Implications of Microbial Thiosulfate Utilization in Red Clay Sediments of the Central Indian Basin: The Martian Analogy

• Published in: Geochemistry, geophysics, geosystems : G3 geophysics, geosystems : G3, 2019-02, Vol.20 (2), p.708-729
• Main Authors: Singh, Tanya, Kshirsagar, Pranav R., Das, Anindita, Yadav, Kunal, Mallik, Sweta, Mascarenhas‐Pereira, M. B. L., Thomas, Tresa Remya A., Shivaramu, Mamatha S., P. A., LokaBharathi, Khadge, N. H., Nath, B. Nagender, Dhakephalkar, Prashant K., Iyer, Sridhar D., Ray, Dwijesh, Valsangkar, A. B., Garg, Anita, Prakash Babu, C., Waghole, Ravindra J., Waghmare, Shailesh S., Rajwade, Jyutika M., Paknikar, Kishore M.
• Format: Article
• Language: English
• Subjects: analogue; Central Indian Basin; Clay; Desiccation; Earth; Fracture zones; Iron; Mars; Mars surface sediments; Metabolism; microbe; Ocean floor; Oxidation; Pelagic clay; Sediment; Sediments; Sulfates; Sulfur; sulfur‐disproportionation; Sulphur; thiosulfate; Volcanism
• ISSN: 1525-2027; 1525-2027
• DOI: 10.1029/2018GC007640

Microbial thiosulfate utilization and S‐disproportionation could be important mechanisms of sulfate‐formations on Earth and Mars. Sulfates on Mars date back to late‐Noachian to Hesperian period. In contrast, the large sulfur/sulfate formations on Earth evolved under different chronological sequences. The S‐cycle was provoked intermittently, permitting multiple appearances of the S‐oxidizers on an evolutionary timescale. Hydrothermally altered deep‐oceanic red clay sediments of the Central Indian Basin were examined as potential analogue for sulfur (S) oxidation on Mars. The basin sediments supported an active microbial S‐metabolism that exhibited S‐disproportionation coupled to microbial carbon‐fixation through intermediate processes like thiosulfate utilization. Sulfur‐oxidizers/thiotrophic denitrifiers were isolated in large numbers at circum‐neutral pH, from these cold and dark abyssal Fe‐oxide dominated organic‐C starved clay. Experimental simulations under psychrophilic and thermo‐tolerant conditions revealed the coexistence of an anaerobic, thermal component under the predominantly oxic, circum‐neutral seafloor conditions. Multiple causative factors like hydrothermal seafloor circulation, in situ volcanism, and fracture zone reactivation could drive the widespread S‐cycle activity in the Central Indian Basin, albeit at a low scale. It is postulated that these conditions are analogous to Great Oxidation Event situations on Earth, when S‐oxidizers evolved and flourished. Experimental studies on microbial thiosulfate flux are few in spite of intense scientific interest in microbial S‐disproportionation. To the best of our knowledge, this is a new report on regression model development for microbial thiosulfate flux. These clay‐systems and their component microbes could serve as analogue to the ancient well‐hydrated Noachian Mars and throw light on planetary hydration and desiccation mechanisms. Key Points Hydrothermally altered deep‐sea red clay of Central Indian Basin (CIB) were examined as potential analogue for sulfur (S) oxidation on Mars An active microbial S‐disproportionation metabolism coupled to C‐fixation via intermediates like thiosulfate utilization was observed This is a new report on regression model development for microbial thiosulfate flux. These clays are analogous to the hydrated Noachian Mars