Chen Zhengang, Huang Liu, Ji Xiaofeng, Chen Ranran, Zhu Jiying
School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo, 255000, China.
School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo, Shandong, 255000, China.
Appl Biochem Biotechnol. 2025 Jul 16. doi: 10.1007/s12010-025-05334-w.
Chain elongation (CE) with lactic acid as electron donor is an important way for the biosynthesis of hexanoic acid, and pH is crucial for the carbon flow direction in the CE process. In this study, a high concentration of lactic acid was achieved through the pre-fermentation of Chinese cabbage wastes (CCW), and the effects of pH on the metabolic flow of lactic acid and hexanoic acid yield during CE reaction were investigated. The coexistence of Lactobacillus, Caproiciproducens, and Acinetobacter at pH 5.5 facilitated the CE process driven by lactic acid, obtaining the highest hexanoic acid yield of 5.01 ± 0.01 g COD/L. At pH 6.0, the high abundance of propionic acid-producing bacteria, such as Blautia and Succiniclasticum, converted lactic acid to propionic acid via the acrylate pathway, resulting in low selectivity of hexanoic acid. Without pH control, acetic acid was the main product due to the low pH at the initial stage of fermentation.
以乳酸作为电子供体的链延长（CE）是己酸生物合成的重要途径，并且pH值对于CE过程中的碳流方向至关重要。在本研究中，通过大白菜废弃物（CCW）的预发酵实现了高浓度乳酸，并研究了pH值对CE反应过程中乳酸代谢流和己酸产量的影响。在pH 5.5时，乳酸杆菌、产己酸菌和不动杆菌共存促进了由乳酸驱动的CE过程，获得了最高己酸产量5.01±0.01 g COD/L。在pH 6.0时，大量产丙酸细菌（如布劳特氏菌和琥珀酸分解菌）通过丙烯酸途径将乳酸转化为丙酸，导致己酸选择性较低。在不控制pH值的情况下，由于发酵初期pH值较低，乙酸是主要产物。
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