Importance of substrate quality and clay content on microbial extracellular polymeric substances production and aggregate stability in soils

Abstract We investigated the effects of substrate (cellulose or starch) and different clay contents on production microbial extracellular polymeric substances (EPS) concomitant development stable soil aggregates. Soils were incubated with amounts montmorillonite (+ 0.1%, + 1%, 10%) both without two substrates contrasting quality (starch cellulose). Microbial respiration (CO 2 ), biomass carbon (C), EPS-protein, EPS-polysaccharide determined over experimental period. The diversity compositional shifts communities (bacteria/archaea) analysed by sequencing 16S rRNA gene fragments amplified from DNA. Soil aggregate size distribution was geometric mean diameter calculated for formation. Aggregate stabilities compared among 1–2-mm fraction. Starch amendment supported a faster increase than cellulose in biomass. community structure composition differed depending C added. However, addition had more pronounced effect alpha to starch cellulose. Substrate resulted an increased EPS concentration only if combined addition. At high addition, higher concentrations Where additional not provided, EPS-protein weakly correlated formation stability. relationship became stronger substrate. Labile organic thus clearly plays role formation, but increasing content found enhance stability additionally distinct production.