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 (M-v) and SEC-HPLC-determined M-w 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 M-v 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. (C) 2009 Elsevier Ltd. All rights reserved.