Key Lab of Plant Biotechnology in Universities of Shandong Province, College of Life Science, Qingdao Agricultural University, Qingdao, China.
CAS and Shandong Province Key Laboratory of Experimental Marine Biology & Center of Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
Microbiol Spectr. 2023 Jun 15;11(3):e0007323. doi: 10.1128/spectrum.00073-23. Epub 2023 Mar 30.
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 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. 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 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.
塑料废物已被确认为最常见和最持久的海洋污染物，它们不仅存在于浅水区，还存在于海底。然而，深海微生物是否已经进化出降解塑料的能力仍不得而知。在这项研究中，发现一种深海细菌 Bacillus velezensis GUIA 能够降解水性聚氨酯。转录组分析表明，水性聚氨酯的补充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 GUIA 菌株的生长有影响。此外，水性聚氨酯的补充还明显上调了许多编码脂肪酶、蛋白酶和氧化还原酶的基因的表达。液相色谱-质谱 (LC-MS) 结果表明，GUIA 菌株中负责塑料降解的潜在酶被鉴定为氧化还原酶、蛋白酶和脂肪酶，这与转录组分析结果一致。通过表达和降解试验以及傅里叶变换红外 (FTIR) 分析，我们证明了 GUIA 菌株的氧化还原酶 Oxr-1 是水性聚氨酯的关键降解酶。此外，氧化还原酶 Oxr-1 还被证明可以降解可生物降解的聚对苯二甲酸丁二醇酯 (PBAT) 薄膜，表明其具有广泛的应用潜力。塑料的广泛和无差别丢弃不可避免地导致了环境污染。目前垃圾填埋和焚烧方法造成的二次污染对大气、土地和河流造成了严重破坏。因此，微生物降解是解决塑料污染的理想方法。最近，海洋环境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，一种深海菌株被证明可以降解水性聚氨酯和可生物降解的 PBAT 薄膜。黄素腺嘌呤二核苷酸 (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用于塑料降解的生物制品提供了一个良好的候选物，也为研究深海微生物介导的塑料降解碳循环铺平了道路。
