Fig. 7

Schematic diagram of exogenous bacteria (“bioredox trigger”) modulating lithospheric indigenous microbial communities and element cycling. The early primary reservoirs (May, June) were primarily dominated by Proteobacteria and Firmicutes where electron acceptors were deficient. Our strategy of exogenous single-species manipulation was implemented in July by injecting heterocycle-degrader Pseudomonas strains into the subsurface. The N/S elements were in situ released and transformed to replenish extremely scarce electron acceptors in the lithosphere, activating the lithospheric N/S cycling and inducing microbial community succession (after Aug)