Microbiology Undergraduate Program, Indiana University, Bloomington, Indiana, USA.
Biotechnology Undergraduate Program, Indiana University, Bloomington, Indiana, USA.
Appl Environ Microbiol. 2019 May 16;85(11). doi: 10.1128/AEM.00048-19. Print 2019 Jun 1.
The phototrophic purple nonsulfur bacterium is known for its metabolic versatility and is of interest for various industrial and environmental applications. Despite decades of research on growth under diverse conditions, patterns of growth and carbon utilization with mixtures of carbon substrates remain largely unknown. readily utilizes most short-chain organic acids but cannot readily use lactate as a sole carbon source. Here we investigated the influence of mixed-substrate utilization on phototrophic lactate consumption by We found that lactate was simultaneously utilized with a variety of other organic acids and glycerol in time frames that were insufficient for growth on lactate alone. Thus, lactate utilization by was expedited by its coutilization with additional substrates. Separately, experiments using carbon pairs that did not contain lactate revealed acetate-mediated inhibition of glycerol utilization in This inhibition was specific to the acetate-glycerol pair, as simultaneously utilized acetate or glycerol when either was paired with succinate or lactate. Overall, our results demonstrate that (i) commonly employs simultaneous mixed-substrate utilization, (ii) mixed-substrate utilization expands the spectrum of readily utilized organic acids in this species, and (iii) has the capacity to exert carbon catabolite control in a substrate-specific manner. Bacterial carbon source utilization is frequently assessed using cultures provided single carbon sources. However, the utilization of carbon mixtures by bacteria (i.e., mixed-substrate utilization) is of both fundamental and practical importance; it is central to bacterial physiology and ecology, and it influences the utility of bacteria as biotechnology. Here we investigated mixed-substrate utilization by the model organism Using mixtures of organic acids and glycerol, we show that exhibits an expanded range of usable carbon substrates when provided substrates in mixtures. Specifically, coutilization enabled the prompt consumption of lactate, a substrate that is otherwise not readily used by Additionally, we found that utilizes acetate and glycerol sequentially, revealing that this species has the capacity to use some substrates in a preferential order. These results provide insights into physiology that will aid the use of for industrial and commercial applications.
光养型紫色无硫细菌以其代谢多样性而闻名，对于各种工业和环境应用具有重要意义。尽管对其在不同条件下的生长进行了数十年的研究，但对于混合碳底物的生长和碳利用模式仍知之甚少。该菌容易利用大多数短链有机酸，但不能轻易地将乳酸作为唯一的碳源。在这里，我们研究了混合底物利用对该菌光养型乳酸消耗的影响。我们发现，在不足以单独利用乳酸进行生长的时间框架内，乳酸与各种其他有机酸和甘油同时被利用。因此，通过与其他底物共同利用，促进了该菌对乳酸的利用。另外，使用不包含乳酸的碳对实验表明，在该菌中，乙酸盐会抑制甘油的利用。这种抑制作用是乙酸盐-甘油对特有的，因为当与琥珀酸盐或乳酸配对时，该菌同时利用乙酸盐或甘油。总的来说，我们的结果表明：（i）该菌通常采用同时混合底物利用；（ii）混合底物利用扩展了该物种中易利用有机酸的范围；（iii）该菌具有以底物特异性方式发挥碳分解代谢控制的能力。细菌碳源利用通常使用提供单一碳源的培养物进行评估。然而，细菌对碳混合物的利用（即混合底物利用）具有基础和实际的重要性；它是细菌生理学和生态学的核心，并且影响细菌作为生物技术的实用性。在这里，我们研究了模型生物 的混合底物利用。通过使用有机酸和甘油的混合物，我们表明，当提供混合物中的底物时，该菌表现出可利用的碳底物范围扩大。具体而言，共同利用使乳酸的快速消耗成为可能，乳酸是该菌不易利用的底物。此外，我们发现该菌依次利用乙酸盐和甘油，这表明该物种具有以优先顺序使用某些底物的能力。这些结果提供了对该菌生理学的深入了解，将有助于该菌在工业和商业应用中的使用。
