Bacterial colonization of minerals in grassland soils is selective and highly dynamic

Abstract

Summary Bacteria colonize reactive minerals in soils where they contribute to mineral weathering and transformation. So far, the specificity, patterns and dynamics of mineral colonization have rarely been assessed under natural conditions. High throughput Illumina sequencing was employed to investigate the bacterial communities assembling on illite and goethite during exposure to natural grassland soils. Two different types of organic carbon sources, simple carbon compounds representing root exudates and detritus of two dominant grassland plant species were applied, and their effects on the temporal dynamics of bacterial communities were investigated. The observed temporal patterns suggest that the surfaces of de novo exposed minerals in soils drive the establishment of bacterial communities and override the effect of the type of carbon sources and of other environmental properties. Mineral colonization was selective and specific bacterial sequence variants exhibited distinct colonization patterns, among which early, intermittent, and late colonizers could be distinguished. Based on our results, soil minerals are not only colonized by specific bacterial communities but enable a succession of different bacterial communities. Our results thereby expand the concept of the mineralosphere and provide novel insights into mechanisms of community assembly in the soil ecosystem.

High soilpHenhances the network interactions among bacterial and archaeal microbiota in alpine grasslands of the Tibetan Plateau

“…In this context, the co‐occurrence network for the soil microbiota was more stable in alpine grassland soils with a neutral pH than in acidic or alkaline soils. Numerous researches have suggested that ‘acidity specialists’ habitat in acidic soils and ‘alkalinity specialists’ in alkaline soils (Jones and Bennett, 2017; Vieira et al ., 2020). Among the low‐pH cluster microbial taxa that we detected, Bradyrhizobium species had been shown to favour low‐pH environments (Bottomley et al ., 1991; Graham et al ., 1994); and Nitrososphaera species from the high‐pH cluster, favours high‐pH environments (Zhalnina et al ., 2012).…”

The mineralosphere—interactive zone of microbial colonization and carbon use in grassland soils

“…The most labile C components in rhizodeposition are root exudates (Grayston et al 1997), which consist predominantly of sugars, amino acids, and organic acids (van Hees et al 2005). They are known to increase soil microbial activity and abundance and to affect microbial community composition (Grayston et al 1997;Rovira 1969;Strickland et al 2015;Vieira et al 2020). Glucose, glycine, and oxalic and citric acids have frequently been used to study the microbial response after addition of artificial root exudates (Eilers et al 2010;Strickland et al 2015).…”

“…Our approach exposed organo-mineral complexes, represented by pristine minerals loaded with ARE, in mineral containers in the topsoil of ten grassland sites of different land-use intensities of the Biodiversity Exploratories at the Schwäbische Alb (south-west Germany). Whereas Vieira et al (2020) used the same experimental set-up as the present study to describe bacterial community succession during one season, we present high-resolution temporal data on both the succession of organic compounds associated with minerals and of bacterial and fungal C use dynamics over one growth season. Specifically, we hypothesized that (1) the mineral-associated organic matter will be modified by colonizing microorganisms and/or by the input of soil-derived DOC;…”

Airborne bacterial emission fluxes from manure‐fertilized agricultural soil

“…For determination of total bacterial counts, an aliquot of each sample was fixed in 1% glutardialdehyde and stored at 4°C until analysis. Samples were stained with SYBR Green and filtered onto black 0.2 µm isopore membrane filters (Merck Millipore, Darmstadt, Germany) (Vieira et al ., 2019). Filters were placed between object slide and coverslip and sealed with nail polish, and images were monitored employing a Nikon Eclipse Ti inverted microscope with GFP (485/20‐525/30) filters.…”