Water Research Institute (IRSA) (CNR), Via Salaria km 29, 300, 00015 Monterotondo, Rome, Italy.
Water Research Institute (IRSA) (CNR), Via Salaria km 29, 300, 00015 Monterotondo, Rome, Italy.
Sci Total Environ. 2020 Dec 20;749:141608. doi: 10.1016/j.scitotenv.2020.141608. Epub 2020 Aug 10.
Pollution of aquatic ecosystems by plastic wastes poses severe environmental and health problems and has prompted scientific investigations on the fate and factors contributing to the modification of plastics in the marine environment. Here, we investigated, by means of microcosm studies, the role of hydrocarbon-degrading bacteria in the degradation of poly(ethylene terephthalate) (PET), the main constituents of plastic bottles, in the marine environment. To this aim, different bacterial consortia, previously acclimated to representative hydrocarbons fractions namely, tetradecane (aliphatic fraction), diesel (mixture of hydrocarbons), and naphthalene/phenantrene (aromatic fraction), were used as inocula of microcosm experiments, in order to identify peculiar specialization in poly(ethylene terephthalate) degradation. Upon formation of a mature biofilm on the surface of poly(ethylene terephthalate) films, the bacterial biodiversity and degradation efficiency of each selected consortium was analyzed. Notably, significant differences on biofilm biodiversity were observed with distinctive hydrocarbons-degraders being enriched on poly(ethylene terephthalate) surface, such as Alcanivorax, Hyphomonas, and Cycloclasticus species. Interestingly, ATR-FTIR analyses, supported by SEM and water contact angle measurements, revealed major alterations of the surface chemistry and morphology of PET films, mainly driven by the bacterial consortia enriched on tetradecane and diesel. Distinctive signatures of microbial activity were the alteration of the FTIR spectra as a consequence of PET chain scission through the hydrolysis of the ester bond, the increased sample hydrophobicity as well as the formation of small cracks and cavities on the surface of the film. In conclusion, our study demonstrates for the first time that hydrocarbons-degrading marine bacteria have the potential to degrade poly(ethylene terephthalate), although their degradative activity could potentially trigger the formation of harmful microplastics in the marine environment.
塑料废物对水生生态系统的污染造成了严重的环境和健康问题，促使科学家们对塑料在海洋环境中的命运和促成其变化的因素进行了科学研究。在这里，我们通过微宇宙研究调查了烃降解细菌在海洋环境中降解聚酯（PET）的作用，PET 是塑料瓶的主要成分。为此，我们使用了先前适应代表性烃类物质的不同细菌群落，例如十四烷（脂族部分）、柴油（烃混合物）和萘/菲（芳族部分），作为微宇宙实验的接种物，以确定其在聚酯降解方面的特殊专业化。在聚酯薄膜表面形成成熟的生物膜后，分析了每个选定的群落的细菌生物多样性和降解效率。值得注意的是，在生物膜生物多样性方面观察到了显著的差异，具有独特烃降解特性的细菌在聚酯表面得到了富集，例如 Alcanivorax、Hyphomonas 和 Cycloclasticus 属。有趣的是，ATR-FTIR 分析得到 SEM 和水接触角测量的支持，揭示了 PET 薄膜表面化学性质和形态的主要变化，这主要是由富集在十四烷和柴油上的细菌群落驱动的。微生物活性的独特特征是 FTIR 光谱的改变，这是由于聚酯链通过酯键的水解而断裂，导致样品疏水性增加，以及薄膜表面形成小裂缝和凹坑。总之，我们的研究首次证明了海洋烃降解细菌具有降解聚酯的潜力，尽管它们的降解活性可能会在海洋环境中引发有害微塑料的形成。
