低能N^+离子注入诱变选育琼胶酶高产菌株

Mutant breeding of high-activity agarase producing strains by low-energy N^+ ion implantation

对产琼胶酶的类芽孢杆菌(Paenibacillus sp.)菌株WL进行N+离子注入诱变,寄以筛选获得高活力琼胶酶产生菌株.首先考察了N+离子注入剂量对类芽孢杆菌WL存活率的影响,在注入能量为10keV的条件下,类芽孢杆菌WL菌株最佳剂量范围为15.6×1014～23.4×1014 ion/cm2.在23.4×1014 ion/cm2诱变剂量下,筛选得到1株高产琼胶酶的菌株WL-15,酶活力达到47.3U/mL,较出发菌株提高53.6%,该菌株经5次传代培养,产酶活力稳定.之后优化了产酶培养基中的主要成分,在琼胶、NaNO3和NaCl的质量浓度分别为2.5g/L,6.0g/L,15.0g/L时,类芽孢杆菌WL-15产酶活力达到了53.3U/mL.

For screening high-activity agarase producing strains, Paenibacillus sp. WL was mutated by implanting low-energy N^＋. At first, the effect of implanting dose of N＋ on survival rate of Paenibacillus sp. WL cells was investigated. The result showed that when the energy N＋ beam was l0 keV, the implanted dose in the range of 15.6× 10^14 -23.4× 10^14 ion/cm^2was the best one for Paenibacillus sp.. Under the implanted dose of 23.4 × 10^14 ion/cm^2 , a mutant strain Paenibacillus sp. WL-15 was screened out, which produced agarase with the activity of 47.3 U/mL and is 53. 6% higher than original strain. The property of producing high active agarase of WL-15 was stable after 5 generation transfer inoculation. Afterward, the concentrations of the main components in fermentation medium were optimized to improve the agarase activity. When the concentration of agar, NaNO3 and NaCl were 2.5 g/L, 6.0 g/L and 15.0 g/L respectively, the agarase activity could reach 53.3 U/mL.