  Increased Atmospheric CO2 to over 400 ppm has prompted global climate
irregularities. Reducing the released CO2 from biotechnological processes could
remediate these phenomena. In this study, we sought to find a solution to
reduce the amount of CO2 in the process of growth and reproduction by
preventing the conversion of formic acid into CO2. The (bio)chemical conversion
of formic acid to CO2 is a key reaction. Therefore, we compared the growth of
BL21, being a subfamily of K12, alongside two strains in which two different
genes related to the formate metabolism were deleted, in complex and simple
media. Experimental results were entirely consistent with metabolic
predictions. Subsequently, the knockout bacteria grew more efficiently than
BL21. Interestingly, TsFDH, a formate dehydrogenase with the tendency of
converting CO2 to formate, increased the growth of all strains compared with
cells without the TsFDH. Most mutants grew in a simple medium containing
glycerol, which showed that glycerol is the preferred carbon source compared to
glucose for the growth of E. coli. These results explain the reasons for the
inconsistency of predictions in previous metabolic models that declared
glycerol as a suitable carbon source for the growth of E. coli but failed to
achieve it in practice. To conduct a more mechanistic evaluation of our
observations, RNA sequencing data analysis was conducted on an E. coli RNA-seq
dataset. The gene expression correlation outcome revealed the increased
expression levels of several genes related to protein biosynthesis and glycerol
degradation as a possible explanation of our observations.
