Antibacterial activity of shrimp chitosan against Escherichia coli, Salmonella, and Pseudomonas aeruginosa isolated from seafoods

Abstract

Antibacterial activity of shrimp shell based chitosan was determined against three food borne pathogens viz., Escherichia coli, Salmonella, and Pseudomonas aeruginosa isolated from seafoods. Tests were carried out in phosphate buffered saline (PBS) at pH 6.0. Four different concentrations, 0.01%, 0.03%, 0.05% and 0.1% (w/v) of chitosan were used against E.coli and Salmonella, and 0.01%, 0.05%, 0.5% and 1% were against P. aeruginosa. Chitosan showed stronger bactericidal activity against Salmonella compared to E.coli and P. aeruginosa as evidenced by 3 log cfu. ml super(-1) reduction in Salmonella count with 0.01% chitosan concentration. There was complete elimination of 5 log cfu. ml super(-1) cell count of Salmonella within 24 h at 0.1% chitosan level. There was 3 log reduction in E.coli count at 0.01% chitosan, but not completely inhibited even at the maximum used concentration (0.1%). The inhibition concentration against P. aeruginosa was higher level compared to Enterobacteriaceae and it was found that reduction in 5 log cfu. ml super(-1) was achieved only at 72 h of chitosan exposure. Different chitosan concentrations 0.05%, 0.1% and 1% had almost same inhibition pattern for P. aeruginosa at 6h. 18h 36h and 72h of exposure. The effectiveness of chitosan against tested pathogens showed Salmonella was most susceptible towards chitosan followed by E.coli and P. aeruginosa.