Speleothems from Mawsmai and Krem Phyllut caves,Meghalaya, India: some evidences on biogenic activities |
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| Authors: | Sushmitha Baskar R Baskar Natuschka Lee P K Theophilus |
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| Institution: | (1) Department of Environmental Science and Engineering, Guru Jambheshwar University of Science and Technology, Hisar, 125001, Haryana, India;(2) Division Microbial Systems Ecology (MSE), Department of Microbiology, Technical University of Munich (TUM), Am Hochanger 4, 85354 Freising, Germany |
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| Abstract: | The Mawsmai cave and Krem Phyllut caves, East Khasi hills, Meghalaya, India has so far not yet attracted the attention of
geomicrobiologists. Observations and hypotheses on the possible influence of identified microorganisms for speleothem formations
in Meghalaya are reported for the first time. XRD studies identified calcite in speleothems and gypsum in cave wall deposits
as the dominant minerals. SEM-EDAX showed interesting microfabric features showing strong resemblance with fossilised bacteria,
calcified filaments, needle calcite and numerous nano scale calcite crystals, highly weathered and disintegrated crystals
of calcite, that point towards a significant microbial influence in its genesis. Thin section petrography showed laminated
stromatolitic features. The microorganisms identified by conventional isolation and further evaluation of isolates by molecular
techniques include Bacillus cereus, Bacillus mycoides, Bacillus licheniformis, Micrococcus luteus, and Actinomycetes. Microscopic observations also showed unidentifiable cocci and four unidentifiable strains of CaSO4 (gypsum) precipitating bacteria. Experimental studies confirmed that these bacteria are able to precipitate calcium minerals
(calcite, gypsum, minor amounts of dolomite) in the laboratory. These results allow us to postulate that species like these
may contribute to active biogenic influence in the cave formations at Meghalaya. |
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| Keywords: | Geomicrobiology Caves Carbonate speleothems Calcium minerals Biogeochemistry Bacteria |
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