Enhanced Multi-Stress Tolerance in <i>Escherichia coli</i> via the Heterologous Expression of <i>Zymomonas mobilis recA</i>: Implications for Industrial Strain Engineering

This study investigated the role of the <i>Zymomonas mobilis recA</i> gene in conferring stress resistance when expressed in <i>Escherichia coli</i>. The <i>recA</i> gene was cloned and expressed in <i>E. coli</i> BL21(DE3), producing a 39 kDa polypeptide. The results of comparative analyses demonstrated that the recombinant strain significantly enhanced survival rates under various stress conditions. In oxidative stress tests, the recombinant <i>E. coli</i> pET-22b(+)-recA exhibited superior survival at 3 mM and 5 mM H₂O₂ concentrations. Heat stress experiments at 50 °C and 55 °C revealed increased survival for the recombinant strain. Under ethanol stress, particularly at 20% (<i>v</i>/<i>v</i>), <i>E. coli</i> pET-22b(+)-recA displayed higher viability than controls. UV-C exposure tests further highlighted the protective effect of <i>recA</i> expression, with the recombinant strain maintaining viability after 60 min of exposure, while control strains showed no survival. These results indicate that the <i>Z. mobilis recA</i> gene product enhances resistance to oxidative, heat, ethanol, and UV-C stresses when expressed in <i>E. coli</i>. This study elucidates the broad stress-protective functions of the RecA protein across bacterial species and suggests potential applications in developing stress-tolerant bacterial strains for biotechnological purposes.