Physicochemical Properties of Chitosan Extracted from Pleurotus ostreatus and Improvement of its Antibacterial Activity by Gamma Radiation

Abstract

This study was carried out to determine the physicochemical characteristics such as intrinsic viscosity (IV), molecular weight (MW), water binding capacity (WBC), and fat binding capacity (FBC) of chitosan extracted Pleurotus ostreatus fruit body. Antibacterial activity of the gamma irradiated chitosan was also determined. The intrinsic viscosity, MW, WBC and FBC of the produced chitosan were 769.69 ml/g, 1.8×105 Da, 408% and 234%, respectively. The fungal chitosan was subjected to different doses (viz., 5, 10, 20, 30 and 40 kGy) of radiation from 60Co gamma source to observe the effect of gamma radiation on its antibacterial activity. After irradiation, antibacterial activity was evaluated and compared with that of non-irradiated chitosan. Non-irradiated chitosan showed moderate antibacterial activity against Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 35150, and Salmonella enteritidis ATCC 13076 whereas chitosan samples treated with 5, 10 and 20 kGy gamma irradiation separately have shown enhanced antibacterial activity than that of non-irradiated chitosan against the above-mentioned bacteria. However, higher doses of gamma irradiation (30 kGy and 40 kGy) caused a gradual decline of the antibacterial activity. Bangladesh J Microbiol, Volume 37 Number 2 December 2020, pp 52-55