海洋粗油鞘氨醇菌RL-ZY01对磷酸三苯酯的生物降解及其应用

Biodegradation of triphenyl phosphate by Sphingobium naphthae RL-ZY01 and its application

摘要:

背景 磷酸三苯酯作为有机磷阻燃剂的典型代表，其大量使用给环境和人类健康带来了巨大威胁。目前已报道的磷酸三苯酯降解菌主要来自陆地生态系统，而海洋生态系统中的磷酸三苯酯降解菌鲜有报道。目的 分离可高效降解磷酸三苯酯的海洋细菌，系统阐明其对磷酸三苯酯的降解机理，并探索其应用潜能。方法 通过唯一碳源法分离可高效降解磷酸三苯酯的海洋微生物，通过单因素试验分析其对环境的适应性，基于代谢产物的质谱鉴定推测菌株降解磷酸三苯酯的代谢途径，通过生物强化探索菌株在生物修复及缓解磷酸三苯酯对植物毒性中的应用潜能。结果 从红树林沉积物中分离获得一株磷酸三苯酯降解菌RL-ZY01，该菌30 h内对100 mg/L磷酸三苯酯的降解率接近100%。通过形态学特征描述、16S rRNA基因分析、生理生化特征分析及基于全基因组的分类方法将菌株RL-ZY01鉴定为粗油鞘氨醇菌(Sphingobium naphthae)。该菌在pH 4.0-9.0、20-40 ℃、1.0%-9.0% NaCl和低浓度重金属(0.5 mmol/L)条件下，对100 mg/L磷酸三苯酯在32 h的降解率均在70%以上。通过代谢产物的质谱分析与鉴定，推测菌株通过逐步酯键水解将磷酸三苯酯转化为苯酚，苯酚再进一步被开环利用。菌株RL-ZY01对磷酸三苯酯污染的海洋样品表现出良好的生物修复潜能，在48 h内可将海水中50 mg/L磷酸三苯酯降解85.01%，在48 h内彻底降解红树林沉积物中40 mg/kg磷酸三苯酯；菌株RL-ZY01可有效缓解磷酸三苯酯对拟南芥的毒害作用，提高拟南芥种子的发芽率并促进拟南芥植株的生长。结论 磷酸三苯酯降解菌RL-ZY01为粗油鞘氨醇菌，该菌对环境温度、pH、盐离子浓度及重金属离子等具有较好的耐受能力，通过酯键的逐步水解将磷酸三苯酯转化为苯酚并进一步开环利用，菌株在生物修复及缓解磷酸三苯酯对植物毒性等方面表现出良好的应用潜力。

Abstract:

Background Triphenyl phosphate (TPHP), as a typical representative of organophosphorus flame retardants, has brought huge threats to the environment and human health due to its extensive application. Currently, most of known triphenyl phosphate-degrading microbes were isolated from terrestrial ecosystems, while those from marine ecosystems are rarely reported.Objective To isolate marine bacteria that efficiently degrade TPHP, further systematically elucidate their TPHP degradation mechanism and explore their application potential.Methods Using the sole carbon source method, we isolated marine bacteria with efficient TPHP degradation capability. Their environmental adaptability was assessed through single-factor experiments. Based on metabolite identification by mass spectrometry, we proposed a potential TPHP degradation pathway. Furthermore, biofortification experiments demonstrated the strain’s potential for bioremediation and TPHP phytotoxicity mitigation.Results A TPHP-degrading bacterial strain RL-ZY01, isolated from mangrove sediments, demonstrated near-complete degradation of 100 mg/L TPHP within 30 hours. Through comprehensive characterization, including morphological observation, 16S rRNA gene sequencing, physiological-biochemical tests, and whole-genome analysis, the strain was identified as Sphingobium naphthae. The strain RL-ZY01 maintained effective TPHP degradation (>70% of 100 mg/L TPHP after 32 h) across varying environmental conditions: pH 4.0-9.0, 20-40 ℃, 1.0%-9.0% NaCl, and in the presence of low heavy metal concentrations (0.5 mmol/L). Through mass spectrometry analysis and metabolite identification, it was speculated that the strain converted TPHP into phenol by stepwise hydrolysis of ester bonds, with phenol further utilized via ring opening. The strain RL-ZY01 showed good bioremediation potential for TPHP-contaminated marine samples. It could degrade 85.01% of 50 mg/L TPHP in seawater within 48 h and completely degrade 40 mg/kg TPHP in mangrove sediments within 48 h. Additionally, the strain RL-ZY01 effectively alleviated the toxic effect of TPHP on Arabidopsis thaliana, increasing the seed germination rate and promoting the seedling growth.Conclusion The TPHP-degrading strain RL-ZY01 was identified as S. naphthae. This strain exhibited strong tolerance to varying environmental conditions, including temperature, pH, salinity, and heavy metal ions. It degraded TPHP through stepwise ester bond hydrolysis to produce phenol, followed by ring-opening metabolism. The strain demonstrates promising potential for bioremediation and TPHP phytotoxicity mitigation.