Deng Weiqin, Zhao Yun, Hu Kaidi, Chen Shujuan, He Li, Ao Xiaolin, Zou Likou, Hu Xinjie, Yang Yong, Liu Shuliang
College of Food Science, Sichuan Agricultural University, Ya'an, China.
Sichuan Institute of Research and Design About Food and Fermentation Industries, Chengdu, China.
Front Microbiol. 2019 Nov 8;10:2538. doi: 10.3389/fmicb.2019.02538. eCollection 2019.
Diethylstilbestrol (DES) can adversely affect the immune system of developing fetuses or even elicit toxic responses such as nerve toxicity and genotoxicity in human beings, thereby warranting methods to remove DES from the environments. The present study characterized a novel DES-degrading JF and analyzed the degradation metabolites. The strain was collected at the China General Microbiological Culture Collection Center (Collection number: CGMCC 7950). The environmental effects, such as DES concentrations, pH levels, and temperature, on the strain's degradation ability were tested. Degradation metabolites of DES by strain JF were analyzed via high performance liquid chromatography (HPLC) and liquid-chromatography time of flight mass spectrometry (LC-TOF-MS). Results indicated that JF can effectively degrade DES within a concentration of 25-200 mg/L. Increasing pH levels (pH > 7) are reported to increase the degradation rate of DES by the strain. The optimal temperature for strain JF to degrade DES was identified as 45°C. In this study, 4, 4'-hexene estrogen quinones (DESQ) and DES-4-semiquinone were speculated as two degradation metabolites of DES, and both can be completely degraded by strain JF. A slight reduction of DES in the blank system [DES cultured in Luria-Bertani (LB) medium without strain JF] was observed in this study. The reduction trend in the blank system only occurred during the first few days (about 4 days) and was considerably lesser than the decomposition and transformation effect of DES via strain JF. Furthermore, the metabolite DESQ could not be further decomposed in blank LB medium without strain JF. All the results demonstrate that complete degradation of DES in the fermentation broth occurs due to the function of strain JF rather than organic decomposition. In conclusion, the high efficiency of degradation and the potential to degrade DES completely indicates that strain JF has potential for the bioremediation of DES-contaminated environments (soil, river, and so on) and fermented foods.
己烯雌酚（DES）会对发育中的胎儿免疫系统产生不利影响，甚至会在人体中引发神经毒性和基因毒性等毒性反应，因此需要采取从环境中去除DES的方法。本研究对一种新型的DES降解菌株JF进行了表征，并分析了其降解代谢产物。该菌株保藏于中国普通微生物菌种保藏管理中心（保藏编号：CGMCC 7950）。测试了DES浓度、pH值和温度等环境因素对该菌株降解能力的影响。通过高效液相色谱（HPLC）和液相色谱飞行时间质谱（LC-TOF-MS）分析了菌株JF对DES的降解代谢产物。结果表明，JF能够在25-200 mg/L的浓度范围内有效降解DES。据报道，提高pH值（pH>7）会提高该菌株对DES的降解速率。确定菌株JF降解DES的最适温度为45℃。本研究推测4,4'-己烯雌酚醌（DESQ）和DES-4-半醌为DES的两种降解代谢产物，且二者均可被菌株JF完全降解。本研究观察到在空白系统[在不含菌株JF的Luria-Bertani（LB）培养基中培养的DES]中DES略有减少。空白系统中的减少趋势仅在最初几天（约4天）出现，且远小于DES通过菌株JF的分解转化效果。此外，在不含菌株JF的空白LB培养基中，代谢产物DESQ无法进一步分解。所有结果表明，发酵液中DES的完全降解是由于菌株JF的作用，而非有机分解。总之，高效的降解能力以及完全降解DES的潜力表明，菌株JF在对DES污染的环境（土壤、河流等）和发酵食品进行生物修复方面具有潜力。
