Abstract

Accumulation of plastic waste has become an environmental threat and a global problem. In this research, polyethylene degrading ligninolytic bacteria were isolated from plastic waste polluted soil. Two bacterial isolates, namely PE2 and PE3 have been obtained from the soil samples. Polyethylene degrading ability of the isolates has been assessed individually in a synthetic media containing polyethylene as a carbon source. The results indicated that maximum weight reduction of polyethylene (6.68%) was found in PE3 inoculated media after thirty days of incubation. Fourier Transform Infrared Spectroscopic results showed the appearance of carbonyl peaks. 16S rRNA gene sequencing studies revealed that the potential isolate PE3 belongs to the genus Bacillus and it was named Bacillus sp. strain PE3. From the scanning electron microscopic results, it is inferred that Bacillus sp. strain PE3 could colonize on the polyethylene surface and form a biofilm. Besides, the viable Bacillus sp. strain PE3 on polyethylene surface was confirmed by fluorescence microscopic analysis. Alkanes and fatty acids were identified in the degraded products by gas chromatography-mass spectrometer analysis. From the results of native polyacrylamide gel electrophoresis, the activities of laccase and lignin peroxidase were noticed. Furthermore, extracellular production of biosurfactant has been observed in the Bacillus sp. strain PE3 inoculated mineral salt media and synthetic media with glucose and polyethylene as the carbon source respectively. The characterization studies of crude biosurfactant have confirmed that lipopeptide nature biosurfactant. The present study demonstrates that the ligninolytic enzymes laccase, lignin peroxidase, and lipopeptide type biosurfactant are produced by Bacillus sp. strain PE3 in the media with polyethylene as a carbon source.

Graphic abstract

中文翻译：

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生产生物表面活性剂木质素分解菌对聚乙烯降解的评价

摘要

塑料废物的积累已成为环境威胁和全球性问题。本研究从塑料垃圾污染的土壤中分离出聚乙烯降解木质素分解菌。从土壤样品中获得了两种细菌分离物，即 PE2 和 PE3。已在含有聚乙烯作为碳源的合成培养基中单独评估了分离物的聚乙烯降解能力。结果表明，在培养 30 天后，在 PE3 接种的培养基中发现聚乙烯的最大重量减少 (6.68%)。傅里叶变换红外光谱结果显示羰基峰的出现。16S rRNA基因测序研究表明，潜在分离株PE3属于芽孢杆菌属，命名为芽孢杆菌sp. 菌株 PE3 。从扫描电子显微镜结果推断，芽孢杆菌属。PE3菌株可以在聚乙烯表面定殖并形成生物膜。此外，可行的芽孢杆菌属。通过荧光显微分析证实了聚乙烯表面上的菌株PE3。通过气相色谱-质谱分析在降解产物中鉴定出烷烃和脂肪酸。天然聚丙烯酰胺凝胶电泳结果显示漆酶和木质素过氧化物酶的活性。此外，已经在芽孢杆菌中观察到生物表面活性剂的细胞外产生。sp. PE3菌株分别接种以葡萄糖和聚乙烯为碳源的矿物盐培养基和合成培养基。粗生物表面活性剂的表征研究证实了脂肽性质的生物表面活性剂。本研究表明，木质素降解酶漆酶，木质素过氧化物酶，和脂肽类生物表面活性剂所生产的芽孢杆菌属。在以聚乙烯为碳源的培养基中过滤 PE3。

图形摘要