Important ecophysiological roles of non-dominant Actinobacteria in plant residue decomposition, especially in less fertile soils

Abstract Background Microbial-driven decomposition of plant residues is integral to carbon sequestration in terrestrial ecosystems. Actinobacteria , one the most widely distributed bacterial phyla soils, are known for their ability degrade vitro. However, situ importance and specific activity across contrasting ecological environments not known. Here, we conducted three field experiments with buried straw combination microcosm 13 C-straw paddy soils under different soil fertility levels reveal ecophysiological roles residue decomposition. Results While accounting only 4.6% total abundance, encoded 16% abundance carbohydrate-active enzymes (CAZymes). The taxonomic functional compositions were, surprisingly, relatively stable during Slopes linear regression models between chemical composition Actinobacterial traits were flatter than those other groups at both local regional scales due holding genes encoding full set CAZymes, nitrogenases, antibiotic synthetases. Ecological co-occurrence network C-based metagenomic analyses indicated that degradation increased less fertile as links community members relative abundances decreasing fertility. Conclusions This study provided DNA-based evidence non-dominant plays a key role possess high proportions CAZymes group maintain presence terms roles. Their was more pronounced where possession interspecies interactions stood out more. Our work provides new angles understanding global cycling.