Plasticity of growth laws tunes resource allocation strategies in bacteria

by Avik Mukherjee, Yu-Fang Chang, Yanqing Huang, Nina Catherine Benites, Leander Ammar, Jade Ealy, Mark Polk, Markus Basan Bacteria likeE.coli grow at vastly different rates on different substrates, however, the precise reason for this variability is poorly understood. Different growth rates have been attributed to ‘nutrient quality’, a key parameter in bacterial growth laws. However, it remains unclear to what extent nutrient quality is rooted in fundamental biochemical constraints like the energy content of nutrients, the protein cost required for their uptake and catabolism, or the capacity of the plasm a membrane for nutrient transporters. Here, we show that while nutrient quality is indeed reflected in protein investment in substrate-specific transporters and enzymes, this is not a fundamental limitation on growth rate, at least for certain ‘poor’ substrates. We show that it is possible to tu rn mannose, one of the ‘poorest’ substrates ofE.coli, into one of the ‘best’ substrates by reengineering chromosomal promoters of the mannose transporter and metabolic enzymes required for mannose degradation. This result falls in line with previous observations of more subtle growth rate improvement for many other carbon sources. However, we show that this faster growth rate comes at the cost of diverse cellular capabilities, reflected in longer lag phases, worse starvation survival and lower motility. We show that addition of cAMP to the medium can rescue these ph...
Source: PLoS Computational Biology - Category: Biology Authors: Source Type: research