Characterization on nicotine degradation and research on heavy metal resistance of a strain Pseudomonas sp. NBB

Abstract

The remediation of polluted sites containing multiple contaminants like nicotine and heavy metals poses significant challenges, due to detrimental effects like cell death. In this study, we isolated a new strain Pseudomonas sp. NBB capable of efficiently degrading nicotine even in high level of heavy metals. It degraded nicotine through pyrrolidine pathway and displayed minimum inhibitory concentrations of 2 mM for barium, copper, and lead, and 5 mM for manganese. In the presence of 2 mM Ba²⁺ or Pb²⁺, 3 g L^-1 nicotine could be completely degraded within 24 h. Moreover, under 0.5 mM Cu²⁺ or 5 mM Mn²⁺ stress, 24.13% and 72.56% of nicotine degradation were achieved in 60 h, respectively. Strain NBB tolerances metal stress by various strategies, including morphological changes, up-regulation of macromolecule transporters, cellular response to DNA damage, and down-regulation of ABC transporters. Notably, among the 153 up-regulated genes, cds_821 was identified as manganese exporter (MneA) after gene disruption and recovery experiments. This study presents a novel strain capable of efficiently degrading nicotine and displaying remarkable resistance to heavy metals. The findings of this research provide valuable insights into the potential application of nicotine bioremediation in heavy metal-contaminated areas.

Keywords: Heavy metal resistance; MneA; Multiple pollutants; Nicotine degradation; Pyrrolidine pathway.