深海邻苯二甲酸酯降解真菌的降解机制研究

邻苯二甲酸酯（PAEs）作为塑料产品中的增塑剂已被发现具有内分泌干扰毒性。随着塑料工业的发展，这类物质对海洋生态环境造成巨大的威胁。海洋微生物已证明具有降解PAEs的潜力。但是目前的研究主要集中在近海包括红树林环境的微生物。深海微生物特别是深海真菌PAEs降解的研究还未见报道。在前期的研究中，我们从大洋深海底质中分离获得3株高效PAEs降解真菌,并发现其中Rhodotorula mucilaginosa MAR-Y3这株菌对于邻苯二甲酸二甲酯（DMPEs）的三种同分异构体的降解途径有很大的不同，且对于邻位的苯二甲酸二甲酯的降解存在着一条未知的新降解途径。本项研究拟对3株深海真菌的DMPEs降解途径进行分析，探求不同种属的深海真菌PAEs降解途径的共性与特性。同时对降解过程涉及的关键酶--酯酶、双加氧酶进行分子特征与催化活性研究，从化学代谢、酶蛋白两方面探索深海真菌的PAEs降解机制。

Plastic products give a lot of convenience in our daily lives. However, their wide utilization also causes serious environmental pollution problems. Phthalate esters (PAEs) are used as plasticizers in plastic products and these compounds have been identified as toxic pollutants due to their endocrine-disrupting functions. With the rapid development of plastic industry, PAEs may pose serious threat in marine ecological system. Marine microorganisms have been demonstrated the potential to degrade PAEs. However, most of current reports focus on coastal microorganisms, including mangrove microorganisms. Degradation study of these compounds by deep sea microorganisms is comparatively scarce, and no reports so far are available for degradation of PAEs by deep sea fungi. In our previous studies, three fungi capable of degrading PAEs have been isolated from deep sea sediments, including Rhodotorula mucilaginosa MAR-Y3, Rhodosporidium paludigenum MAR-Y4, and Aspergillus sp. IR-M4. It was found that Rhodotorula mucilaginosa MAR-Y3 proceeded through different biochemical pathways to degrade three isomers of dimethyl phthalate esters (DMPEs), and there is a new unpublished pathway for degradation of dimethyl phthalate by the fungus. Therefore, this study aims to investigate the biochemical degradation pathways of DMPEs by three deep sea fungi, to assess the general and specific characters of degradation pathways for different deep sea fungal species, and to characterize the molecular and catalytic characteristics of key enzymes (esterase and dioxgenase) involved in the degradation of PAEs. The results will contribute to understanding of the metabolic and enzymatic basis of degradation mechanisms of PAEs by deep sea fungi.