Microbial Degradation Mechanism and Pathway of the Novel Insecticide Paichongding by a Newly Isolated Sphingobacterium sp. P1-3 from Soil

Abstract

Using 1-((6-chloropydidin-3-yl)methyl)-7-methyl-8-nitro-5propoxy-1,2,3,5,6,7-hexahydroimidazo[1,2-α-]-pyridine (IPP) as the sole carbon source, we isolated a strain with a higher activity of IPP-degrading bacterium Sphingobacterium sp. P1-3 from soil. At 30 °C, pH 7.0 ,and 10 mg L(-1) IPP content, the degradation rate of IPP by Sphingobacterium sp. P1-3 could reach 57.75 and 62.47% in 20 and 30 days, respectively. The value of DT50 of IPP was 27 d at the level of 30 mg L(-1) IPP, while DT50 in the blank test was 151 d. During the IPP biodegradation process, five intermediates (M1-M5) were monitored and identified. On the basis of the identified metabolites and their biodegradation courses, a possible biodegradation pathway was proposed. IPP biodegradation mainly occurred on the tetrahydropyridine ring. IPP was transformed to five different metabolites by strain P1-3 through the oxidation and elimination of methyl, propyl, and nitro groups. Moreover, a new pathway involving M2 (1-((6-chloropydidin-3-yl)methyl)-7-methyl-8-hydroxy-5-propoxy-1,2,3,5,6,7-hexahydroimidazo [1,2-α-]-pyridine), M3 (1-((6-chloropydidin-3-yl)methyl)-7-methyl-5-carbonyl-1,2,3,5,6,7-hexahydroimidazo[1,2-α-]-pyridine), and M5 (8-amino-1,2,3,5,6,7-hexahydroimidazo[1,2-α-]-pyridine) was first monitored and identified.

Impact of the novel neonicotinoid insecticide Paichongding on bacterial communities in yellow loam and Huangshi soils

“…IPP-degrading strain, Sphingobacterium sp. P1-3, was isolated and stored in the Laboratory of Applied Microbiology and Biotechnology, Changzhou University (Changzhou, China) (Cai et al 2015b). …”

“…These suggest that these genera were key bacterial group for IPP degradation in soil environment. Our previous study reported IPP-degrading strain, Sphingobacterium P1-3 (Cai et al 2015b), which was isolated from soil. Hence, this is the first record of IPPdegrading strains from other genera, suggesting that the broader taxonomic groups could contribute to IPP degradation in natural soil environments.…”

“…Paichongding (IPP, 1-((6-chloropydidin-3-yl) methyl)-7-methyl-8-nitro-5propoxy-1,2,3,5,6,7-hexahydroimidazo[1, 2-α-]-pyridine) is a novel nitromethylene neonicotinoid recently developed by the East China University of Science and Technology in China (Zhao et al 2010;Fu et al 2013a, b;Li et al 2013;Wang et al 2013;Zhang et al 2013;Cai et al 2015b). IPP is different from the traditional neonicotinoids as it is the antagonist of the postsynaptic nicotinic acetylcholine receptors (nAChRs) of insects.…”

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 1: new molecules, metabolism, fate, and transport

“…Microbial degradation in soil by a Sphingobacterium sp. mainly occurs on the tetrahydropyridine ring and produces five metabolites (Table 1) (Cai et al 2015b). In anaerobic soils, biodegradation of paichongding occurs via nitro reduction and elimination, hydrolysis, demethylation, and ether cleavage reactions, producing six metabolites (Table 1) (Cai et al 2015a).…”

Whole Genome Sequence of Sphingobacterium sp. G1-14, a Strain With Effective Paichongding Biodegradation

“…In the past two or three decades, neonicotinoid insecticides have become one of the largest sales insecticides in more than 120 countries around the world. As a representative of insecticide, Paichongding (IPP, 1-((6-chloropydidin-3-yl)methyl)-7-methyl-8-nitro-5propoxy-1,2,3,5,6,7-hexahydroimidazo[ 1,2-a-]-pyridine), was developed by Jiangsu Kwin Co., Ltd. and East China University of Science and Technology in 2008 and showed excellent activity for anti-imidacloprid insects (Cai et al, 2015;Qin et al, 2012;H. Y. Wang et al, 2013).…”