title: Astrobiological implications of dim light phototrophy in deep-sea red clays.
abstract: Red clays of Central Indian Basin (CIB) under influence of trace of Rodriguez Triple Junction exhibited chemoautotrophy, low temperature hydrothermal alterations and photoautotrophic potential. Seamount flank TVBC-08, hosting such signatures revealed dominance of aerobic anoxygenic phototroph Erythrobacter, with 93% of total 454 pyrosequencing tags. Subsequently, enrichments for both aerobic (Erythrobacter) and anaerobic anoxygenic phototrophs (green and purple sulphur bacteria) under red and white LED light illumination, with average irradiance 30.66Wm-2, were attempted for three red-clay sediment cores. Successful enrichments were obtained after incubation for c.a. 120 days at 4°± 2°C and 25°± 2°C, representing ambient psychrophilic and low temperature hydrothermal alteration conditions respectively. During hydrothermal cooling, a microbial succession from anaerobic chemolithotrophy to oxygenic photoautotrophy through anaerobic/aerobic anoxygenic phototrophic microbes is indicated. Spectral absorbance patterns of the methanol extracted cell pellets showed peaks corresponding to metal sulphide precipitations, the Soret band of chlorosome absorbance by photosystem II and absence of peaks at Qy transition band. Dendritic nano-structures of metal sulphides are common in these sediments and are comparable with other sulphidic paleo-marine Martian analogues. Significant blue and redshifts have been observed for the experimental samples relative to the un-inoculated medium. These observations indicate the propensity of metal-sulphide deposits contributing to chemiluminiscence supporting the growth of phototrophs at least partially, in the otherwise dark abyss. The effects of other geothermal heat and light sources are also under further consideration. The potential of phototrophic microbial cells to exhibit Doppler shift in absorbance patterns is significant towards understanding planetary microbial habitability. Planetary desiccation could considerably influence Doppler effects and consequently spectral detection techniques exo-planetary microbial life.
authors.affiliation: Agharkar Research Institute-Maharashtra Association for the Cultivation of Science (MACS), G.G. Agarkar Road, Pune-411004, Maharastra, India; Council of Scientific and Industrial Research-National Institute of Oceanography, Dona Paula-403004, Goa, India. Electronic address: anindita.ocean@gmail.com.
authors.forename: Anindita
authors.initials: A
authors.lastname: Das
authors.affiliation: Council of Scientific and Industrial Research-National Institute of Oceanography, Dona Paula-403004, Goa, India; Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, 3422 Sesoko, Motobu, Okinawa 905-0277, Japan.
authors.forename: Tanya
authors.initials: T
authors.lastname: Singh
authors.affiliation: Council of Scientific and Industrial Research-National Institute of Oceanography, Dona Paula-403004, Goa, India.
authors.forename: P A
authors.initials: PA
authors.lastname: LokaBharathi
authors.affiliation: Agharkar Research Institute-Maharashtra Association for the Cultivation of Science (MACS), G.G. Agarkar Road, Pune-411004, Maharastra, India.
authors.forename: Prashant K
authors.initials: PK
authors.lastname: Dhakephalkar
authors.affiliation: Agharkar Research Institute-Maharashtra Association for the Cultivation of Science (MACS), G.G. Agarkar Road, Pune-411004, Maharastra, India.
authors.forename: Sweta
authors.initials: S
authors.lastname: Mallik
authors.affiliation: Agharkar Research Institute-Maharashtra Association for the Cultivation of Science (MACS), G.G. Agarkar Road, Pune-411004, Maharastra, India.
authors.forename: Pranav R
authors.initials: PR
authors.lastname: Kshirsagar
authors.affiliation: Council of Scientific and Industrial Research-National Institute of Oceanography, Dona Paula-403004, Goa, India.
authors.forename: N H
authors.initials: NH
authors.lastname: Khadge
authors.affiliation: Council of Scientific and Industrial Research-National Institute of Oceanography, Dona Paula-403004, Goa, India.
authors.forename: B Nagender
authors.initials: BN
authors.lastname: Nath
authors.affiliation: Space Application Centre- Indian Space Research Organisation (SAC-ISRO), #4361, Satellite Road, Ambawadi Vistar P. O., Ahmedabad - 380 015, Gujarat, India.
authors.forename: Satadru
authors.initials: S
authors.lastname: Bhattacharya
authors.affiliation: Space Application Centre- Indian Space Research Organisation (SAC-ISRO), #4361, Satellite Road, Ambawadi Vistar P. O., Ahmedabad - 380 015, Gujarat, India.
authors.forename: Aditya Kumar
authors.initials: AK
authors.lastname: Dagar
authors.affiliation: Space Application Centre- Indian Space Research Organisation (SAC-ISRO), #4361, Satellite Road, Ambawadi Vistar P. O., Ahmedabad - 380 015, Gujarat, India.
authors.forename: Prabhjot
authors.initials: P
authors.lastname: Kaur
authors.affiliation: Physical Research Laboratory, Thaltej, Ahmedabad-380054, Gujrat, India.
authors.forename: Dwijesh
authors.initials: D
authors.lastname: Ray
authors.affiliation: Physical Research Laboratory, Thaltej, Ahmedabad-380054, Gujrat, India.
authors.forename: Anil D
authors.initials: AD
authors.lastname: Shukla
authors.affiliation: Council of Scientific and Industrial Research-National Institute of Oceanography, Dona Paula-403004, Goa, India.
authors.forename: Christabelle E G
authors.initials: CEG
authors.lastname: Fernandes
authors.affiliation: Council of Scientific and Industrial Research-National Institute of Oceanography, Dona Paula-403004, Goa, India; National Centre for Antarctic and Ocean Research, Headland Sada, Vasco-da-Gama 403804, Goa, India.
authors.forename: Sheryl O
authors.initials: SO
authors.lastname: Fernandes
authors.affiliation: Council of Scientific and Industrial Research-National Institute of Oceanography, Dona Paula-403004, Goa, India.
authors.forename: Tresa Remya A
authors.initials: TRA
authors.lastname: Thomas
authors.affiliation: Council of Scientific and Industrial Research-National Institute of Oceanography, Dona Paula-403004, Goa, India.
authors.forename: Mamatha
authors.initials: M
authors.lastname: S S
authors.affiliation: Council of Scientific and Industrial Research-National Institute of Oceanography, Dona Paula-403004, Goa, India.
authors.forename: Babu Shashikant
authors.initials: BS
authors.lastname: Mourya
authors.affiliation: Council of Scientific and Industrial Research-National Institute of Oceanography, Dona Paula-403004, Goa, India.
authors.forename: Ram Murti
authors.initials: RM
authors.lastname: Meena
mesh_terms: D000538:Aluminum Silicates / Q000528:radiation effects*; D001419:Bacteria / Q000378:metabolism*; D000077215:Clay; D018559:Exobiology; D008027:Light; D009792:Oceans and Seas; D010788:Photosynthesis / Q000528:radiation effects*; D052817:Phototrophic Processes; D013440:Sulfides / Q000737:chemistry; D014871:Water Microbiology
chemical_list: D000538:Aluminum Silicates; D013440:Sulfides; D000077215:Clay
keywords: Aerobic; Anaerobic; Anoxygenic phototrophs; Astrobiology; Central India Basin; Dim-light phototrophy