Identifying the Metabolic Differences of a Fast-Growth Phenotype in Synechococcus UTEX 2973

Area of Science:

• Microbiology
• Metabolic Engineering
• Synthetic Biology

Background:

• Cyanobacteria possess photosynthetic capabilities valuable for industrial bioproduction.
• Limited growth rates hinder large-scale cyanobacterial applications compared to industrial standards.
• Synechococcus UTEX 2973 exhibits the fastest known cyanobacterial growth rate.

Purpose of the Study:

• To develop a genome-scale metabolic model (iSyu683) for Synechococcus UTEX 2973 to aid its development as a model organism.
• To investigate the factors contributing to the divergent growth rates between Synechococcus 2973 and Synechococcus PCC 7942.

Main Methods:

• Construction of the genome-scale metabolic model iSyu683.
• Integration of experimental data on CO2 uptake rates and biomass composition.
• Application of constraints based on measured CO2 uptake to simulate growth rates.

Main Results:

• The metabolic model accurately predicted a growth rate ratio of 2.03 between Synechococcus 2973 and 7942, closely matching the in vivo ratio of 2.13.
• Differences in carbon uptake rates were identified as the primary driver of divergent growth rates.
• Four single nucleotide polymorphisms (SNPs) were identified as potential contributors to altered enzyme kinetics.

Conclusions:

• The developed metabolic model facilitates research on fast-growing cyanobacteria.
• Carbon uptake efficiency is a critical determinant of growth rate in Synechococcus strains.
• Identified SNPs and cytochrome c oxidase operon correlations offer targets for future metabolic engineering efforts.