Weathering-Associated Bacteria from the Damma Glacier Forefield: Physiological Capabilities and Impact on Granite Dissolution

Abstract

. In particular, four bacterial isolates (one isolate each of Arthrobacter sp., Janthinobacterium sp., Leifsonia sp., and Polaromonas sp.) were weathering associated. In comparison to what was observed in abiotic experiments, the presence of these strains caused a significant increase of granite dissolution (as measured by the release of Fe, Ca, K, Mg, and Mn). These most promising weathering-associated bacterial species exhibited four main features rendering them more efficient in mineral dissolution than the other investigated isolates: (i) a major part of their bacterial cells was attached to the granite surfaces and not suspended in solution, (ii) they secreted the largest amounts of oxalic acid, (iii) they lowered the pH of the solution, and (iv) they formed significant amounts of HCN. As far as we know, this is the first report showing that the combined action of oxalic acid and HCN appears to be associated with enhanced elemental release from granite, in particular of Fe. This suggests that extensive microbial colonization of the granite surfaces could play a crucial role in the initial soil formation in previously glaciated mountain areas.

Potential sources of microbial colonizers in an initial soil ecosystem after retreat of an alpine glacier

“…They also represent ideal ecosystems to study natural establishment of microbial communities in terrestrial environments (Edwards et al, 2014). When glacier ice melts, entrapped rocks, sediments and fine debris are released and microbial pioneers present on these debris initiate soil formation by weathering rock minerals and incorporating organic matter (Frey et al, 2010;Smittenberg et al, 2012).…”

Microbial community changes along the Ecology Glacier ablation zone (King George Island, Antarctica)

“…Total nitrogen, phosphorus, and iron levels were however considerably higher (on average 4, 3, and 8 times, respectively). The higher macro and micronutrient levels may be attributed to physical and chemical weathering of the cryoconite sediment, but also to microbial activity like nitrogen fixation (Telling et al 2011) and bioleaching of insoluble mineral compounds (Frey et al 2010), especially iron containing minerals (Bashan et al 2013). The slightly elevated PO 4 3-and Ca 2?…”

Culturable bacteria community development in postglacial soils of Ecology Glacier, King George Island, Antarctica

“…In this respect, the bioleaching properties of Leifsonia spp. have been widely recognized (Hansen et al 2007;Delvasto et al 2008;Frey et al 2010).…”