Pattern of Elemental Release During the Granite Dissolution Can Be Changed by Aerobic Heterotrophic Bacterial Strains Isolated from Damma Glacier (Central Alps) Deglaciated Granite Sand

Abstract

Colonisation and weathering of freshly deglaciated granite are key processes in initial soil formation and development. We have obtained 438 isolates from granite sand covering glacial toe, 284 isolates at 22°C and 154 at 4°C incubation temperatures, respectively, to obtain cultures for the investigation of their weathering capabilities under laboratory conditions. The isolation of bacteria from granite sand was performed on rich-, intermediate- and low-nutrient-content solid media. Isolates were identified by 16S rRNA gene sequencing. According to the genera-associated weathering capabilities described in the literature and according to their abundance in our culture collection, we selected eight strains to analyse their effects on the weathering dynamics of granite sand during the batch culture experiment. Analysis of culturable bacteria showed higher species richness among isolates from 22°C than from 4°C incubations. In the R2A and 1/100 Ravan media, we observed the highest species richness of isolates obtained at 22°C and 4°C incubation temperatures, respectively. The obtained 16S rRNA sequences revealed the presence of alpha-, beta- and gamma-proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. The most numerous group of isolates was distantly related to Collimonas representatives, and according to the sequences of the 16S rRNA genes, they can form a new genus. Isolates from this group had the capability of causing increased dissolution rates for Fe, W, Ni and Rb. In general, at each sampling during the 30-day experiment, every strain showed a unique weathering profile resulting from differential rates of the dissolution and the precipitation of different minerals in the batch culture. Consequently, the presence of different strains, their growth stage and changes in proportions of strains in the bacterial community can affect further soil development and the successive colonisation by plants.

Mineral Types and Tree Species Determine the Functional and Taxonomic Structures of Forest Soil Bacterial Communities

“…In contrast, representatives of Bacteroidetes, Actinobacteria, and Proteobacteria were significantly enriched in our study for all mineral types considered. Notably, these taxa have been repeatedly detected on mineral or rock surfaces such as granite, volcanic basaltic glass, marine basalts, or pure particles of apatite (33,(46)(47)(48), indicating that they may be adapted to colonize and inhabit rock and mineral surfaces in terrestrial and aquatic ecosystems.…”

Correlation of the Abundance of Betaproteobacteria on Mineral Surfaces with Mineral Weathering in Forest Soils

“…To date, the ability to weather minerals has been demonstrated for a large range of bacterial strains isolated from various environments such as the rhizosphere of several plants (10,32,39,49) and granite samples from the Damma glacier (19,30). This ability was notably reported for bacteria belonging to the Arthrobacter, Bacillus, Burkholderia, and Collimonas genera (3,19,33,46,51,56,57).…”

“…Due to their nutritive value, minerals can be considered a true ecological habitat giving excellent physical support for the development of specific microbial communities (8,11,12,21,30,43,54). As an example, Gleeson et al (21) demonstrated that the taxonomic structure of the bacterial communities colonizing granite minerals was not homogenous and varied in relation with the mineral crystals (muscovite, plagioclase, K-feldspar, and quartz) present in this granite.…”

The role of microorganisms at different stages of ecosystem development for soil formation

“…This was investigated in mineral dissolution experiments using bacterial isolates from the Damma forefield (Lapanje et al, 2012). Selected isolates were screened for high mineral dissolution potential; however, the abiotic controls using citric and hydrochloric acid released elements at significantly higher rates than the bacterial isolates did (Lapanje et al, 2012). Future studies need to investigate the P release from mineral bedrock in the initial soils, as the mechanisms have not been studied in detail, but are crucial for the development of the ecosystem.…”

“…The dissolution of P and other nutrients from the minerals might be accelerated by microorganisms releasing organic acids or chelators. This was investigated in mineral dissolution experiments using bacterial isolates from the Damma forefield (Lapanje et al, 2012). Selected isolates were screened for high mineral dissolution potential; however, the abiotic controls using citric and hydrochloric acid released elements at significantly higher rates than the bacterial isolates did (Lapanje et al, 2012).…”