Bacterial function and community structure in reactors treating biopolymers and surfactants at mesophilic and thermophilic temperatures

Microbial communities capable of degrading biopolymers and surfactants typically found in graywater were selected in continuous-flow bioreactors operated at 30, 44, 53, or 62°C. The effect of temperature upon microbial activity and community composition was determined. Microbial respiration of the organic components of the medium (including linear alkylbenzene sulfonate) was detected in samples from each reactor. The microbial community in each reactor was adapted to the operating temperature. Nucleic acid-based analyses of community composition showed that distinct consortia were present at each temperature. Community complexity was inversely related to temperature. The specific maintenance rate was twofold higher at 62°C than at the lower temperatures. Under starvation conditions, microbes in the 62°C system lost membrane integrity 30- to 100-fold faster than microbes at lower temperatures.