摘要
本实验采用同步辐射软X射线Nk诱变米根霉,获得一株新霉素抗性突变株NA-2,该菌株F1-ATPase活性降低86.82%,胞内ATP含量下降18.99%,最终菌体浓度为出发菌株的79.22%,发酵周期缩短了12h,葡萄糖平均消耗速度和L-乳酸生产强度分别高出25.17%和32.57%,平均葡萄糖消耗比速(qs)、L-乳酸生成比速(qp)和细胞比生长速率(μ)分别提高86.42%、128.13%和60.0%,但胞内能荷变化不明显。进一步研究发现,突变株糖酵解途径中关键酶磷酸果糖激酶(PEK)、丙酮酸激酶(PK)和磷酸甘油醛激酶(GAPDH)的活性较原始菌株提高了58.34%、23.53%和11.29%,乙醇脱氢酶(ADH)活性降低了32.11%,乳酸脱氢酶(LDH)活性提高了42.27%。结果表明,降低米根霉F1-ATPase活性有效地提高了糖酵解关键酶活性而加速葡萄糖代谢,提高了L-乳酸生产强度。
A neomycin-resistant mutant NA-2, with the activity of F1-ATPase decreased roughly 86.82%, was obtained by synchrotron soft X-ray Nk mutagenesis based on analysis of energy metabolic pathway. The strain NA-2 was cultured in a flask containing L-lactic acid fermentation medium with 120 g/L glucose. It was found that compared with the fermentation characters of original Rhizopus oryza, the rates of glucose consumption and L-lactic acid production are higher with 25.17% and 32.57%, and the q,, qpand μ are higher 86.42%, 128.13% and 60.0% respectively. The content ofintracellular ATP decreases 18.99% in the mutant than in the origin. However, the change ofintracellular energy charge is not obvious. The activities of key enzymes in glycoly ticpathway of the mutant and the origin were determined. Results showed that, compared with the original strainRhizopus oryzae 3.819, the activities of key enzymes, phosphofructokinase, private kinas, glyceraldyde-3-phosphate dehydrogenase of the mutant NA-2 increase 58.34%, 23.53% and 11.29%, respectively. The activity of LDH increase 42.27% while that of ADH decreases 32.11%. As a conclusion, the L-lactic acid productivity by Rhizopus oryza3.819 is enhanced when the activities of key enzymes in glycdytic pathway are regulated by decreasing the activity of F1 -ATPase.
出处
《食品科学》
EI
CAS
CSCD
北大核心
2008年第11期442-446,共5页
Food Science
基金
国家高技术研究发展计划"863"项目(2007AA10Z361)
合肥工业大学校基金项目(063001F)
