Functional analysis of the agnH gene involved in nicotine-degradation pathways in Agrobacterium tumefaciens strain SCUEC1

Abstract

Agrobacterium tumefaciens strain SCUEC1 is a nicotine-degrading bacterium, which has been recently isolated from the tobacco waste-contaminated field soil. However, the mechanism for nicotine degradation in this strain remains unclear. Here, we analyze the function and biological properties of the agnH gene in the strain SCUEC1. The overexpression of the AgnH protein was detected by SDS-PAGE analysis, and functional insight of the AgnH protein was carried out with monitoring the changes of maleic acid into fumaric acid by high performance liquid chromatography (HPLC). Moreover, the effects of temperature, pH and metal ions on the enzymatic activities of the AgnH protein were also analyzed. The results demonstrated that the agnH gene was successfully ligated to the plasmid pET28a. The optimal condition for the enzymatic activities for the AgnH, approximately 28.0 kDa, was determined as 37 °C, pH 8.0 and 25 µM Mg2+. Conclusively, the agnH gene fulfils an important role in the conversion of maleic acid into fumaric acid involved in nicotine-degradation pathways in Agrobacterium tumefaciens strain SCUEC1.

Bacillus sp. YC7 from intestines of Lasioderma serricorne degrades nicotine due to nicotine dehydrogenase

“…Additionally, Wang L. et al studied an A. nicotinovorans molybdenum hydroxylase KDH, which plays a signicant role in nicotine degradation (Wang et al 2021 ). The agnH gene in A. tumefaciens strain SCUEC1 and the ocnE gene in O. intermedium SCUEC4 involved in nicotine-degradation pathways, have also been investigated (Xia et al 2020 ; Yu et al 2021 ). Notably, the nicotine-degrading enzyme, NicA2, has demonstrated its potential in reducing nicotine levels in the blood, nicotine distribution in the brain, and nicotine discrimination and reinforcement in rats (Pentel et al 2018 ).…”

“…Tobacco is an important cash crop that is primarily used to produce tobacco products and pesticide insecticides. Nicotine insecticides have been widely used in agricultural production since the 1980s (Matsuda et al 2020 ; Xia et al 2020 ), but they produce a large number of toxic wastes during production processing and consumption. Only 5% of these wastes can be absorbed by crops.…”

“…Only 5% of these wastes can be absorbed by crops. The remaining wastes spread and diffuse to the atmosphere, soil, water, plants, animals, and the human body, thus seriously polluting the environment (Matsuda et al 2020 ) and threatening human health (Xia et al 2020 ). Globally, 6.7 Mt of tobacco is produced annually, of which China accounts for the largest share at 39.6%, and the tobacco industry is expected to produce approximately 300,274 t of waste each year (He et al 2019 ; Najme et al 2021 ).…”

“…With the increasing recognition of the adverse effects of nicotine on human health and the environment, the exploration of microbial degradation pathways, especially in tobacco beetles’ intestinal flora, has become a new and exciting research focus (Huang et al 2020 ; Mu et al 2020 ; Xia et al 2020 ; Yu et al 2021 ; Zhang et al 2022 ). Harnessing the natural biodegradation capabilities of these microorganisms holds the promise of offering a greener and more efficient approach to tackle nicotine pollution.…”