Phototrophic Lactate Utilization by Is Stimulated by Coutilization with Additional Substrates.

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.