Screening and breeding by induced mutation of xylanase-producing marine microorganism

With self- made xylan as the only carbon source of primary screening medium,totally 60 strains which showed transparent zones and different morphology were screened from different marine samples. The shake flask fermentation results showed that 38 strains had xylanase- producing capabilities and strain B659 had the highest xylanase activity of 525. 3 U·m L- 1. Via morphological characteristics and 16 S r DNA sequence analysis,strain B659 was identified as Bacillus. The stable mutant strain G3- 17 with 13. 9% enhancement of xylanase activity was screened from the UV mutagenesis of strain B659. A stable mutant strain W1- 40 with 11. 6% xylanase activity increase was obtained by microwave mutation and screening from strain G3- 17. In 72 h fermentation of strain B659 and strain W1- 40,the xylanase activity of latter( 645. 2 U·m L- 1) achieved 24. 6% elevation than the former( 517. 9 U·m L- 1).