双氧水对地衣芽胞杆菌合成杆菌肽的影响

Effects of H_2O_2 addition on bacitracin production by Bacillus licheniformis LC-11

在研究地衣芽胞杆菌浊液发酵生产杆菌肽过程中发现存在发酵前期溶氧为零、发酵中期菌体自溶以及二次生长现象,而H2O2是一种携氧剂,可释放O2以及不影响产物分离,因此在10L罐上,考察了流加H2O2对地衣芽胞杆菌浊液发酵合成杆菌肽的影响。在发酵24h时以速率为3mmol(/L.h)恒速流加H2O2至34h,菌体生物量在34h达到最大值为73.5×109cfu/mL比对照最大值高6.5%(对照最高值为69×109cfu/mL),自溶时间延后了8h,而且细胞自溶后的菌数最小值为42h的62.1×109cfu/mL,比对照自溶后最低值高了77%。24h^34h的挥发性脂肪酸(VFA)最高值为12.8g/L,比对照减少了11%,糖耗速率是0.36g(/L.h),比对照提高了3%。杆菌肽在24h^34h的合成速率为44.9U(/mL.h)比对照高12%(对照为40.1U(/mL.h)),杆菌肽最终效价为1021U/mL,比对照提高9.9%,说明适量流加H2O2不仅改善了细胞的生长环境,还能促进杆菌肽的生物合成效率。

In the research of batch cultures of Bacillus licheniformis LC-11 for bacitracin production, the phenomena that a low level of dissolved oxygen（DO） at the early phage of cultivation, cell lysis and secondary growth were observed. H202, a kind of carrying oxygen agent, can enhance the DO in batch culture and not influence the product purification, therefore, the effects of H20： addition on the bacitracin production by Bacillus licheni- formis LC-11 in a 10L bioreactor were investigated. H202 addition with a rate of 3mmol/（L＂ h） from 24h to 34h facilitated the cell growth, and the biomass reached the max value （73.5xl 09cfu/mD at 34h, which was 6.5% higher than that of the control. The time of cell lysis was delayed 8h, and the lowest cell biomass after cell lysis was 62x109cfu/ml at 42h, which was enhanced by 77% compared with the control. The volatile fatty acid （VFA） content reached the max value （12.8g/L） during 24h-34h, which was 11% lower than the control. The glucose consumption rate was 0.36g/（L.h） that was 3% higher than the control. The bacitarcin production rate was 44.9U/（ml·h） that was 12% higher than the control （40.1 U/（ml ·h）） during 24h-34h. The bacitracin production was 1021U/ml that was 9.9% higher than the control. The results suggested the H202 addition promoted cell growth and increased bacitracin biosynthesis efficiency.