The transcriptional regulation of the glyoxylate cycle in SAR11 in response to iron fertilization in the Southern Ocean

• Published in: Environmental Microbiology Reports
• Main Authors: Beier, Sara, Galvez, Maria J, Molina, Veronica, Sarthou, Géraldine, Quéroué, Fabien, Blain, Stephane, Obernosterer, Ingrid
• Other Authors: Laboratoire d'Océanographie Microbienne (LOMIC), Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire océanologique de Banyuls (OOB), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Universidad de Concepción Chile, Universidad de Playa Ancha, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute for Marine and Antarctic Studies Horbat (IMAS), University of Tasmania Hobart, Australia (UTAS), Antarctic Climate and Ecosystems Cooperative Research Centre (ACE-CRC), ANR-10-BLAN-0614,KEOPS 2,Kerguelen : Comparaison plateau Ocean2(2010)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: PHYTOPLANKTON BLOOM; HETEROTROPHIC BACTERIA; GROWTH; BACTERIOPLANKTON; PROTEORHODOPSIN; METABOLISM; LIMITATION; GENOME; SEA; ACL; envir; socio; Southern Ocean
• Online Access: https://doi.org/10.1111/1758-2229.12267; https://hal.sorbonne-universite.fr/hal-01130266/file/Beier_2015_The_transcriptional.pdf; https://hal.sorbonne-universite.fr/hal-01130266

International audience The tricarboxylic acid (TCA) cycle is a central metabolic pathway that is present in all aerobic organisms and initiates the respiration of organic material. The glyoxylate cycle is a variation of the TCA cycle, where organic material is recycled for subsequent assimilation into cell material instead of being released as carbon dioxide. Despite the importance for the fate of organic matter, the environmental factors that induce the glyoxylate cycle in microbial communities remain poorly understood. In this study, we assessed the expression of isocitrate lyase, the enzyme that induces the switch to the glyoxylate cycle, of the ubiquitous SAR11 clade in response to natural iron fertilization in the Southern Ocean. The cell-specific transcriptional regulation of the glyoxylate cycle, as determined by the ratio between copy numbers of isocitrate lyase gene transcripts and isocitrate genes, was consistently lower in iron fertilized than in high-nutrient, low chlorophyll waters (by 2.4-to 16.5-fold). SAR11 cell-specific isocitrate lyase gene transcription was negatively correlated to chlorophyll a, and bulk bacterial heterotrophic metabolism. We conclude that the glyoxylate cycle is a metabolic strategy for SAR11 that is highly sensitive to the degree of iron and carbon limitation in the marine environment.