Serratia Marcescens and Enterobacter Cloacae: Agents of Heavy Metal Stress Relief for Wheat (Triticum aestivum) Seeds Germination

This research aimed to investigate the bioremediation potential of bacterial strains for chromium and copper, as well as their ability to alleviate heavy metal stress on wheat seed germination. Two bacterial strains, Serratia marcescens W2 and Enterobacter cloacae W7, were selected. The minimum inhibitory concentration (MIC) values for S. marcescens W2 were 300 ppm for Cr6+ and 1700 ppm for Cu2+ while for E. cloacae W7, the MIC values were 250 ppm for Cr6+ and 1350 ppm for Cu2+. Atomic absorption spectroscopy was used to determine the reduction and removal potential of these bacterial strains for Cu and Cr. Both strains demonstrated greater efficiency in reducing chromium compared to removing copper. S. marcescens W2 and E. cloacae W7 removed 26.4% and 28.7% of Cu2+ from the culture media after 24 hours, and 30.02% and 32.31% respectively after 48 hours. E. cloacae W7 and S. marcescens W2 reduced 56.95% and 65.65% of Cr6+ from the culture media after 24 hours, and 80.0% and 71.55% respectively after 48 hours. The effect of these bacterial strains on wheat seed germination showed increased root and shoot lengths compared to untreated seeds. When seeds were exposed to heavy metals like Cr6+ and Cu2+, root and shoot lengths significantly decreased. However, treatment with the bacterial strains and subsequent exposure to heavy metals resulted in increased root and shoot lengths post-germination. These bacteria can be effectively used for the removal of Cr6+ and Cu2+ from the environment and as plant growth-promoting bacteria for wheat and other crops