Systematic variation in the temperature dependence of bacterial carbon use efficiency

Abstract

Carbon use efficiency (CUE) is a key characteristic of microbial physiology and underlies community‐level responses to changing environments. Yet, we currently lack general empirical insights into variation in microbial CUE at the level of individual taxa. Here, through experiments with 29 strains of environmentally isolated bacteria, we find that bacterial CUE typically responds either positively to temperature, or has no discernible response, within biologically meaningful temperature ranges. Using a global data synthesis, we show that these results are generalisable across most culturable groups of bacteria. This variation in the thermal responses of bacterial CUE is taxonomically structured, and stems from the fact that relative to respiration rates, bacterial population growth rates typically respond more strongly to temperature, and are also subject to weaker evolutionary constraints. Our results provide new insights into microbial physiology, and a basis for more accurately modelling the effects of thermal fluctuations on complex microbial communities.

Latent functional diversity may accelerate microbial community responses to temperature fluctuations

“…These differences in metabolic strategies reflect underlying differences in the efficiency of growth, i.e. carbon use efficiency (CUE), between these taxa [41]. Moreover, CUE varies systematically with temperature, in a phylogenetically structured manner [58,41].…”

“…e . carbon use efficiency (CUE), between these taxa [41]. Moreover, CUE varies systematically with temperature, in a phylogenetically structured manner [58, 41].…”

“…carbon use efficiency (CUE), between these taxa [41]. Moreover, CUE varies systematically with temperature, in a phylogenetically structured manner [58, 41]. Thus, community turnover due to temperature change is likely to have a profound impact on community-level functional traits, such as CUE [59].…”

“…This is a colorimetric assay initially developed to measure CO 2 production from soil samples, which has since been used to measure respiration of bacterial cultures [38, 39, 40]. We calculate the biomass-specific respiration rate using an equation that accounts for changes in biomass of the growing cultures over time [41]: …”

“…1 for T = T pk . This model was fitted to each dataset using a standard non-linear least squares procedure [41].…”