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Microbial biomass turnover times and clues to cellular protein repair in energy-limited deep Baltic Sea sediments

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  • Snehit S Mhatre, Syddansk Universitet
  • ,
  • Stefan Kaufmann
  • ,
  • Ian P G Marshall
  • Stephen Obrochta, Graduate School of International Resource Sciences, Department of Earth Resource Science, Akita University, 1-1 Tegatagakuen-machi, Akita City 010-8502, Japan.
  • ,
  • Thomas Andrèn, School of Natural Sciences, Technology and Environmental Studies, Södertörn University, Alfred Nobels all 7, Flemingsberg, 14189 Huddinge, Sweden.
  • ,
  • Bo Barker Jørgensen
  • Bente Aa Lomstein

The discovery of active microbial life deeply buried beneath the seafloor has opened important questions: how do microorganisms cope with extreme energy limitation, what is their metabolic activity, and how do they repair damages to essential biomolecules? We used a D:L-amino acid model to calculate microbial biomass turnover times. We used a metagenome and metatranscriptome analysis to investigate the distribution of the gene that encodes Protein-L-iso aspartate(D-aspartate) O-methyltransferase (PCMT), an enzyme which recognizes damaged L-isoapartyl and D-aspartyl residues in proteins and catalyzes their repair. Sediment was retrieved during the Integrated Ocean Drilling Program (IODP) Expedition 347 from Landsort Deep and the Little Belt in the Baltic Sea. The study covers the period from the Baltic Ice Lake ca. 13 000 years ago to the present. Our results provide new knowledge on microbial biomass turnover times and protein repair in relation to different regimes of organic matter input. For the first time, we show that the PCMT gene was widely distributed and expressed among phylogenetically diverse groups of microorganisms. Our findings suggest that microbial communities are capable of repairing D-amino acids within proteins using energy obtained from the degradation of a mixture of labile compounds in microbial necromass and more recalcitrant organic matter.

TidsskriftFEMS Microbiology Ecology
StatusUdgivet - 1 jun. 2019

Bibliografisk note

© FEMS 2019.

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