Nature Communications (May 2024)

Alpha-glucans from bacterial necromass indicate an intra-population loop within the marine carbon cycle

  • Irena Beidler,
  • Nicola Steinke,
  • Tim Schulze,
  • Chandni Sidhu,
  • Daniel Bartosik,
  • Marie-Katherin Zühlke,
  • Laura Torres Martin,
  • Joris Krull,
  • Theresa Dutschei,
  • Borja Ferrero-Bordera,
  • Julia Rielicke,
  • Vaikhari Kale,
  • Thomas Sura,
  • Anke Trautwein-Schult,
  • Inga V. Kirstein,
  • Karen H. Wiltshire,
  • Hanno Teeling,
  • Dörte Becher,
  • Mia Maria Bengtsson,
  • Jan-Hendrik Hehemann,
  • Uwe. T. Bornscheuer,
  • Rudolf I. Amann,
  • Thomas Schweder

DOI
https://doi.org/10.1038/s41467-024-48301-5
Journal volume & issue
Vol. 15, no. 1
pp. 1 – 15

Abstract

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Abstract Phytoplankton blooms provoke bacterioplankton blooms, from which bacterial biomass (necromass) is released via increased zooplankton grazing and viral lysis. While bacterial consumption of algal biomass during blooms is well-studied, little is known about the concurrent recycling of these substantial amounts of bacterial necromass. We demonstrate that bacterial biomass, such as bacterial alpha-glucan storage polysaccharides, generated from the consumption of algal organic matter, is reused and thus itself a major bacterial carbon source in vitro and during a diatom-dominated bloom. We highlight conserved enzymes and binding proteins of dominant bloom-responder clades that are presumably involved in the recycling of bacterial alpha-glucan by members of the bacterial community. We furthermore demonstrate that the corresponding protein machineries can be specifically induced by extracted alpha-glucan-rich bacterial polysaccharide extracts. This recycling of bacterial necromass likely constitutes a large-scale intra-population energy conservation mechanism that keeps substantial amounts of carbon in a dedicated part of the microbial loop.