Infection of marine fish by pathogens such as Vibrio spp. are a common consequence in intensive aquaculture due to poor management practice. Mass mortalities translates to severe economic losses for farmers. Antibiotics used to combat disease outbreak encourages the proliferation of antibiotic-resistance among bacteria populations. Probiotics in aquaculture have been gaining traction as an alternative environmentally friendly tool for disease control. Hence, this study aims to develop and evaluate a multi-strain bacterial consortium as potential probiotics against vibriosis.
Isolated probiotic strains were screened for antagonistic activities against Vibrio alginolyticus, and its probiotic properties. Lysinibacillus fusiformis SPS11, Bacillus megaterium I24 and Bacillius sp. A2 displayed inhibition against V. alginolyticus and were selected and mixed as multi-strain probiotics. In biofilm formation assay, multi-strain probiotics showed significantly higher formation (1.312±0.101) at 12-hour compared with V. alginolyticus only (0.516±0.069). Preliminary in-vivo challenge assay using Artemia revealed that Artemia treated with 108 CFUmL-1 multi-strain mix and challenged with 106 CFUmL-1 V. alginolyticus (76.67±1.67%) demonstrated highest survival. It also had significantly higher survival when compared to Artemia treated with 106 CFUmL-1 probiotic mix (65.00±0.00%) challenged with 106 CFUmL-1 V. alginolyticus. Vibrios count showed negative reduction in V. alginolyticus in Artemia treated with 106 CFUmL-1 multi-strain mix but positive and significant reduction in Artemia treated with 108 CFUmL-1. There was a slight reduction in vibrios count in culture water across all treatments with 106 CFUmL-1 and 108 CFUmL-1 of multi-strain mix. Therefore, this study highlights the potential of the formulated probiotic mix as potential probiotics against vibriosis in the aquaculture industry.