Screening of antibacterial activity of mucus extract of snakehead fish, Channa striatus (Bloch).

AIM The objective of this study is to gain a better understanding of the antimicrobial properties of the mucus extract of snakehead fish, Channa striatus against selected human and fish pathogenic microbes. MATERIALS AND METHODS The fish mucus samples were extracted with crude, acidic and aqueous solvents to identify potential antimicrobial agents including aqueous and acid soluble compounds. The study also determined the protein content of the three different mucus extracts. The highest protein content (0.589 mg/ml) was noticed in the crude extract followed by aqueous mucus extract (0.291 mg/ml) and acidic extract (0.267 mg/ml). Preliminary screening for antimicrobial activity of all three mucus extracts were tested against 5 human pathogens (Bacillus subtilis, Klebsiella pneumoniae, Salmonella enteritidis, Proteus vulgaris and Pseudomonas aeruginosa) and fish pathogen (Aeromonas hydrophila) using the British Society for Antimicrobial Chemotherapy (BSAC) standardized disc susceptibility test method. The activity was measured in terms of zone of inhibition in mm. RESULTS The acidic mucus extracts exhibited a bactericidal activity and inhibited the growth of Klebsiella pneumoniae, Pseudomonas aeruginosa and Bacillus subtilis while aqueous and crude extract showed no bactericidal activity for any of the human pathogens tested. Further test against fish pathogen Aeromonas hydrophila showed that the aqueous and crude extracts are capable of inhibiting the growth of the pathogen, demonstrating the presence of antimicrobial agents and the role of fish mucus in antimicrobial protection. CONCLUSIONS The present results suggest that the mucus extracts of snakehead fish Channa striatus may be a potential source of antimicrobial agents for human and fish pathogens.