Unraveling the roles of coastal bacterial consortia in degradation of various lignocellulosic substrates

<p>Lignocellulose, as the abundant natural organic carbon on earth, plays a key role in regulating the global carbon cycle, but there are only&nbsp;few studies in marine ecosystems. Little information is available&nbsp;about the extant lignin-degrading bacteria in coastal wetlands, limiting our understanding of their ecological roles and traits in lignocellulose degradation. We utilized<em>&nbsp;in situ </em>lignocellulose enrichment experiments coupled with 16S rRNA amplicon and shotgun metagenomics sequencing to identify and characterize bacterial consortia attributed to different lignin/lignocellulosic&nbsp;substrates in the southern-east intertidal zone of East China Sea.&nbsp;We found the consortia enriched on woody lignocellulose showed higher diversity than those on&nbsp;the herbaceous substrate. The substrate-dependent taxonomic&nbsp;groups were, hence, revealed.&nbsp;A time-dissimilarity&nbsp;pattern with increased alpha diversity over time was observed. Additionally, this study showed a comprehensive set of genes associated with lignin degradation potential,&nbsp;containing 23 gene families involved in lignin depolymerization, and 371 gene families involved in aerobic/anaerobic lignin-derived aromatic compound pathways, challenging the traditional&nbsp;view of lignin stability within marine ecosystems. In contrast to similar cellulase genes among the lignocellulose substrates, the significantly different ligninolytic&nbsp;gene groups were observed between consortia under woody and herbaceous&nbsp;substrates. Importantly, we not only observed synergistic degradation of lignin and hemi-/cellulose, but also pinpointed the potential biological actors at the levels of taxa and functional genes, which indicates&nbsp;that the alternation of aerobic and anaerobic&nbsp;catabolism could facilitate lignocellulose degradation. Our study advances the understanding of coastal bacterial community assembly and metabolic potential for lignocellulose substrates.</p>