Streptomyces sp. Vitnk9 Derived Compound against Fish Bacterial Pathogens

Background: The extensive research in the field of aquaculture is essential to combat the fish bacterial diseases causing massive economic loss to the aquaculture industry and these pathogens remains to be a threat to human well-being due to consumption of fish and fish products as a major food source. Methods: This study focuses on extraction and identification of the antibacterial compound produced by Streptomyces sp. VITNK9 against selected fish bacterial pathogens. Results: Bioactivity-guided extraction of ethyl acetate extract and purification results in isolation of the lead compound 1-(2-hydroperoxycyclopentyl)-4-hydroxytridecan-7-one (HCHD) from Streptomyces sp. VITNK9 having a chemical formula of C18H34O4 and a molecular weight of 314.46 g/mol. HCHD (100 μg/ml) demonstrated antibacterial activity with the inhibition zone of 19.33 ± 0.47 mm and the MIC (minimal inhibitory concentration) of 3.125 μg/ml toward Edwardsiella tarda and 16.66 ± 0.47 mm and the MIC value of 12.5 μg/ml against Aeromonas hydrophila. In silico molecular docking studies showed the interaction of HCHD with the drug target enzyme acetate kinase of E. tarda and A. hydrophila. It showed the least binding free energy of-6.5Kcal/mol and-6.1 Kcal/mol with acetate kinase of E. tarda and A. hydrophila, respectively. Conclusion: The outcome of this study suggests that the inhibition of bacterial acetate kinase by the lead compound HCHD and thereby affects the bacterial metabolism. Streptomyces species are more promising source for isolating antibacterial secondary metabolites for controlling fish bacterial pathogens.