High temperature shock threatens methane production via disturbing microbial interactions in anaerobic digestion.

Operational strategies shape microbial interactions determining anaerobic digesting process, but it is unclear whether and how the microbial network properties impact gas generation, especially in the transitional stage after operations. This research examined how the high temperature shock affected microbial diversity and network traits connected with the biogas production in a swine manure-fed anaerobic digester. Rising temperature (from 35 °C to 50 °C) significantly reduced biogas and methane production (p < 0.001) in the transitional stage due to the syntrophic loss of Methanomicrobiaceae and Firmicutes affiliated families. The high temperature shock reduced network modularity and thus caused the system functioning loss. Furthermore, the methanogenic stability was disrupted by high temperature shock (reduced the abundance of Methanosphaera but increased the abundance of Methanoculleus), which may result in the subsequent dysbiosis with other syntrophic communities. These findings suggest that the increased temperature-induced high network complexity and stability, but microbial communities need more time to restore the microenvironment via establishing the interactions of keystone species.