Reducing accumulation of cadmium in lettuce plants using nitrogen-fixing bacterial agent

Cadmium in soils is a global concern due to its toxicity and wide distribution. Bioremediation is an effective, environmentally friendly, and low-cost way to reduce Cd bioavailability in soils. In this study, we investigated the impact of a nitrogen-fixing bacterial agent (NFBA) on Cd accumulation in lettuce plants using both pot and field trials. The results showed that NFBA significantly affected the physicochemical properties of the soil, including pH, redox potential, organic matter content, and available nitrogen, which in turn affected cadmium bioavailability. The available Cd in soil was decreased significantly by 27.96% (p<0.01), resulting in a 21.76% decrease in Cd accumulation in lettuce plants (p<0.05). Furthermore, the growth and height of the lettuce plants were increased significantly by 36.63% and 25.60%, respectively (p<0.05), as demonstrated in the field trial. Additionally, the composition and activities of the rhizosphere soil microbial communities were significantly changed by NFBA. More abundant ecologically beneficial bacteria, such as Aeromonas, Acinetobacter and Massilia, were observed in the soil amended with NFBA. This study provides a feasible method for using nitrogenfixing bacteria to reduce cadmium accumulation in plants grown in Cd-contaminated soils.