Interlink between ExoD (Alr2882), exopolysaccharide synthesis and metal tolerance in Nostoc sp. strain PCC 7120: Insight into its role, paralogs and evolution

Application of Cyanobacteria as Chassis Cells in Synthetic Biology

Synthetic biology is an exciting new area of research that combines science and engineering to design and build new biological functions and systems. Predictably, with the development of synthetic biology, more efficient and economical photosynthetic microalgae chassis will be successfully constructed, making it possible to break through laboratory research into large-scale industrial applications. The synthesis of a range of biochemicals has been demonstrated in cyanobacteria; however, low product titers are the biggest barrier to the commercialization of cyanobacterial biotechnology. This review summarizes the applied improvement strategies from the perspectives of cyanobacteria chassis cells and synthetic biology. The harvest advantages of cyanobacterial products and the latest progress in improving production strategies are discussed according to the product status. As cyanobacteria synthetic biology is still in its infancy, apart from the achievements made, the difficulties and challenges in the application and development of cyanobacteria genetic tool kits in biochemical synthesis, environmental monitoring, and remediation were assessed.

Genomic attributes and characterization of novel exopolysaccharide-producing bacterium Halomonas piscis sp. nov. isolated from jeotgal

Halophilic bacterial strains, designated SG2L-4T, SB1M4, and SB2L-5, were isolated from jeotgal, a traditional Korean fermented food. Cells are Gram-stain-negative, aerobic, non-motile, rod-shaped, catalase-positive, and oxidase-negative. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain SG2L-4T is closely related to Halomonas garicola KACC 18117T with a similarity of 96.2%. The complete genome sequence of strain SG2L-4T was 3,227,066 bp in size, with a genomic G + C content of 63.3 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain SG2L-4T and H. garicola KACC 18117T were 90.5 and 40.7%, respectively. The optimal growth conditions for strain SG2L-4T were temperatures between 30 and 37°C, a pH value of 7, and the presence of 10% (w/v) NaCl. The polar lipids identified included diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, an unknown phospholipid, an unknown glycolipid, and an unknown polar lipid. The major cellular fatty acids were C16:0, summed features 8 (C18:1ω6c and/or C18:1ω7c), C19:0 cyclo ω8c, and summed features 3 (C16:1ω6c and/or C16:1ω7c). The predominant respiratory quinone was ubiquinone with nine isoprene units (Q-9). Based on the phenotypic, genotypic, and chemotaxonomic results, strain SG2L-4T represents a novel species within the genus Halomonas, for which the name Halomonas piscis sp. nov. is proposed. The type strain is SG2L-4T (=KCTC 92842T = JCM 35929T). Functional annotation of the genome of strain SG2L-4T confirmed the presence of exopolysaccharide synthesis protein (ExoD) and capsular polysaccharide-related genes. Strain SG2L-4T also exhibited positive results in Molisch's test, indicating the presence of extracellular carbohydrates and exopolysaccharides (EPS) production. These findings provide valuable insights into the EPS-producing capabilities of H. piscis sp. nov. isolated from jeotgal, contributing to understanding its potential roles in food and biotechnological applications.