塑料废物被认为是最常见和持久的海洋污染物。不仅在浅水中发现,但也在海底。然而,深海微生物是否已经进化出降解塑料的能力仍然难以捉摸。在这项研究中,发现一种深海细菌VelezensisGUIA能够降解水性聚氨酯。转录组分析表明,补充水性聚氨酯上调了许多与孢子萌发相关的基因的表达,表明塑料的存在对菌株GUIA的生长有影响。此外,水性聚氨酯的补充也明显上调了许多编码脂肪酶的基因的表达,蛋白酶,和氧化还原酶。液相色谱-质谱(LC-MS)结果表明,在菌株GUIA中负责塑料降解的潜在酶被鉴定为氧化还原酶,蛋白酶,还有脂肪酶,这与转录组学分析一致。结合体外表达和降解测定以及傅里叶变换红外(FTIR)分析,我们证明了菌株GUIA的氧化还原酶Oxr-1是水性聚氨酯的关键降解酶。此外,氧化还原酶Oxr-1也被证明可以降解可生物降解的聚己二酸丁二醇酯(PBAT)膜,表明其具有广泛的应用潜力。重要性塑料的广泛和不分青红皂白的处置不可避免地导致环境污染。目前的填埋和焚烧方法造成的二次污染对大气造成了严重的破坏,土地,和河流。因此,微生物降解是解决塑料污染的理想途径。最近,海洋环境正在成为筛选具有潜在塑料降解能力的微生物的热点。在这项研究中,深海芽孢杆菌菌株被证明可以降解水性聚氨酯和可生物降解的PBAT膜。FAD结合氧化还原酶Oxr-1被证明是介导塑料降解的关键酶。我们的研究不仅为开发塑料降解的生物产品提供了良好的候选者,而且为研究深海微生物中塑料降解介导的碳循环铺平了道路。
Plastic wastes have been recognized as the most common and durable marine contaminants, which are not only found in the shallow water, but also on the sea floor. However, whether deep-sea microorganisms have evolved the capability of degrading plastic remains elusive. In this study, a deep-sea bacterium Bacillus velezensis GUIA was found to be capable of degrading waterborne polyurethane. Transcriptomic analysis showed that the supplement of waterborne polyurethane upregulated the expression of many genes related to spore germination, indicating that the presence of plastic had effects on the growth of strain GUIA. In addition, the supplement of waterborne polyurethane also evidently upregulated the expressions of many genes encoding lipase, protease, and
oxidoreductase. Liquid chromatography-mass spectrometry (LC-MS) results showed that potential enzymes responsible for plastic degradation in strain GUIA were identified as
oxidoreductase, protease, and lipase, which was consistent with the transcriptomic analysis. In combination of in vitro expression and degradation assays as well as Fourier transform infrared (FTIR) analysis, we demonstrated that the
oxidoreductase Oxr-1 of strain GUIA was the key degradation enzyme toward waterborne polyurethane. Moreover, the
oxidoreductase Oxr-1 was also shown to degrade the biodegradable polybutylene adipate terephthalate (PBAT) film indicating its wide application potential. IMPORTANCE The widespread and indiscriminate disposal of plastics inevitably leads to environmental pollution. The secondary pollution by current landfill and incineration methods causes serious damage to the atmosphere, land, and rivers. Therefore, microbial degradation is an ideal way to solve plastic pollution. Recently, the marine environment is becoming a hot spot to screen microorganisms possessing potential plastic degradation capabilities. In this study, a deep-sea Bacillus strain was shown to degrade both waterborne polyurethane and biodegradable PBAT film. The FAD-binding
oxidoreductase Oxr-1 was demonstrated to be the key enzyme mediating plastic degradation. Our study not only provided a good candidate for developing bio-products toward plastic degradation but also paved a way to investigate the carbon cycle mediated by plastic degradation in deep-sea microorganisms.