Growth strategy of microbes on mixed carbon sources

Abstract

A classic problem in microbiology is that bacteria display two types of growth behavior when cultured on a mixture of two carbon sources: the two sources are sequentially consumed one after another (diauxie) or they are simultaneously consumed (co-utilization). The search for the molecular mechanism of diauxie led to the discovery of the lac operon. However, questions remain as why microbes would bother to have different strategies of taking up nutrients. Here we show that diauxie versus co-utilization can be understood from the topological features of the metabolic network. A model of optimal allocation of protein resources quantitatively explains why and how the cell makes the choice. In case of co-utilization, the model predicts the percentage of each carbon source in supplying the amino acid pools, which is quantitatively verified by experiments. Our work solves a long-standing puzzle and provides a quantitative framework for the carbon source utilization of microbes.

The effects of environmental complexity on microbial community yield and structure

“…We found that all four of our organisms experienced cases of higher than expected yields on double vs. single nutrients (Supplementary Figure 13), which may reflect capabilities of the organisms to more efficiently fulfill metabolic requirements using multiple nutrients. Our observation parallels previous instances of this effect in microbial growth rates 33,39,40 , which we also corroborated using a timecourse experiment (Supplementary Figure 14). Thus, it seems plausible that the increases in ( we observed with increasing environmental complexity are at least in part due to the nonlinear nature of metabolism itself, along with ecological effects.…”

“…These nonlinearities were also displayed by our communities on individual carbon sources (Supplementary Figure 10), as well as in previous studies 20,21 . Additionally, we found evidence that a similar effect could be observed for microbial growth rates ( Supplementary Figure 11), as reported previously 22,30,31 . Therefore, the increases in " may at least be partially due to the nonlinear nature of metabolism itself.…”

Growth inhibition of Fusarium solani and F. oxysporum by Streptomyces sasae TG01, and its ability to solubilize insoluble phosphate

“…Glucose and lactose are both highly preferable carbon sources for E. coli, both supporting large growth rates. Fructose, glycerol, maltose, and galactose are less preferred (Wang et al 2019), but isolate TG01 can use fructose as good as glucose.…”

The mRNA derived MalH sRNA contributes to alternative carbon source utilization by tuning maltoporin expression in E. coli

“…Although catabolisable amino acids are the main carbon source that support growth in LB [9], LB also contains sugar mixtures in short supply, which made it an ideal medium for our studies on nutrient limitation. These sugars are consumed one after another or co-utilized in E. coli cultures depending on their hierarchy and concentration [5,10,63]. Glucose, the preferred carbon source, is consumed first, followed by other fermentable sugars such as maltodextrins, nucleotides, and free sugars.…”