日前，北京航空航天大学杨军研究组和美国斯坦福大学吴唯民高级研究员、深圳华大基因公司赵姣博士等，在继2014年12月发表蜡虫肠道微生物降解聚乙烯的论文后，再次在国际环境科学与技术领域权威期刊《Environmental Science and Technology》上发表了题为“Biodegradation and mineralization of polystyrene by plastic-eating mealworms. Part 1. Chemical and physical characterization andisotopic tests”（啮食塑料黄粉虫对聚苯乙烯的生物降解和完全矿化作用：1. 化学与物理特性和同位素失踪试验）和“Biodegradation and mineralization of polystyrene by plastic-eating mealworms.Part 2. Role of gut microorganisms”（啮食塑料黄粉虫对聚苯乙烯的生物降解和完全矿化作用：2. 肠道微生物的作用）两篇姊妹研究论文，首次以全面证据揭示了黄粉虫啮食降解聚苯乙烯、将其完全降解矿化为二氧化碳、并利用同化为虫体脂肪，同时证明是其肠道微生物起主导作用，并且分离鉴定了一株降解聚苯乙烯的细菌。此研究成果为解决废弃塑料污染环境的问题提供了崭新的思维。

石油化工生产的塑料废物污染是世界环境难题。迄今为止学术界认为，塑料产品由于物理化学结构稳定、在自然环境中可能数十至数百年不会被分解。塑料污染正严重威胁着生态和海洋环境。2013年石油基塑料世界年产量约3亿吨，其中聚苯乙烯占7.1%。聚苯乙烯经久耐用，不能生物降解，常用作一次性饭盒、咖啡杯和包装绝热材料，在土壤、河流湖泊及海洋等环境产生了普遍严重的“白色污染”。2005年起，北京航空航天大学化学与环境学院杨军博士开始了塑料生物降解的研究。

黄粉虫又名面包虫，拉丁学名Tenebriomolitor。一般长20-25mm，成虫为黑色甲虫，是一种仓库害虫，原产北美洲，现已被人工大量饲养用作动物饲料或者提取化工原料。在北航和斯坦福的实验表明，产自中国和美国的黄粉虫幼虫都啮食塑料，仅仅靠啮食泡沫塑料能存活一个月以上，最后发育成甲壳成虫。聚苯乙烯泡沫塑料在黄粉虫幼虫肠道停留时间短于24小时。进食泡沫塑料16天后，黄粉虫可以将大约48%的聚苯乙烯转化为二氧化碳。碳-13同位素示踪实验证明，聚苯乙烯被黄粉虫完全降解矿化为二氧化碳和利用转化为虫体脂肪。

研究组发现肠道微生物对聚苯乙烯生物降解起决定性的作用。在黄粉虫幼虫食物中加入抗生素抑制肠道微生物后，幼虫不能降解塑料。他们进一步成功分离出可以利用聚苯乙烯作为唯一碳源进行生长的聚苯乙烯降解细菌--微小杆菌YT2（Exiguobacteriumsp. YT2）。该菌株已保存在中国微生物菌种保藏管理委员会普通微生物中心和国家基因库，是国际上报道的第一株保藏在菌种中心的聚苯乙烯降解细菌。该株细菌可在在无碳琼脂固体培养基上的聚苯乙烯膜表面生长生成稳定的生物膜，显著地侵蚀膜表面结构。该菌株在液体中培养60天后，液体中聚苯乙烯碎屑被分解、减重可达7.4%。残留物的分子量明显降低，生成大量水溶性的低分子中间产物。

该系列研究再次提供了有力的科学证据，证实微生物能直接有效地降解聚苯乙烯，同时也进一步证实具有取食塑料行为的昆虫的肠道是发现降解塑料的微生物的重要来源。这为开发生物降解高分子材料和废弃物的技术提供了一条全新的途径。

文章第一作者杨宇是通讯作者江雷院士和杨军副教授合作指导的博士生，吴唯民博士参加并指导了研究工作，赵姣博士和杨瑞馥教授参加了微生物基因组分析工作，宋怡玲和高龙成副教授参加了前期微生物实验和高分子分析工作。

