Department of Biological Sciences, Southeastern Louisiana University, SLU 10736, Hammond, LA 70402, USA.
Biodegradation. 2012 Jul;23(4):561-73. doi: 10.1007/s10532-011-9533-6. Epub 2012 Jan 7.
A soil microorganism, designated as P7, was characterized and investigated for its ability to degrade polyurethane (PU). This bacterial isolate was identified as Acinetobacter gerneri on the basis of 16 s rRNA sequencing and biochemical phenotype analysis. The ability of this organism to degrade polyurethane was characterized by the measurement of growth, SEM observation, measurement of electrophoretic mobility and the purification and characterization of a polyurethane degrading enzyme. The purified protein has a molecular weight of approximately 66 kDa as determined by SDS-PAGE. Substrate specificity was examined using p-nitrophenyl substrates with varying carbon lengths. The highest substrate specificity was observed using p-nitrophenyl-propanate with an activity of 37.58 ± 0.21 U mg(-1). Additionally, the enzyme is inhibited by phenylmethylsulfonylfluoride and by ethylenediamine-tetra acetic acid. When grown on Impranil DLN(™) YES medium, a lag phase was noted for the first 3 h which was followed by logarithmic growth for 5 h. For the linear portion of growth between 5 and 9 h, a μ value of 0.413 doublings h(-1) was calculated. After 9 h of incubation the cell number dramatically decreased resulting in a chalky precipitate. Measurements of electrophoretic mobility indicated the formation of a complex between the PU and A. gerneri P7 cells. A hybrid zeta potential had been generated between the cells and polyurethane. Further evidence for a complex was provided by SEM observation where cells appeared to cluster along the surface of polyurethane particles and along edges of polyurethane films. Occasionally, the cells established an anchor-like structure that connected the cells to polyurethane particles.
一种土壤微生物，被命名为 P7，因其降解聚氨酯（PU）的能力而被描述和研究。该细菌分离株基于 16S rRNA 测序和生化表型分析，被鉴定为不动杆菌属。该生物体降解聚氨酯的能力通过测量生长、SEM 观察、电泳迁移率的测量以及聚氨酯降解酶的纯化和表征来表征。通过 SDS-PAGE 确定，纯化的蛋白质分子量约为 66 kDa。使用不同碳长的 p-硝基苯底物检查了底物特异性。使用 p-硝基苯丙酸盐观察到最高的底物特异性，其活性为 37.58±0.21 U mg(-1)。此外，该酶被苯甲基磺酰氟和乙二胺四乙酸抑制。当在 Impranil DLN(™) YES 培养基上生长时，首先注意到在最初的 3 小时内有一个停滞期，然后是 5 小时的对数生长期。对于 5 至 9 小时之间的线性生长部分，计算出μ值为 0.413 个倍增 h(-1)。孵育 9 小时后，细胞数量急剧减少，导致形成白垩状沉淀物。电泳迁移率的测量表明形成了 PU 和 A. gerneri P7 细胞之间的复合物。在细胞和聚氨酯之间产生了混合的动电电位。SEM 观察进一步提供了复合物的证据，其中细胞似乎沿着聚氨酯颗粒的表面和聚氨酯薄膜的边缘聚集。偶尔，细胞建立了类似于锚的结构，将细胞连接到聚氨酯颗粒上。
