Department of Botany, School of Life Sciences, Bharathidasan University, Tiruchirappalli, Tamil Nadu, 620 024, India.
CAS in Botany, University of Madras, Chennai, Tamil Nadu, 600025, India.
Sci Rep. 2024 Apr 9;14(1):8351. doi: 10.1038/s41598-024-59032-4.
Plastic accumulation is a severe threat to the environment due to its resistivity to thermal, mechanical and biological processes. In recent years, microbial degradation of plastic waste disposal is of interest because of its eco-friendly nature. In this study, a total of 33 fungi were isolated from the plastisphere and out of which 28 fungal species showed halo zone of clearance in agarized LDPE media. The fungus showing highest zone of clearance was further used to evaluate its degradation potential. Based on morphological and molecular technique, the fungus was identified as Cladosporium sphaerospermum. The biodegradation of LDPE by C. sphaerospermum was evaluated by various methods. The exposure of LDPE with C. sphaerospermum resulted in weight loss (15.23%) in seven days, higher reduction rate (0.0224/day) and lower half-life (30.93 days). FTIR analysis showed changes in functional group and increased carbonyl index in LDPE treated with C. sphaerospermum. SEMimages evidenced the formation of pits, surface aberrations and grooves on the LDPE film treated with the fungus whereas the untreated control LDPE film showed no change. AFM analysis confirmed the surface changes and roughness in fungus treated LDPE film. This might be due to the extracellular lignolytic enzymes secreted by C. sphaerospermum grown on LDPE. The degradation of polyethylene by Short chain alkanes such as dodecane, hexasiloxane and silane were identified in the extract of fungus incubated with LDPE film through GC-MS analysis which might be due to the degradation of LDPE film by C. sphaerospermum. This was the first report on the LDPE degradation by C. sphaerospermum in very short duration which enables green scavenging of plastic wastes.
塑料积累因其对热、机械和生物过程的抵抗力而对环境构成严重威胁。近年来，由于其环保性质，微生物降解塑料废物处理引起了人们的兴趣。在这项研究中，从塑料表面共分离出 33 株真菌，其中 28 株真菌在琼脂化 LDPE 培养基中显示出清晰的晕圈。显示最高清除带的真菌进一步用于评估其降解潜力。根据形态学和分子技术，该真菌被鉴定为枝孢属（Cladosporium）。通过各种方法评估了 C. sphaerospermum 对 LDPE 的生物降解。将 LDPE 与 C. sphaerospermum 一起暴露导致 LDPE 在七天内失重（15.23%），更高的还原率（0.0224/天）和更短的半衰期（30.93 天）。FTIR 分析表明，LDPE 经 C. sphaerospermum 处理后，功能基团发生变化，羰基指数增加。SEM 图像表明，在 LDPE 薄膜上形成了凹坑、表面变形和凹槽，而未经处理的对照 LDPE 薄膜则没有变化。AFM 分析证实了经真菌处理的 LDPE 薄膜的表面变化和粗糙度。这可能是由于 C. sphaerospermum 在 LDPE 上生长时分泌的细胞外木质素酶所致。通过 GC-MS 分析，在与 LDPE 薄膜孵育的真菌提取物中鉴定出短链烷烃（如十二烷、六硅氧烷和硅烷）对聚乙烯的降解，这可能是由于 C. sphaerospermum 对 LDPE 薄膜的降解所致。这是枝孢属在极短时间内降解 LDPE 的首次报道，这使得塑料废物的绿色清除成为可能。
