Strengthening bioremediation potential: Enterobacter ludwigii ES2 for combined nicosulfuron and Cd contamination through whole genome and microbial diversity community analysis

Abstract

Nicosulfuron and Cd are common pollutants that pose significant threats to the environment and human health, particularly under combined stress. This study is the first to remediate environmental nicosulfuron and Cd under combined stress using microbiological techniques. Enterobacter ludwigii ES2 was isolated, characterized, and demonstrated to degrade 93.80 % of nicosulfuron and remove 59.64 % of Cd within 4 d. Potential functional genes, including nicosulfuron degradation genes gstA, gstB, glnQ, glnP, mreB, and sixA, and Cd tolerance/removal-related genes mntA, mntB, mntH, dnaK, znuA, and zupt, were predicted by sequencing the whole genome of strain ES2, and their expression was verified by qRT-PCR. Strain ES2 managed oxidative stress induced by Cd through superoxide dismutase, glutathione, catalase, peroxidase, and malondialdehyde. Furthermore, to repair compound stress, up to 90.48 % of nicosulfuron and 67.74 % of Cd were removed. The community structure analysis indicated that Enterobacteriaceae, Sphingomonadaceae, and Gemmatimonadaceae were dominant populations, with ES2 stably colonizing and becoming the dominant bacterium. In summary, ES2 demonstrated significant potential in remediating nicosulfuron and Cd pollution from various perspectives, providing a solid theoretical foundation.