Abstract:

In order to obtain a high-yield β-1,3-1,4-glucanase producing strain, Bacillus altitudinis YC-9 was used as the
starting strain and mutagenized sequentially with nitrosoguanidine (NTG) and N+ beam. The preliminary and secondary
screening results showed that strain N-2-2 and 10-30s-3 had high ability to produce β-1,3-1,4-glucanase, with a yield of 28.6
and 36.1 U/mL, which revealed a 2.36- and 2.98-fold increase compared with that of the original strain, respectively, while
exhibiting reduced growth rates. Furthermore, the β-1,3-1,4-glucanase gene was successfully cloned and expressed in E. coli.
The intracellular activity was 79.2 U/mL, a 6.5-fold increase compared with the original strain, when induced at 30 ℃ for 6 h.

Key words: Bacillus altitudinis, β-1,3-1,4-glucanase, nitrosoguanidine (NTG) mutagenesis, N+ beam implantation, heterologous expression