title: Active methylotrophs in the sediments of Lonar Lake, a saline and alkaline ecosystem formed by meteor impact.
abstract: Lonar Lake is a unique saline and alkaline ecosystem formed by meteor impact in the Deccan basalts in India around 52,000 years ago. To investigate the role of methylotrophy in the cycling of carbon in this unusual environment, stable-isotope probing (SIP) was carried out using the one-carbon compounds methane, methanol and methylamine. Denaturing gradient gel electrophoresis fingerprinting analyses performed with heavy (13)C-labelled DNA retrieved from sediment microcosms confirmed the enrichment and labelling of active methylotrophic communities. Clone libraries were constructed using PCR primers targeting 16S rRNA genes and functional genes. Methylomicrobium, Methylophaga and Bacillus spp. were identified as the predominant active methylotrophs in methane, methanol and methylamine SIP microcosms, respectively. Absence of mauA gene amplification in the methylamine SIP heavy fraction also indicated that methylamine metabolism in Lonar Lake sediments may not be mediated by the methylamine dehydrogenase enzyme pathway. Many gene sequences retrieved in this study were not affiliated with extant methanotrophs or methylotrophs. These sequences may represent hitherto uncharacterized novel methylotrophs or heterotrophic organisms that may have been cross-feeding on methylotrophic metabolites or biomass. This study represents an essential first step towards understanding the relevance of methylotrophy in the soda lake sediments of an unusual impact crater structure.
authors.affiliation: Microbial Culture Collection, National Centre for Cell Science, Pune, India.
authors.forename: Chakkiath Paul
authors.initials: CP
authors.lastname: Antony
authors.forename: Deepak
authors.initials: D
authors.lastname: Kumaresan
authors.forename: Lucia
authors.initials: L
authors.lastname: Ferrando
authors.forename: Rich
authors.initials: R
authors.lastname: Boden
authors.forename: Hélène
authors.initials: H
authors.lastname: Moussard
authors.forename: Ana Fernández
authors.initials: AF
authors.lastname: Scavino
authors.forename: Yogesh S
authors.initials: YS
authors.lastname: Shouche
authors.forename: J Colin
authors.initials: JC
authors.lastname: Murrell
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002247:Carbon Isotopes / Q000378:metabolism; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D017753:Ecosystem; D004591:Electrophoresis, Polyacrylamide Gel; D019015:Geologic Sediments / Q000382:microbiology*; D007194:India; D007553:Isotope Labeling; D054892:Metagenome; D019110:Meteoroids; D008697:Methane / Q000378:metabolism*; D000432:Methanol / Q000378:metabolism*; D008744:Methylamines / Q000378:metabolism*; D008969:Molecular Sequence Data; D009691:Nucleic Acid Denaturation; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D002247:Carbon Isotopes; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D008744:Methylamines; D012336:RNA, Ribosomal, 16S; C027451:methylamine; D008697:Methane; D000432:Methanol