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Cyanobacteria are the only prokaryotes performing oxygenic photosynthesis. Non-diazotrophic strains such as the model Synechocystis sp. PCC 6803 depend on a balanced uptake and assimilation of inorganic carbon and nitrogen sources. The internal C/N ratio is sensed via the PII protein (GlnB). We analyzed metabolic changes of the DglnB mutant of Synechocystis sp. PCC 6803 under different CO2 availability. The identified metabolites provided a snapshot of the central C/N metabolism. Cells of the DglnB mutant shifted to carbon-limiting conditions, i.e. a decreased C/N ratio, showed changes in intermediates of the sugar storage and particularly of the tricarboxylic acid cycle, arginine, and glutamate metabolism. The changes of the metabolome support the notion that the PII protein is primarily regulating the N-metabolism whereas the changes in C-metabolism are probably secondary effects of the PII deletion.
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http://dx.doi.org/10.3390/metabo4020232 | DOI Listing |
ISME J
September 2025
Department of Ecology, Environment and Plant Sciences, Stockholm University, Svante Arrhenius väg 20A, SE-106 91 Stockholm, Sweden.
Symbioses between diatoms and the N2-fixing, heterocyst-forming cyanobacterium Richelia spp. are widespread and contribute to primary production. Unique to these symbioses is a variation in the symbiont location: one lives in the host cytoplasm (endobiont) vs.
View Article and Find Full Text PDFACS Synth Biol
September 2025
Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development (CNPD3), University of Florida, Gainesville, Florida 32610, United States.
Heterologous expression of biosynthetic gene clusters (BGCs) is a powerful strategy for natural product (NP) discovery, yet achieving consistent expression across microbial hosts remains challenging. Here, we developed cross-phyla vector systems enabling the expression of BGCs from cyanobacteria and other bacterial origins in Gram-negative , Gram-positive , and two model cyanobacterial strains including unicellular PCC 6803 and filamentous sp. PCC 7120.
View Article and Find Full Text PDFMicrob Cell Fact
August 2025
Molecular Plant Biology Unit, Department of Life Technologies, University of Turku, Turku, Finland.
Cyanobacteria are emerging as a promising platform for whole-cell biotransformation, harnessing solar energy to drive biocatalytic reactions through recombinant enzymes. However, optimisation remains challenging due to the complexity of the cyanobacterial metabolism and the regulatory framework in which heterologous enzymes operate. While many enzymes have been deployed for light-driven whole-cell biotransformations, the different experimental conditions used between studies make direct comparison and systematic improvement difficult.
View Article and Find Full Text PDFBioresour Technol
August 2025
Helmholtz Center for Environmental Research (UFZ) Leipzig, Permoserstraße 15, D-04318, Germany.
Photosynthetic efficiency (PE) is key to evaluating phototrophic organisms in biotechnological applications. However, current methods offer limited, indirect insights with poor time resolution. To address this, photo-calorespirometry (Photo-CR) was developed, a novel, non-invasive technique for real-time, direct quantification of photosynthetic energy conversion.
View Article and Find Full Text PDFPlant Physiol Biochem
August 2025
Institute of Plant Biology, HUN-REN Biological Research Centre, Szeged, Temesvári krt. 62, H-6726, Szeged, Hungary. Electronic address:
Carotenoid biosynthesis in photosynthetic organisms involves converting cis-isomers to trans forms through enzymatic and light-induced reactions. While enzymatic pathways are well-documented, the role of light, particularly chlorophyll-mediated sensitization, remains unclear. This gap in understanding complicates efforts to optimize carotenoid production and fully grasp the evolutionary interplay between enzymatic and light-driven processes.
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