Department of Biotechnology, Delft University of Technology, Delft, The Netherlands.
Department of Chemical Engineering, Institute of Technology, Universidade de Santiago Compostela, Santiago de Compostela, Spain.
Biotechnol Bioeng. 2020 May;117(5):1281-1293. doi: 10.1002/bit.27301. Epub 2020 Feb 18.
Lactic acid-producing bacteria are important in many fermentations, such as the production of biobased plastics. Insight in the competitive advantage of lactic acid bacteria over other fermentative bacteria in a mixed culture enables ecology-based process design and can aid the development of sustainable and energy-efficient bioprocesses. Here we demonstrate the enrichment of lactic acid bacteria in a controlled sequencing batch bioreactor environment using a glucose-based medium supplemented with peptides and B vitamins. A mineral medium enrichment operated in parallel was dominated by Ethanoligenens species and fermented glucose to acetate, butyrate and hydrogen. The complex medium enrichment was populated by Lactococcus, Lactobacillus and Megasphaera species and showed a product spectrum of acetate, ethanol, propionate, butyrate and valerate. An intermediate peak of lactate was observed, showing the simultaneous production and consumption of lactate, which is of concern for lactic acid production purposes. This study underlines that the competitive advantage for lactic acid-producing bacteria primarily lies in their ability to attain a high biomass specific uptake rate of glucose, which was two times higher for the complex medium enrichment when compared to the mineral medium enrichment. The competitive advantage of lactic acid production in rich media can be explained using a resource allocation theory for microbial growth processes.
产乳酸细菌在许多发酵过程中很重要，例如生物基塑料的生产。了解混合培养中产乳酸细菌相对于其他发酵细菌的竞争优势，可以实现基于生态学的过程设计，并有助于开发可持续和节能的生物工艺。在这里，我们使用基于葡萄糖的培养基，补充肽和 B 族维生素，在受控的序批式生物反应器环境中展示了产乳酸细菌的富集。同时进行的矿物培养基富集以 Ethanoligenens 物种为主，将葡萄糖发酵为乙酸盐、丁酸盐和氢气。复杂培养基的富集由乳球菌、乳杆菌和巨大球型菌组成，表现出乙酸盐、乙醇、丙酸盐、丁酸盐和戊酸盐的产物谱。观察到乳酸的中间峰，表明乳酸的同时生产和消耗，这对于乳酸生产目的是有问题的。本研究强调，产乳酸细菌的竞争优势主要在于它们能够达到葡萄糖的高生物质比吸收速率，与矿物培养基富集相比，复杂培养基富集的葡萄糖生物质比吸收速率高两倍。在丰富的培养基中进行乳酸生产的竞争优势可以用微生物生长过程的资源分配理论来解释。
