The degradation characteristics and pathways of organophosphorus flame retardants mixtures by Bacillus pacificus
LUO Ya-yan1, TANG Hui-qi1, LI Yi-yuan1, OUYANG Hao-min1,2, HUANG Hong1, CHEN Shuo-na1,3, QIU Rong-liang1,2,3
1. College of Natural Resource and Environment, South China Agricultural University, Guangzhou 510642, China; 2. Heyuan Branch, Guangdong Laboratory for Lingnan Modern Agriculture Project, Heyuan 517000, China; 3. Guangdong Provincial Key Laboratory of Agricultural & Rural Pollution Abatement and Environmental Safety, Guangzhou 510642, China
Abstract：In order to obtain more microbial species for degrading organophosphate flame retardants (OPFRs), and to reveal the pathway and mechanism of OPFRs biodegradation, the present isolated study a strain named Bacillus pacificus isolated from the residual sludge of a wastewater treatment plant in Guangzhou. The strain was proved to degrade a variety of OPFRs mixtures (including tris(2-chloroethyl) phosphate (TCEP), tris(2-chloropropyl) phosphate (TCPP), tritolyl Phosphate (TCP) and triphenyl phosphate (TPhP)). Bacillus pacificus used these four representative OPFRs as phosphorus sources for growth and metabolism. The results showed that 1.0mg/L TCP could be degraded efficiently by 1.0g/L of Bacillus pacificus, whose removal rate was 96.1% on the 9th day. While the biodegradation rates of other threes OPFRs were 23% to 34%. The four OPFRs were mainly degraded via phosphoester bond hydrolysis, and the final degradation produsts were small molecule compounds such as chloroethanol, chloropropanol, phosphoric acid, and benzene. In addition, TCEP and TCPP could be also decomposed by terminal dechlorination to produce tripropyl phosphate and tris(2-ethylpropyl) phosphate. TCP could be decomposed to trimethyl phosphate by methoxylation. The present study indicate that Bacillus pacificus can tolerate and effectively OPFRs mixtures, which can provide new ideas and high-quality microbial strain resources for OPFRs pollution management.
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