| Bacillus licheniformis HDYM-03, which was isolated from the fermentation liquid of flax retting by the key lab of Heilongjiang university, could show the highest mannanase activity as 5122U/mL. To culture mannanase overproducing strains, the research include using different physical and chemical factors to induce HDYM-03 to mutation. After the original strain HDYM-03 was mutagenensised by UV,NTG,NTG combined UV and DES, by analyzing and comparing the mutative effects of different mutative factors, it was concluded that the mutative effects of NTG were better than other factors which the study used. The mutagenic experiments defined NTG mutant as parent strain (N10-46), then by means of NTG mutant, the fusion experiments obtained high-yield strain: N10-46-85. The activity of mannanase could reach 11651 U/mL.The optimum temperature and pH of unpurifiedβ–mannanase are respectively 40℃and 10.0, and theβ–mannanase is stable in the pH range of 10.0-11.0 and under 50℃. Most of metal ions have little effect onβ–mannanase.This research made a foundation for separation and purification of mannanase and also offered a strain source to enzyme production. HDYM-03 had advantages such as abundant enzymatic system, high enzyme activity and had a wide applied future in the field of biological-degumming. |
