Abstract：
Phthalic acid esters (PAEs) plasticizers are virulent endocrine disruptors that are mixed into plastics while fabricating and can filter out once they release into the surrounding environments. Plastic surfaces serve as new habitats for microorganisms, referred to as \'plastisphere\'. Previous metagenomic investigations of the \'plastisphere\' indicated that marine plastic surfaces may harbor microbes that degrade PAEs plasticizers. To our knowledge, the potential of microorganisms in the marine \'plastisphere\' to metabolize PAEs is poorly understood. In this study, by screening the natural microbial community on plastic debris that had been deployed in situ for up to 20 months, a novel marine bacterium, Microbacterium esteraromaticum DEHP-1, was successfully isolated, which could degrade and mineralize 10-200 mg/L dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP). According to the results of gas chromatography-mass spectrometry (GC-MS) and whole genome mining of strain DEHP-1, we found that strain DEHP-1 may metabolize DBP by successive removal of the ester side chain by esterase 2518 to produce mono-butyl phthalate (MBP) and phthalic acid (PA), whereas the degradation of DEHP may take place by the direct action of monooxygenase 0132 on the fatty acid side chain of the DEHP molecule to produce di-n-hexyl phthalate (DnHP) and DBP, and then the subsequent hydrolysis of DBP by de-esterification to PA and finally into the tricarboxylic acid (TCA) cycle. Non-targeted metabolomics results showed that intracellular degradation of PAEs did not happen. However, exposure to PAEs was found to significantly affect pathways such as arginine and proline, riboflavin, glutathione and lysine degradation. Therefore, the intracellular metabolic behavior of strain DEHP-1 exposed to PAEs was proposed for the first time. This study sheds light on the metabolic capacity and strategies of bacteria in the marine \'plastisphere\' to effectively degrade PAEs and highlights the importance of marine microbes in mitigating plastic poisonousness.
摘要：
邻苯二甲酸酯（PAEs）增塑剂是有毒的内分泌干扰物，在制造时混入塑料中，一旦释放到周围环境中就可以过滤掉。塑料表面成为微生物的新栖息地，称为“plastitphere”。先前对“质体”的宏基因组研究表明，海洋塑料表面可能含有降解PAEs增塑剂的微生物。据我们所知,对海洋“质体”中微生物代谢PAEs的潜力知之甚少。在这项研究中,通过在原位部署长达20个月的塑料碎片上筛选天然微生物群落，一种新的海洋细菌，成功地分离出芳香酯微杆菌DEHP-1，可以降解和矿化10-200mg/L的邻苯二甲酸二丁酯（DBP）和邻苯二甲酸二（2-乙基己基）酯（DEHP）。根据菌株DEHP-1的气相色谱-质谱（GC-MS）和全基因组挖掘结果，我们发现菌株DEHP-1可能通过酯酶2518连续去除酯侧链来代谢DBP，从而产生邻苯二甲酸单丁酯（MBP）和邻苯二甲酸（PA）。而DEHP的降解可以通过单加氧酶0132对DEHP分子的脂肪酸侧链的直接作用来产生邻苯二甲酸二正己酯（DnHP）和DBP，然后通过脱酯化将DBP水解为PA，最后进入三羧酸（TCA）循环。非靶向代谢组学结果显示,PAEs未发生细胞内降解。然而,发现接触PAEs会显著影响精氨酸和脯氨酸等途径，核黄素,谷胱甘肽和赖氨酸降解。因此,首次提出了菌株DEHP-1暴露于PAEs的细胞内代谢行为。这项研究揭示了海洋中细菌有效降解PAEs的代谢能力和策略，并强调了海洋微生物在减轻塑料毒性中的重要性。
