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 x 10(14 )to 5.2 x 10(15) ions/cm(2). 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 effects of low-energy ion beam on survival rate showed characteristic down-up-down pattern, which was different from the traditional mutagens such as UV and gamma-ray and the possible mutation mechanism was discussed.