Antimicrobial effect of chitooligosaccharides produced by bioreactor

The antibacterial effect of three kinds of chitooligosaccharides with relatively higher molecular weights (HMWCOS), medium molecular weight (MMWCOS), and lower molecular weight (LMWCOS), respectively, was evaluated against various microorganisms. The oligosaccharides were prepared from chitosan and fractionated using ultrafiltration (UF) membrane in conjunction with an enzymatic bioreactor. The growth of most bacteria tested was inhibited by chitooligosaccharide treatments, in particular by HMWCOS, although chitosan treatment showed a better inhibitory effect. From the results here, the molecular weight of chitooligosaccharides is critical for microorganism inhibition 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 rights reserved.