氮离子束注入诱变选育胞外多糖高产菌株

Mutation breeding of high-yield exopolysaccharide-producing strains by nitrogen ion beam implantation

采用氮离子束注入胞外多糖产生菌进行诱变处理来获得胞外多糖高产菌株。氮离子注入过程采用的能量为10 keV,剂量为60×1014–140×1014cm-2。根据其存活率及突变率确定最佳的注入剂量。结果表明:菌株存活率曲线遵循氮离子注入生物效应的"马鞍型曲线",当注入剂量为120×1014cm-2时,获得了最佳的诱变效果。通过筛选和连续5次传代,获得具有良好稳定性的突变株,其多糖产量达到3.29 g/L,较出发菌株提高了19.20%,且发酵周期缩短了6 h。

The spores of strain producing exopolysaccharide were mutated by N＋ ions implantation to obtain a high-yield strain of exopolysaccharide in this study. The used energy and dose during the implantation process was about 10 keV and 60 × 10^14-140× 10^14 cm-2, respectively. The optimal dose was decided by the livability and mutation rate of the strain. It was found that the curve of survival took a ＂saddle shape＂ with increasing N＋ ion dose. The best induced mutation action was obtained when the ions implantation dose was 120x 1014 cm-2. After the selection and 5 generations of propagation, the mutant strain with high stability was obtained, whose exopolysaccharide yield reached 3.29 g/L, which was about 19.20% higher than that of the original strain, and the fermentation time was decreased by 6h.