Cyanobacteria are model organisms for photosynthesis and are attractive for biotechnology applications. To aid investigation of genotype-phenotype relationships in cyanobacteria, we develop an inducible CRISPRi gene repression library in Synechocystis sp. PCC 6803, where we aim to target all genes for repression. We track the growth of all library members in multiple conditions and estimate gene fitness. The library reveals several clones with increased growth rates, and these have a common upregulation of genes related to cyclic electron flow. We challenge the library with 0.1 M L-lactate and find that repression of peroxiredoxin bcp2 increases growth rate by 49%. Transforming the library into an L-lactate-secreting Synechocystis strain and sorting top lactate producers enriches clones with sgRNAs targeting nutrient assimilation, central carbon metabolism, and cyclic electron flow. In many examples, productivity can be enhanced by repression of essential genes, which are difficult to access by transposon insertion.
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http://dx.doi.org/10.1038/s41467-020-15491-7 | DOI Listing |
Methods Mol Biol
December 2024
Systems, Synthetic, and Physical Biology Program, Rice University, Houston, TX, USA.
Optogenetics enables precise control of gene expression in a variety of organisms. We recently developed the first system for optogenetic control of transcription in Bacillus subtilis. This system is based on CcaSR, a light-responsive two-component regulatory system originally derived from Synechocystis PCC 6803.
View Article and Find Full Text PDFBiotechnol Bioeng
December 2024
School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona, USA.
Quantification of cyanobacterial CO fixation rates is vital to determining their potential as industrial strains in a circular bioeconomy. Currently, however, CO fixation rates are most often determined through indirect and/or low-resolution methods, resulting in an incomplete picture of both dynamic behaviors and total carbon fixation potential. To address this, we developed the "Automated Carbon and CO Experimental Sampling System" (ACCESS); a low-cost system for in situ off-gas analysis that supports the automated acquisition of high-resolution volumetric CO uptake rates from multiple cyanobacterial cultures in parallel.
View Article and Find Full Text PDFPhotosynth Res
February 2025
Department of Biology, Washington University, St. Louis, MO, 63130, USA.
Excitation energy transfer between the photochemically active protein complexes is key for photosynthetic processes. Phototrophic organisms like cyanobacteria experience subtle changes in irradiance under natural conditions. Such changes need adjustments to the excitation energy transfer between the photosystems for sustainable growth.
View Article and Find Full Text PDFFEBS J
December 2024
Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Germany.
The enzyme glucose-1-phosphate adenylyltransferase (GlgC, EC:2.7.7.
View Article and Find Full Text PDFBiotechnol Biofuels Bioprod
December 2024
Manchester Institute of Biotechnology and Department of Chemistry, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK.
Background: Cyanobacteria have long been suggested as an industrial chassis for the conversion of carbon dioxide to products as part of a circular bioeconomy. The slow growth, carbon fixation rates, and limits of carbon partitioning between biomass and product in cyanobacteria must be overcome to fully realise this industrial potential. Typically, flux towards heterologous pathways is limited by the availability of core metabolites.
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