The transcriptional regulation of the glyoxylate cycle in SAR11 in response to iron fertilization in the Southern Ocean
journal contribution
posted on 2023-05-18, 16:04authored byBeier, S, Galvez, MJ, Molina, V, Sarthou, G, Queroue, F, Blain, S, Obernosterer, I
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.
History
Publication title
Environmental Microbiology Reports
Volume
7
Pagination
427-434
ISSN
1758-2229
Department/School
Institute for Marine and Antarctic Studies
Publisher
Wiley-Blackwell Publishing Ltd.
Place of publication
United Kingdom
Rights statement
Copyright 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.
Repository Status
Restricted
Socio-economic Objectives
Measurement and assessment of marine water quality and condition