Changes in microbial communities in a hybrid anaerobic reactor with organic loading rate and temperature

► Study of the effect of hydraulic and organic shock load on performance of hybrid anaerobic reactor. ► Analysis of the transition of archaeal and bacterial community profile to shock loads using 16S rRNA based PCR-DGGE method. ► Diverse community at 37 °C leads to better tolerance of higher shock load. ► Different response of microbial community and reactor performance to shocks. ► Reactors with longer HRT were able to withstand higher organic loads.