摘要
利用大肠杆菌厌氧制备丁二酸过程中,采用氨水作为p H调节剂不仅可以中和酸性产物还可提供无机氮,被菌体利用,然而高浓度NH_4^+的积累会抑制菌体生长及代谢产酸的能力。为增强大肠杆菌对高浓度NH_4^+的耐受性,以(NH4)2HPO4为NH_4^+供体,通过在连续培养装置中不断提高(NH_4)_2HPO4浓度,以获得可耐受0.53 mol/L NH_4^+的产丁二酸大肠杆菌。结果表明:突变株在0.53 mol/L NH_4^+胁迫下,摇瓶厌氧发酵72 h,细胞干质量浓度(DCW)可达1.82 g/L,丁二酸产量为11.72 g/L,分别比出发菌株提高了1.6和4.6倍。进一步地,在5 L发酵罐上考察其利用氨水调节p H生产丁二酸的能力,厌氧发酵90 h,丁二酸质量浓度达到27.32 g/L,生产强度为0.30g/(L·h),比出发菌株分别提高88.1%和87.5%。
During the process of succinic acid production by Escherichia coli, ammonia was adopted as pH regulator, not only could neutralize organic acid but also as nitrogen source for growth. However, high concentration of NH4 would seriously inhibit the growth and metabolic capability of the strain.To improve the tolerance of E. coli towards high amount of NH4, metabolic evolution was used for isolation of ammonium-tolerant mutants by enhancing the concentration of NH~ gradually which was provided from （NH4） 2HPO4.Finally,a mutant which could tolerant 0. 53 mol/L NH~ was obtained.The results showed when under O. 53 mol/L NH4 in flask, dry cell weight of the mutant reached 1.82 g/L and succinic acid concentration reached 11.72 g/L within 72 h fermentation, which was 1.6- and 4. 6-fold compared with the parent strain respectively. Furthermore, the ability of the mutant using ammonia as pH regulator for succinic acid production was investigated in a 5-L fermentor. After 90 h fermentation, concentration and productivity of succinic acid reached 27.32 g/L and 0. 30 g/（L-h） ,which were increased by 88.1% and 87.5% compared with the parent strain.
出处
《生物加工过程》
CAS
2015年第6期55-60,共6页
Chinese Journal of Bioprocess Engineering
基金
国家重点基础研究发展计划(973计划)(2013CB733901)
江苏省高校优势学科建设工程
关键词
进化代谢
耐铵
丁二酸
大肠杆菌
metabolic evolution
ammonium-tolerant
succinic acid
Escherichia coli
