Characterization of New Cell Factory Candidate for Saudi Arabia Application

Abstract

Characterization of a New Cyanobacterial Cell Factory Strain for Saudi Arabia Application The use of photosynthetic cells as platform for bio-manufacturing is gaining increasing interest as it promises todeliver a sustainable, carbon neutral production system for biomass-derived chemicals, fuels and foods. SaudiArabia, in particular, is an excellent place for the deployment of photosynthetic cell factory as algal biotechnologyleverages the country’s abundant sunlight, availability of large CO2 point source emissions and access to Red Seaand Gulf waters (38 – 40 PSU). Currently a few model picocyanobacterial strain have been extensively studied forbiofuel and biochemical production, but these strains are limited to mild temperature, light and salinity conditionsthus cannot operate under Saudi Arabian climate. Therefore, in order to develop cyanobacterial cell factoryapplications for the Arabian Peninsula, there is a pressing need to discover and develop strains that can thriveunder extremely warm temperatures, high insolation and high salinity. In our study, a native unicellularSynechococcus sp. RSCCF101 strain isolated from the central Red Sea has been identified as a potential cellfactory candidate. Here we present physiological and genomic characterization of Synechococcus sp. RSCCF101to support its development as a new robust marine cell factory strain.

Summary •Strain RSCCF101 is a candidate marine cyanobacterial cell factory strain isolated from the central Red Sea. It has an ovoid structure of about 1 µm length and 0.8 µm diameter (Figure 1) and 16S rRNA phylogenetic tree analysis places RSCCF101 within the Synechoccocus cluster (Figure 2). •The physiological profile showed that Synechococcus sp. RSCCF101 is both thermo- and halotolerant where it is able to grow efficiently at temperature up to 38°C and salinity between 10 PSU and 40 PSU, while remained viable at 50 PSU and 60 PSU (Figure 3A and 3B). These are desirable characteristics of a cell factory candidate as the chassis strain has to be able to survive the warm climate and intense insolation in Saudi Arabia (Nielsen, Archer et al. 2017). •Synechococcus sp. RSCCF101 is capable of producing high amount of phycocyanin under low light condition and glycogen under high light condition (Figure 4A to 4D). Phycocyanin is a valuable product for bioassay, bioimaging, pharmaceutical, food and cosmetics industry application (Chakdar and Pabbi 2016) while glycogen can be used as biofuel feedstock (Aikawa, Nishida et al. 2014). •Whole genome was successfully constructed for Synechococcus sp. RSCCF101 (Figure 5), from which a complete gene set involving in glycogen biosynthesis was identified (Figure 6). In addition, the genome contains three sets of cpcBA which encodes the alpha and beta subunits of phycocyanin (Figure 7). •Future work will include a more detailed genomic and transcriptomic profiling of RSCCF101 to establish the understanding of the physiological and molecular traits for synthetic biology purposes.