Abstract:

Bacterial strains were isolated from coastal sandy soil collected in Yantai, Shandong province, and were initially
screened to obtain 5 chitosanase-producing strains by transparent circle method. Further secondary screening provided a
strain producing the highest chitosanase activity named amyP216. The strain amyP216 was identified as Bacillus mojavensis
based on morphological, physiological and biochemical characteristics and 16S rDNA sequence analysis. The fermentation
conditions of amyP216 for chitosanase production were optimized by one-factor-at-a-time and orthogonal array designs.
The results showed that the maximum chitosanase activity of 80.60 U/mL, which was increased by 2.2 folds as compared
to that before optimization (36.20 U/mL), was obtained when the fermentation was carried out at 30 ℃ for 45 h in a 5-L
auto-controlled fermentor using optimized culture medium containing 20 g/L colloid chitosan, 12.5 g/L yeast extract
powder and 1.0 g/L Tween-80 at initial pH 6.0. Therefore, the strain amyP216 has potential application in the industrial
production of chitosanase.

Key words: Bacillus mojavensis, chitosanase, chitosan oligosaccharide, isolation and identification, optimization of fermentation conditions