How does temperature regulate anaerobic digestion?

Temperature plays a primary role in anaerobic digestion, since it shapes microbial ecosystems, and consequently regulates the stability performance of anaerobic digestion process. Although changes in microbial community and composition at different temperatures have also previously been discussed in some experimental studies. However, until now, this aspect of the regulation of the temperature gradient on microbial communities have not yet well been reviewed. Additionally, these previous studies did not observe the classical three-peak model regarding methane production rates owing to limitations to the temperature range and the broad gradient interval. Furthermore, some microorganisms that lived at “extreme” temperatures have been reported in some previous studies, it provides a possibility for industrial applications of anaerobic digestion in cold regions or for sanitation purposes on the basis of deciphering the mechanism of their adaption. This survey aims to shove the boundaries a little further summarizing an overview of the microbial responses to the fermentation temperature gradient in each step (including hydrolysis, acidification, and methanogenesis) of the anaerobic digestion process and investigated the mechanism of adaption to extreme temperature regimes. Overall, this review covers discussion on microorganisms’ responses to broad temperature gradient, together with mechanism to adapted extreme temperature by regulating the conformation transition of their DNA, protein, and specialized enzymes.