PRODUCTION OF 2 CHITOSANASES FROM A CHITOSAN-ASSIMILATING BACTERIUM, ACINETOBACTER SP STRAIN-CHB101

A bacterial strain capable of utilizing chitosan as a sole carbon sour ce was isolated from soil and was identified as a member of the genus Acinetobacter. This strain, designated CWB101, produced extracellular chitosan-degrading enzymes in the absence of chitosan. The chitosan-de grading activity in the culture fluid increased when cultures reached the early stationary phase, although the level of activity was low in the exponential growth phase, Two chitosanases, chitosanases I and II, which had molecular weights of 37,000 and 30,000, respectively, were purified from the culture fluid. Chitosanase I exhibited substrate spe cificity for chitosan that had a low degree of acetylation (10 to 30%) , while chitosanase II degraded colloidal chitin and glycol chitin, as well as chitosan that had a degree of acetylation of 30%. Rapid decre ases in the viscosities of chitosan solutions suggested that both chit osanases catalyzed an endo type of cleavage reaction; however, chitosa n oligomers (molecules smaller than pentamers) were not produced after a prolonged reaction.