Mechanism for microbial population collapse in a fluctuating resource environment

Managing trade-offs through gene regulation is believed to confer resilience to a microbial community in a fluctuating resource environment. To investigate this hypothesis, we imposed a fluctuating environment that required the sulfate-reducer Desulfovibrio vulgaris to undergo repeated ecologically relevant shifts between retaining metabolic independence (active capacity for sulfate respiration) and becoming metabolically specialized to a mutualistic association with the hydrogen-consuming Methanococcus maripaludis. Strikingly, the microbial community became progressively less proficient at restoring the environmentally relevant physiological state after each perturbation and most cultures collapsed within 3–7 shifts. Counterintuitively, the collapse phenomenon was prevented by a single regulatory mutation. We have characterized the mechanism for collapse by conducting RNA-seq analysis, proteomics, microcalorimetry, and single-cell transcriptome analysis. We demonstrate that the collapse was caused by conditional gene regulation, which drove precipitous decline in intracellular abundance of essential transcripts and proteins, imposing greater energetic burden of regulation to restore function in a fluctuating environment.

Source: Molecular Systems Biology - March 19, 2017 Category: Molecular Biology Authors: Turkarslan, S., Raman, A. V., Thompson, A. W., Arens, C. E., Gillespie, M. A., von Netzer, F., Hillesland, K. L., Stolyar, S., Lopez Garcia de Lomana, A., Reiss, D. J., Gorman-Lewis, D., Zane, G. M., Ranish, J. A., Wall, J. D., Stahl, D. A., Baliga, N. S. Tags: Microbiology, Virology & Host Pathogen Interaction, Quantitative Biology & Dynamical Systems Articles Source Type: research