Isolation, identification, and degradation characteristics of a 1-nitroso-2-naphthol-degrading strain derived from nonferrous metal (loid) tailings

Abstract:

As a new representative flotation reagent, 1-nitroso-2-naphthol is widely used in the mining and metallurgical industry to improve the utilization rate of low-grade mineral resources. It is highly stable, posing a challenge to the treatment of heavy metal pollution and organic smelting agent pollution in mine. Among the crucial techniques for the remediation of polycyclic aromatic hydrocarbons (PAHs), bio-remediation is safe and efficient with low cost and no secondary pollution. [Objective] To screen an efficient 1-nitroso-2-naphthol-degrading strain from the typical non-ferrous metal tailings in the periphery of Hechi city, Guangxi Zhuang autonomous region in China, analyze the degradation characteristics and potential metabolic pathways, and thereby examine the conditions for the microbial remediation of the mine polluted by compound pollutants including PAHs. [Methods] The strain which used 1-nitroso-2-naphthol as the only carbon source was screened and identified by 16S rRNA gene sequencing. Gas chromatography-mass spectrometry (GC-MS) was employed to analyze degradation characteristics of 1-nitroso-2-naphthol and the intermediate metabolites, and the metabolic pathways were predicted. [Results] An efficient strain was screened out and identified as the Gram-negative Pseudomonas putida CUGB-JL11. Under the optimal conditions of 30 ℃ and pH 6-8, the 5-day degradation rate of 40 mg/L 1-nitroso-2-naphthol by the strain was up to 81%. The main intermediate metabolites were the benzodiazepines methyl N-hydroxybenzenecarboximidoate and amphetamine, but the organic substances and most of the intermediates were degraded into small molecules or completely degraded. [Conclusion] CUGB-JL11 boasts high 1-nitroso-2-naphthol-degrading efficiency and strong environmental adaptability. It has a huge potential for the treatment of PAHs. This study lays a theoretical basis and provides microbial resources for bioremediation of nonferrous metal mine polluted by both heavy metals and flotation reagents.