维生素C二步发酵中离子注入诱变巨大芽孢杆菌的生物学效应

Bio-effects of Bacillus megaterium Induced by Ion Implantation in Two-step Fermentation for Vitamin C

巨大芽孢杆菌BM279是经低能N+离子注入诱变原始菌株BM80而得到的维生素C高转化率伴生菌株。通过对离子注入前后出发菌和突变株的生理、生化等生物学特点比较,探讨了离子注入巨大芽孢杆菌对2-酮基-L-古龙酸(2KGA)高转化率的促进机理。离子注入对巨大芽孢杆菌自身的生长无明显影响,BM279呈现出与BM80基本一致的生长曲线;但BM279对混菌发酵体系中产酸菌GO29的细胞增殖有显著促进作用。BM279在混菌发酵过程中分泌较多的碱性物,有利于维持GO29生长、代谢的pH环境。BM279培养42 h,其胞外活性物质对GO29的糖酸转化活力较BM80有显著提高,且分泌时间较BM80推迟6 h。利用层析技术分别从BM80、BM279胞外液中纯化了L-山梨糖脱氢酶(L-sorbose dehydrogenase,SDH)激活蛋白(SSPBM80和SSPBM279),后者比活较前者高出50%,对GO29中的SDH酶活有更强促进作用。

Bacillus megaterium BM279 was the mutant strain induced by ion bean implantation from BM80. The bioeffects on the physiological and chemical level between BM279 and BM80 were discussed in this study. Ion beam implantation acted no effect on the growth of BM279 itself and exhibited the accordant growth curve with BM80. However, alkaline metabolism secreted by BM279 accelerated the proliferation of GO29 and facilitated to sustain the pH environment for GO29. The 42 h cultivated extra cellular active element from BM279 improved the acid-producing capacity of GO29 than that of BM80. Additionally, this active element from BM279 was excreted 6 h later than that of BM80. The SDH （L-sorbose dehyrogenase） simulative protein SSPBM80 and SSPBM279 from the extra cellular supernatant of BM80 and BM279 were purified by three chromatographic steps respectively. The specific activity of SSPBM279 was 50 percent higher than that of SSPBM80, and which subsequently accelerated the SDH activity of GO29.