Multi-omic data integration elucidates Synechococcus adaptation mechanisms to fluctuations in light intensity and salinity

Synechococcus sp. PCC 7002 is a fast-growing cyanobacterium which flourishes in freshwater and marine environments, owing to its ability to tolerate high light intensity and a wide range of salinities. Harnessing the properties of cyanobacteria and understanding their metabolic efficiency has become an imperative goal in recent years owing to their potential to serve as biocatalysts for the production of renewable biofuels. To improve characterisation of metabolic networks, genome-scale models of metabolism can be integrated with multi-omic data to provide a more accurate representation of metabolic capability and refine phenotypic predictions. In this work, a heuristic pipeline is constructed for analysing a genome-scale metabolic model of Synechococcus sp. PCC 7002, which utilises flux balance analysis across multiple layers to observe flux response between conditions across four key pathways. Across various conditions, the detection of significant patterns and mechanisms to cope with fluctuations in light intensity and salinity provides insights into the maintenance of metabolic efficiency

Recent advances in engineering fast-growing cyanobacterial species for enhanced CO2 fixation

Atmospheric CO2 removal (CDR) is a fundamentally endergonic process. Performing CDR or Bioenergy with Carbon Capture and Storage (BECCS) at the gigatonne scale will produce a significant additional burden on the planet’s limited renewable energy resources irrespective of the technology employed. Harnessing photosynthesis to drive industrial-scale CO2 fixation has been of significant interest because of its minimal energy requirements and potential low costs. In this review, we evaluated the thermodynamic considerations of performing atmospheric carbon removal using microalgae and cyanobacteria versus physicochemical processes and explore the implications of these energetic costs on the scalability of each respective solution. We review the biomass productivities of recently discovered fast-growing cyanobacterial strains and discuss the prospects of genetically engineering certain metabolic pathways for channeling the fixed carbon into metabolic ‘carbon sinks’ to further enhance their CO2 capture while concurrently extracting value. We share our perspectives on how new highly productive chassis strains combined with advanced flux balance models, essentially coupling synthetic biology with industrial biotechnology, may unlock more favorable methods for CDR, both from an economic and thermodynamic perspective

Ecophysiological Investigation of the Cyanobacterium Synechococcus for Potential Biomedical Application

Cyanobacteria are important primary producers in marine and other aqueous ecosystems. Members of the genus Synechococcus are globally distributed and exhibit high potential for acclimatisation and adaptation to diverse environmental conditions. The inter-disciplinary research project Endosymbiont (University of Bremen) proposes to utilize Synechococcus for the establishment of novel biomedical therapies based upon survival and growth under human physiological conditions. The main objective of the project is to successfully introduce living cyanobacterial cells into human keratinocytes (epidermal skin cells) in a quasi-stable functional coexistence. Such photosynthetic, endosymbiotic cells would then be able to produce oxygen and consequently promote wound healing in tissues with impaired perfusion. In this work, one marine and one freshwater strain of Synechococcus were characterised with respect to their short-term growth and tolerance to different culturing conditions,such as temperature, pH and salinity ranges mimicking certain aspects of the cytosol of human keratinocytes. The marine strain Synechococcus sp. RCC2384 (Red Sea) was not able to grow at salinities lower than 100% of the artificial seawater medium. The freshwater strain Synechococcus sp. PCC7942 showed sufficient tolerance to selected osmotic conditions, with growth rates between 2.4 ± 0.64 day-1 (0% salinity), 1.7 ± 0.23 (10%),2.6 ± 0.51 (20%) and 0.84 ± 0.3 day-1 (30%) during initial exponential growth at 30 °C. The pH that the medium was initially adjusted to had no effect on the actual pH measured in the cultures presumably due to the reduced carbonate buffer system in medium of lower salinity. However, the pH at time t0 had significant effects on the subsequent growth rates (t0 – t1), and the pigment signal strength at t1. This indicated a pH sensitivity regarding growth and physiological health that could not be fully evaluated for targeted pH values in this work. Nevertheless, a more acidic pH at t0 led to higher growth rates and lower pigment fluorescence when normalised to cell concentrations. The osmotic condition likely had an indirect effect on both parameters by widening the possible pH range. Due to the adaptability shown here for Synechococcus sp. PCC7942 for osmotic concentration and pH range from below pH 7.0 up to pH 10.0, the strain emerges as the ideal candidate for potential future medical application