Hierarchical and simultaneous utilization of carbon substrates: mechanistic insights, physiological roles, and ecological consequences. (October 2021)

• Record Type: Journal Article
• Authors: Okano, Hiroyuki; Hermsen, Rutger; Hwa, Terence
• Is Part Of: Current opinion in microbiology. Volume 63(2021)
• Page Start: 172
• Page End: 178
• Publication Date: 2021-10
• Subjects: Microbiology -- Periodicals; 579.05
• DOI: 10.1016/j.mib.2021.07.008
• Languages: English
• ISSNs: 1369-5274

Abstract

Highlights: Utilization patterns on mixed carbon substrates depend on growth rates on individual substrates and their entering points into metabolism. Flux-based regulation serves as a general mechanism to implement hierarchical utilization and accounts for its condition dependence. Growth-rate optimization with a resource constraint is insufficient to account for the physiological roles of different utilization patterns. Consumer-resource models with a resource allocation constraint suggest that hierarchical utilization can increase biodiversity. Abstract : Bacteria grown on a mixture of carbon substrates exhibit two utilization patterns: hierarchical utilization (HU) and simultaneous utilization (SU). How and why cells adopt these different behaviors remains poorly understood despite decades of research. Recent studies address various open questions from multiple viewpoints. From a mechanistic perspective, it was found that flux sensors play a central role in the regulation of substrate utilization, accounting for the known dependences on single-substrate growth rates, substrate concentrations, and the point where the substrate enters central metabolism. From a physiological perspective, several recent studies suggested HU or SU as growth-optimizing strategies through efficient allocation of essential proteome resources. However, other studies demonstrate that a significant fraction of the proteome is dedicated to functions apparently unnecessary for growth, casting doubt on explanations based on slight efficiency gains. From an ecological perspective, recent theoretical studies suggest that HU can help increase species diversity in bacterial communities.