The structure of microbial communities in redoximorphic microsites of Gleysol

The community composition of soil prokaryotes and micro-eukaryotes in redoximorphic microsites of highly heterogeneous Gleysol were studied at a mm scale by 16S and 18S amplicon sequencing after DNA extraction based on microwave rupture with SDS lysis solution. Results were compared with communities recovered from standard 250 mg mixed samples treated by bead-beating DNA extraction. Analysis of distances between communities was performed to test if adjacent samples were closer to each other than randomly selected ones, and if microbial communities reflected ferric-ferrous patchiness in gley horizons. The reduction of soil sample size till mm level allowed to reveal the part of community unseen using the standard technique (21-39% of all prokaryotic and 28-60% of all micro-eukaryotic operational taxonomic units revealed by both methods was seen uniquely in micro-samples). The agreement of patchiness of ferric mottles with patchiness of microbial communities was revealed in Bg2 gley horizon. Ferric mottles were significantly enriched with total P and Fe and depleted with O, Si, Al, K and Ca compared with groundmass there, and both prokaryotic and micro-eukaryotic communities were significantly different between mottles and groundmass.