aquaculture industry, especially vibrio biocontrol agents.