Antimicrobial effect of chitooligosaccharides produced by bioreactor

The antibacterial effect of three kinds of chitooligosaccharides with relat ively higher molecular weights (HMWCOS), medium molecular weight (MMWCOS), and lower molecular weight (LMWCOS), respectively, was evaluated against va rious microorganisms. The oligosaccharides were prepared from chitosan and fractionated using ultrafiltration (UF) membrane in conjunction with an enz ymatic bioreactor. The growth of most bacteria tested was inhibited by chit ooligosaccharide treatments, in particular by HMWCOS, although chitosan tre atment showed a better inhibitory effect. From the results here, the molecu lar weight of chitooligosaccharides is critical for microorganism inhibitio n and required higher than 10,000 Da. Generally, the chitooligosaccharides have more effective activity against pathogens than nonpathogens, except in the case of lactic acid bacteria. (C) 2001 Elsevier Science Ltd. All right s reserved.