Low molecular weight chitosan prepared with the aid of cellulase, lysozyme and chitinase: Characterisation and antibacterial activity

A continuous set of low molecular weight chitosan (LMWC) products was successfully made for this study by coordinating three enzymes (chitinase, lysozyme and cellulase) and two different deacetylated chitosan substrates (80% and 92%). It was observed that the intrinsic viscosity molecular weight (MV) and SEC-HPLC-determined MW distribution of LMWC were directed by both the used enzyme and the degree of chitosan substrate acetylation. LMWC prepared using lysozyme and 92%-deacetylated chitosan had larger MW and, therefore, possessed higher antibacterial activity, as compared to other combinations. LMWC enzyme-directed properties suggest chitinase is more predictable and flexible to produce the specified MV of LMWC. LMWC’s solubility and antibacterial activity, determined as minimum inhibitory concentration (MIC), against Escherichia coli exhibited a negative linear relationship with log MV. E. coli strains showed much higher susceptibility to LMWCs than Staphylococcus aureus strains did. Both species also showed intra-species sensitivity diversity toward LMWC.