Mutation breeding of chitosanase-producing strain Bacillus sp. S65 by low-energy ion implantation

Abstract

In order to obtain an industrial strain with higher chitosanase yield, the wild strain Bacillus sp. S65 cells were mutated by a novel mutagen, nitrogen ion beam, with energy of 15 keV and dose ranging from 2.6 × 1014 to 5.2 × 1015 ions/cm2. One mutant, s65F5 with high yield of chitosanase was isolated. Results showed that the production of chitosanase of s65F5 was dramatically increased from 4.1 U/ml in s65 to 25 U/ml by ion beam implantation, while the fermentation time was shortened from 72 to 56 h, both of which greatly increased efficiency and reduced the cost of industrial production. Besides, the mutagenic e V ects of low-energy ion beam on survival rate showed characteristic down-up-down pattern, which was diVerent from the traditional mutagens such as UV and γ-ray and the possible mutation mechanism was discussed. © Society for Industrial Microbiology 2006.