State Key Laboratory of Food Nutrition and Safety, Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China.
College of Biotechnology Engineering, Sichuan University of Science and Engineering, Yibin 644000, China.
J Ind Microbiol Biotechnol. 2024 Jan 9;51. doi: 10.1093/jimb/kuae036.
Pyrroloquinoline quinone (PQQ) is one of the important coenzymes in living organisms. In acetic acid bacteria (AAB), it plays a crucial role in the alcohol respiratory chain, as a coenzyme of alcohol dehydrogenase (ADH). In this work, the PQQ biosynthetic genes were overexpressed in Acetobacter pasteurianus CGMCC 3089 to improve the fermentation performance. The result shows that the intracellular and extracellular PQQ contents in the recombinant strain A. pasteurianus (pBBR1-p264-pqq) were 152.53% and 141.08% higher than those of the control A. pasteurianus (pBBR1-p264), respectively. The catalytic activity of ADH and aldehyde dehydrogenase increased by 52.92% and 67.04%, respectively. The results indicated that the energy charge and intracellular ATP were also improved in the recombinant strain. The acetic acid fermentation was carried out using a 5 L self-aspirating fermenter, and the acetic acid production rate of the recombinant strain was 23.20% higher compared with the control. Furthermore, the relationship between the PQQ and acetic acid tolerance of cells was analyzed. The biomass of recombinant strain was 180.2%, 44.3%, and 38.6% higher than those of control under 2%, 3%, and 4% acetic acid stress, respectively. After being treated with 6% acetic acid for 40 min, the survival rate of the recombinant strain was increased by 76.20% compared with the control. Those results demonstrated that overexpression of PQQ biosynthetic genes increased the content of PQQ, therefore improving the acetic acid fermentation and the cell tolerance against acetic acid by improving the alcohol respiratory chain and energy metabolism.
The increase in PQQ content enhances the activity of the alcohol respiratory chain of Acetobacter pasteurianus, and the increase in energy charge enhances the tolerance of cells against acetic acid, therefore, improving the efficiency of acetic acid fermentation.
吡咯并喹啉醌（PQQ）是生物体内重要的辅酶之一。在醋酸菌（AAB）中，它作为醇脱氢酶（ADH）的辅酶，在酒精呼吸链中起着至关重要的作用。在这项工作中，过表达了醋酸杆菌 CGMCC 3089 中的 PQQ 生物合成基因，以提高发酵性能。结果表明，重组菌 A. pasteurianus（pBBR1-p264-pqq）的细胞内和细胞外 PQQ 含量分别比对照 A. pasteurianus（pBBR1-p264）高 152.53%和 141.08%。ADH 和醛脱氢酶的催化活性分别提高了 52.92%和 67.04%。结果表明，重组菌的能量电荷和细胞内 ATP 也得到了改善。在 5 L 自吸式发酵罐中进行醋酸发酵，重组菌的醋酸产率比对照提高了 23.20%。此外，还分析了 PQQ 与细胞耐醋酸的关系。在 2%、3%和 4%的醋酸胁迫下，重组菌的生物量分别比对照高 180.2%、44.3%和 38.6%。用 6%的醋酸处理 40 分钟后，重组菌的存活率比对照提高了 76.20%。这些结果表明，过表达 PQQ 生物合成基因增加了 PQQ 的含量，从而通过改善酒精呼吸链和能量代谢，提高了醋酸发酵效率和细胞对醋酸的耐受性。
PQQ 含量的增加增强了醋酸杆菌酒精呼吸链的活性，提高了细胞的能量电荷，增强了细胞对醋酸的耐受性，从而提高了醋酸发酵效率。
