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2951817 
Journal Article 
Weathering-associated bacteria from the Damma glacier forefield: physiological capabilities and impact on granite dissolution 
Frey, B; Rieder, SR; Brunner, I; Plötze, M; Koetzsch, S; Lapanje, A; Brandl, H; Furrer, G 
2010 
Yes 
Applied and Environmental Microbiology
ISSN: 0099-2240
EISSN: 1098-5336 
76 
14 
4788-4796 
English 
20525872 
Several bacterial strains isolated from granitic rock material in front of the Damma glacier (Central Swiss Alps) were shown (i) to grow in the presence of granite powder and a glucose-NH(4)Cl minimal medium without additional macro- or micronutrients and (ii) to produce weathering-associated agents. 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.