ABSTRACT Aims: This study was aimed to identify the Bacillus spp. strains possessing abilities to inhibit biofilm-forming bacteria and degrade protein and starch. Methodology and results: The ability of bacteria to form biofilms was determined by staining with 1% crystal violet; the biofilm was purple and adhered to the wall of the test tube. The ability to inhibit biofilm-forming bacteria, proteolytic and amylolytic, was determined by bacterial drop and well diffusion methods. The study isolated the STM6 strain capable of creating biofilms and producing H2S gas from shrimp pond slime. Based on the 16S rRNA gene homology and biochemical characterization, the strain was identified as Shewanella putrefaciens. The selected 6 Bacillus strains were capable of inhibiting the growth of STM6 and degrading protein and starch. The strain BTV1 was selected for 16S rRNA gene sequencing and homologous biochemical reactions with Bacillus subtilis. Conclusion, significance and impact of study: Shewanella putrefaciens, which forms biofilm and produces H2S gas from shrimp pond slime, was successfully isolated. The capability of isolated B. subtilis BTV1 for inhibiting S. putrefaciens and degrading organic matter in water was primarily evaluated. Research findings suggest that B. subtilis BTV1 is a potential strain for environmental control in shrimp aquaculture.

Keywords: Amylolytic, Bacillus subtilis, biofilm formation, proteolytic, Shewanella putrefaciens