产酸克雷伯氏菌乳酸脱氢酶基因敲除提高2,3-丁二醇产量

基于传统发酵工艺，通过在发酵阶段进行菌种强化结合在蒸馏烤酒阶段进行工艺优化（头尾酒浸提菌剂后返回地锅蒸馏）提升酱香型白酒基酒中四甲基吡嗪（TTMP）的含量。结果表明，采用菌种强化、工艺优化及二者相结合的方法分别能将酱香型白酒基酒中四甲基吡嗪的含量提高160.71%、85.75%和202.75%。感官评价结果表明，菌种强化结合工艺优化的技术对基酒的感官风味影响不大。该研究提供了一种适合企业落地应用的进一步提高酱香型白酒基酒中四甲基吡嗪含量的方法和思路。

Knockout of lactate dehydrogenase gene in Klebsiella oxytoca to enhance 2,3-butanediol production

Lactate dehydrogenase (LDH) is a key enzyme in lactic acid production pathway, knockout of LDH gene can theoretically reduce or even eliminate the production of lactic acid, thereby increasing the production and yield of 2,3-butanediol. In this study, the homologous recombination linear sequence ldhL-Cmr-ldhR of LDH gene was constructed by the method of digestion and connection in vitro. After that, the ldhL-Cmr-ldhR was electrotransformed into Klebisella oxytoca HD79. The recombination strain was successfully screened by Red homologous recombination technology, and verified by polymerase chain reaction (PCR), fluorogenic quantitative-polymerase chain reaction (FQ-PCR) and 2,3-butanediol production detection. The results indicated that the 2,3-butanediol production, convert ratio and production intensity of the recombinant strain were 40.20 g/L, 0.38 g/g and 0.48 g/(L·h), respectively, which were 26.8%, 11.8%, 45.5% higher than that of the tested strain, respectively. However, the lactic acid production of recombinant strain decreased from 4.83 g/L to 2.45 g/L, which was 49.3% lower than that of the tested strain. It laid a foundation for further increasing the production of 2,3-butanediol and expanding the range of strain selection.