该研究得到了国家自然科学基金、国家重点基础研究发展计划（973）以及深圳市生物能源重点实验室的资助。

两篇文章在发表的当日，美国Chemical &Engineering News（C&EN，化学与工程新闻）进行了采访报道。Stanford News（斯坦福新闻）提前采访报道了研究成果，并指出杨军博士正在领导与斯坦福大学Craig Criddle教授进行国际合作的研究计划。

世界主要通讯媒体如美国CNN、 CNBC、VOA、The Huffington Post（赫芬顿邮报，美国最具影响力的新闻博客网站）、The Times（英国泰晤士报）先后采访了文章作者，进行了报道。FOX News、UPI （United Press International，美国第二大通讯社合众国际社）等数百家媒体作了转载。（来源：科学网 李琳）

Biodegradation and Mineralization of Polystyrene by Plastic-Eating Mealworms: Part 1. Chemical and Physical Characterization and Isotopic Tests

Abstract  Polystyrene (PS) is generally considered to be durable and resistant to biodegradation. Mealworms (the larvae of Tenebrio molitor Linnaeus) from different sources chew and eat Styrofoam, a common PS product. The Styrofoam was efficiently degraded in the larval gut within a retention time of less than 24 h. Fed with Styrofoam as the sole diet, the larvae lived as well as those fed with a normal diet (bran) over a period of 1 month. The analysis of fecula egested from Styrofoam-feeding larvae, using gel permeation chromatography (GPC), solid-state 13C cross-polarization/magic angle spinning nuclear magnetic resonance (CP/MAS NMR) spectroscopy, and thermogravimetric Fourier transform infrared (TG–FTIR) spectroscopy, substantiated that cleavage/depolymerization of long-chain PS molecules and the formation of depolymerized metabolites occurred in the larval gut. Within a 16 day test period, 47.7% of the ingested Styrofoam carbon was converted into CO2 and the residue (ca. 49.2%) was egested as fecula with a limited fraction incorporated into biomass (ca. 0.5%). Tests with α 13C- or β 13C-labeled PS confirmed that the 13C-labeled PS was mineralized to 13CO2 and incorporated into lipids. The discovery of the rapid biodegradation of PS in the larval gut reveals a new fate for plastic waste in the environment.

原文链接：http://pubs.acs.org/doi/pdf/10.1021/acs.est.5b02661

Biodegradation and Mineralization of Polystyrene by Plastic-Eating Mealworms: Part 2. Role of Gut Microorganisms

Abstract  The role of gut bacteria of mealworms (the larvae of Tenebrio molitor Linnaeus) in polystyrene (PS) degradation was investigated. Gentamicin was the most effective inhibitor of gut bacteria among six antibiotics tested. Gut bacterial activities were essentially suppressed by feeding gentamicin food (30 mg/g) for 10 days. Gentamicin-feeding mealworms lost the ability to depolymerize PS and mineralize PS into CO2, as determined by characterizing worm fecula and feeding with 13C-labeled PS. A PS-degrading bacterial strain was isolated from the guts of the mealworms, Exiguobacterium sp. strain YT2, which could form biofilm on PS film over a 28 day incubation period and made obvious pits and cavities (0.2–0.3 mm in width) on PS film surfaces associated with decreases in hydrophobicity and the formation of C–O polar groups. A suspension culture of strain YT2 (108 cells/mL) was able to degrade 7.4 ± 0.4% of the PS pieces (2500 mg/L) over a 60 day incubation period. The molecular weight of the residual PS pieces was lower, and the release of water-soluble daughter products was detected. The results indicated the essential role of gut bacteria in PS biodegradation and mineralization, confirmed the presence of PS-degrading gut bacteria, and demonstrated the biodegradation of PS by mealworms.

原文链接：http://pubs.acs.org/doi/pdf/10.1021/acs.est.5b02663