Evaluation of Antagonism Activity of Potential Malaysian Probiont Strains, Bacillus spp. JAQ04 and Micrococcus spp. JAQ07 in in vitro Condition and on Artemia fransisca against Vibrio alginolyticus
Vibriosis caused by Vibrio alginolyticus has become one of the most threatening diseases that could limit the production of marine fish in aquaculture industry. In this study, microbe strains Micrococcus spp. (JAQ07) and Bacillus spp. (JAQ04) were used as potential probiotics. Both potential probionts were identified as gram-positive bacteria with different morphology. The antagonistic ability of each candidate probiotics towards V. alginolyticus (ATCC33839) were conducted in liquids modes via co-culture assay in three different concentrations of probiont (102, 104 and 106 CFU mL1) and each concentration was inoculated with 105 CFU mL1 of V. alginolyticus. The effectiveness of antagonistic activity was measured by the reduction of V. alginolyticus colonies via plate count at 24 h interval for 120 h. The co-culture assays revealed the reduction of V. alginolyticus colonies by both probiont strains compared to the control (V. alginolyticus at 105 CFU mL1). In in-vivo assay, JAQ04 was able to enhance the survival of Artemia compared to JAQ07 after challenged with V. alginolyticus. Results revealed that at seven days after inoculation, Artemia treated with at 106 CFU mL1 cell density followed by challenged with V. alginolyticus showed 70% of survival, while Artemia challenged with only V. alginolyticus demonstrated a 20% survival rate. Since, both strains displayed excellent probiotic activities, they are indeed suitable probiont candidates for managing Vibriosis infecting marine fish.
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