Tallinn University of Technology, Department of Chemistry and Biotechnology, Akadeemia tee 15, 12618, Tallinn, Estonia; Center of Food and Fermentation Technologies, Mäealuse 2/4, 12618, Tallinn, Estonia.
University of Tartu, Institute of Technology, Nooruse 1, 50411, Tartu, Estonia.
Anaerobe. 2023 Feb;79:102680. doi: 10.1016/j.anaerobe.2022.102680. Epub 2022 Dec 5.
Human gut microbiota species which are next-generation probiotics (NGPs) candidates are of high interest as they have shown the potential to treat intestinal inflammation and other diseases. Unfortunately, these species are often not robust enough for large-scale cultivation, especially in maintaining diversity in co-culture production.
In this study, we describe interactions between human gut microbiota species in the cultivation process with unique substrates. We also demonstrated that it is possible to change the species ratio in co-culture by changing the ratio of carbon sources.
We screened 25 different bacterial species based on their metabolic capabilities. After evaluating unique substrate possibilities, we chose Anaerostipes caccae (A. caccae), Bacteroides thetaiotaomicron (B. thetaiotaomicron), and Bacteroides vulgatus (B. vulgatus) as subjects for further study. D-sorbitol, D-xylose, and D-galacturonic acid were selected as substrates for A. caccae, B. thetaiotaomicron, and B. vulgatus respectively. All three species were cultivated as both monocultures and in co-cultures in serial batch fermentations in an isothermal microcalorimeter.
Positive interactions were detected between the species in both co-cultures (A. caccae + B. thetaiotaomicron; A. caccae + B. vulgatus) resulting in higher heat production compared to the sum of the monocultures. The same positive cross-feeding interactions took place in larger-scale cultivation experiments. We confirmed acetate and lactate cross-feeding between A. caccae and B. thetaiotaomicron with flux balance analysis (FBA).
Changing the ratio of the selected carbon sources in the medium changed the species ratio accordingly. Such robustness is the basis for developing more efficient industrial co-culture processes including the production of NGPs.
具有下一代益生菌（NGP）候选潜力的人类肠道微生物物种受到高度关注，因为它们已显示出治疗肠道炎症和其他疾病的潜力。不幸的是，这些物种通常不够健壮，无法进行大规模培养，尤其是在维持共培养生产中的多样性方面。
在本研究中，我们描述了在使用独特底物的培养过程中人类肠道微生物物种之间的相互作用。我们还证明，通过改变碳源的比例，可以改变共培养物中的物种比例。
我们根据代谢能力筛选了 25 种不同的细菌物种。在评估了独特的基质可能性之后，我们选择了厌氧梭菌（A. caccae）、拟杆菌（B. thetaiotaomicron）和脆弱拟杆菌（B. vulgatus）作为进一步研究的对象。D-山梨醇、D-木糖和 D-半乳糖醛酸分别被选为 A. caccae、B. thetaiotaomicron 和 B. vulgatus 的底物。这三种细菌均在等温微量热计中进行了连续批量发酵，分别在单培养和共培养中进行了培养。
在共培养物（A. caccae + B. thetaiotaomicron；A. caccae + B. vulgatus）中检测到物种之间存在正相互作用，与单培养相比，产生的热量更高。在更大规模的培养实验中也发生了相同的正交叉喂养相互作用。我们通过通量平衡分析（FBA）确认了 A. caccae 和 B. thetaiotaomicron 之间的乙酸盐和乳酸盐交叉喂养。
改变培养基中选定碳源的比例会相应地改变物种比例。这种稳健性是开发更有效的工业共培养工艺（包括生产 NGP）的基础。
