M. Shimosaka et al., PRODUCTION OF 2 CHITOSANASES FROM A CHITOSAN-ASSIMILATING BACTERIUM, ACINETOBACTER SP STRAIN-CHB101, Applied and environmental microbiology, 61(2), 1995, pp. 438-442
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.