1. Transcriptomic analysis reveals insights into the responses of Synechocystis sp. PCC 6803 to acidification during cultivation with ammonium salts as a nitrogen source.
- Author
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Kobayashi K, Yoneda K, Maeda Y, and Suzuki I
- Subjects
- Hydrogen-Ion Concentration, Photosynthesis drug effects, Transcriptome, Bacterial Proteins metabolism, Bacterial Proteins genetics, Culture Media chemistry, Synechocystis genetics, Synechocystis metabolism, Synechocystis growth & development, Synechocystis drug effects, Nitrogen metabolism, Ammonium Compounds metabolism, Gene Expression Regulation, Bacterial drug effects, Gene Expression Profiling
- Abstract
Utilizing ammonium in wastewater is a prospective way to reduce costs for bioproduction by photosynthetic organisms. A model cyanobacterium Synechocystis sp. PCC 6803 takes advantage of tolerance to ammonium compared to other microalgae. However, in this study, we report that Synechocystis growth was inhibited when cultured in a medium containing ammonium. This may be due to the pH decreasing below 6 caused by consuming ammonium. Transcriptomic analysis by RNA-seq revealed that the expression of the genes for proteases, chaperones, and antioxidant-scavenging enzymes was induced, but photosynthetic components were repressed. Although these regulations are similar to the previous studies on acidic stress in nitrate-containing culture, the expression of genes such as sigD, slr0042, slr0373, slr0374, and slr1501 was different, indicating that these phenomena are not simply identical to the known responses to acidic stress. The expression of the genes for photosynthesis, gluconeogenesis, and nitrogen assimilation was repressed, and glycolysis and the tricarboxylic acid cycle were induced. Despite the up-regulation of the carbon catabolism and down-regulation of nitrogen assimilation, the 2-oxoglutarate content in the ammonium-grown cells was lower than that in the nitrate-grown cells, and the contents of the major amino acids, such as Glu, Ala, Asp, and Gly were decreased, while the minor amino acids were the same or increased, especially Arg, Lys, Val, and Ile. These results demonstrated that the acidic stress induced by the consumption of ammonium ions differs from the sudden pH drop, and the Synechocystis cell manages amino acid levels to endure carbon limitation under the stress., (Copyright © 2024 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.)
- Published
- 2024
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