PNNL

Abstract

In oxygen-depleted soils, it is widely asserted that polyphenols inhibit microbial activity through cellular toxicity, substrate binding, and microbial enzyme inhibition, thus acting to “lock” soil carbon cycling. Here we used anoxic soil reactors amended with and without a chemically defined polyphenol to test this hypothesis, blending metabolomics and genome-resolved metaproteomics to interrogate microbial metabolism. Challenging the idea that polyphenols are not bioavailable under anoxia, this approach provided time-series metabolite and gene expression evidence for polyphenol depolymerization, resulting in monomer accumulation and catabolism, and further phenolic acid metabolism. Our findings also indicated that polyphenol amendment was not universally toxic, instead selectively stimulating a subset of microorganisms. Furthermore, this data provided a new view of microbial-polyphenol interactions, where these compounds did not restrict, but enhanced, overall soil carbon cycling. In all, our high-resolution multi-omics results demonstrated that soil microbiota subverted the polyphenol lock, sustaining carbon cycling in anoxic soils.