Post Graduate Department of Biotechnology, Ayya Nadar Janaki Ammal College (Autonomous), Affiliated to Madurai Kamaraj University, Sivakasi, 626124, Tamil Nadu, India.
Post Graduate and Research Department of Biotechnology, Jamal Mohamed College (Autonomous), Affiliated to Bharathidasan University, Tiruchirappalli, 620020, Tamil Nadu, India.
Environ Res. 2024 Jun 15;251(Pt 1):118631. doi: 10.1016/j.envres.2024.118631. Epub 2024 Mar 5.
Plastic waste has become a global issue and a threat to the ecosystem. The present study isolated polyurethane (PU) degrading bacterial species from soil dumped with plastic wastes. Four bacterial isolates, RS1, RS6, RS9 and RS13 were obtained and their ability to degrade PU in a synthetic medium with PU as a sole source of carbon was assessed individually. After thirty days of incubation, the highest PU weight loss of 67.36 ± 0.32% was recorded in the medium containing RS13 isolate. The results of FTIR revealed the occurrence of carbonyl peaks. The putative isolate RS13 confirmed with the genus Moraxella according to 16S rRNA gene sequencing and the isolate was specified as Moraxella catarrhalis strain BMPPS3. The restriction analysis of Moraxella catarrhalis strain BMPPS3 revealed that the GCAT content to 51% and 49% correspondingly. Moraxella catarrhalis strain BMPPS3 was able to colonize on PU surface and form a biofilm as revealed by SEM investigation. Fatty acids and alkanes were found to be the degradation products by GC-MS analysis. The presence of these metabolites facilitated the growth of strain RS13 and suggested that ester hydrolysis products had been mineralized into CO and HO. Extracellular biosurfactant synthesis has also been found in Moraxella catarrhalis strain BMPPS13 inoculated with synthetic media and mineral salt media containing PU and glucose as carbon sources, respectively with a significant level of cell-surface hydrophobicity (32%). The production and activity of extracellular esterase showed consistent increase from day 1-15 which peaked (1.029 mM/min/mg) on day 24 significantly at P < 0.001. Crude biosurfactants were lipopeptide-based, according to the characteristic investigation. According to this study findings, Moraxella catarrhalis produces biosurfactants of the esterase, urethanase and lipase (lipopeptide) types when carbon source PU is present.
塑料废物已成为全球性问题，对生态系统构成威胁。本研究从倾倒塑料废物的土壤中分离出了聚氨酯（PU）降解细菌。获得了 4 个细菌分离株 RS1、RS6、RS9 和 RS13，并分别评估了它们在以 PU 为唯一碳源的合成培养基中降解 PU 的能力。在 30 天的孵育后，在含有 RS13 分离株的培养基中记录到最高的 PU 重量损失为 67.36 ± 0.32%。FTIR 的结果显示羰基峰的出现。根据 16S rRNA 基因测序，推测的分离株 RS13 被确认为莫拉氏菌属 Moraxella catarrhalis 菌株 BMPPS3。Moraxella catarrhalis 菌株 BMPPS3 的限制分析显示 GCAT 含量分别为 51%和 49%。扫描电子显微镜（SEM）研究表明，Moraxella catarrhalis 菌株 BMPPS3 能够在 PU 表面定植并形成生物膜。通过 GC-MS 分析发现脂肪酸和烷烃是降解产物。这些代谢物的存在促进了 RS13 菌株的生长，并表明酯水解产物已矿化为 CO 和 HO。在含有 PU 和葡萄糖作为碳源的合成培养基和无机盐培养基中接种 Moraxella catarrhalis 菌株 BMPPS13 时，也发现了细胞外生物表面活性剂的合成，并且细胞表面疏水性有显著提高（32%）。胞外酯酶的产生和活性从第 1 天到第 15 天持续增加，第 24 天达到峰值（1.029 mM/min/mg），P 值<0.001。根据特征研究，粗生物表面活性剂基于脂肽。根据本研究结果，当存在碳源 PU 时，莫拉氏菌产生酯酶、尿酶和脂肪酶（脂肽）类型的生物表面活性剂。
