Department of Microbiology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, 45320, Pakistan.
Biodegradation. 2013 Nov;24(6):865-77. doi: 10.1007/s10532-013-9634-5. Epub 2013 Mar 28.
A polyurethane (PU) degrading bacterial strain MZA-75 was isolated from soil through enrichment technique. The bacterium was identified through 16S rRNA gene sequencing, the phylogenetic analysis indicated the strain MZA-75 belonged to genus Bacillus having maximum similarity with Bacillus subtilis strain JBE0016. The degradation of PU films by strain MZA-75 in mineral salt medium (MSM) was analyzed by scanning electron microscopy (SEM), fourier transform infra-red spectroscopy (FT-IR) and gel permeation chromatography (GPC). SEM revealed the appearance of widespread cracks on the surface. FTIR spectrum showed decrease in ester functional group. Increase in polydispersity index was observed in GPC, which indicates chain scission as a result of microbial treatment. CO2 evolution and cell growth increased when PU was used as carbon source in MSM in Sturm test. Increase in both cell associated and extracellular esterases was observed in the presence of PU indicated by p-Nitrophenyl acetate (pNPA) hydrolysis assay. Analysis of cell free supernatant by gas chromatography-mass spectrometry (GC-MS) revealed that 1,4-butanediol and adipic acid monomers were produced. Bacillus subtilis strain MZA-75 can degrade the soft segment of polyester polyurethane, unfortunately no information about the fate of hard segment could be obtained. Growth of strain MZA-75 in the presence of these metabolites indicated mineralization of ester hydrolysis products into CO2 and H2O.
从土壤中通过富集技术分离到一种可降解聚氨酯（PU）的细菌菌株 MZA-75。通过 16S rRNA 基因测序对该细菌进行鉴定，系统发育分析表明，菌株 MZA-75 属于芽孢杆菌属，与枯草芽孢杆菌 JBE0016 具有最大相似性。通过扫描电子显微镜（SEM）、傅里叶变换红外光谱（FT-IR）和凝胶渗透色谱（GPC）分析了菌株 MZA-75 在无机盐培养基（MSM）中对 PU 薄膜的降解作用。SEM 显示表面出现广泛的裂纹。FTIR 谱显示酯官能团减少。GPC 中观察到多分散指数增加，表明微生物处理导致链断裂。在 Sturm 试验中，当将 PU 用作 MSM 中的碳源时，CO2 释放和细胞生长增加。在存在 PU 的情况下，通过 p-硝基苯乙酸酯（pNPA）水解试验观察到细胞相关和细胞外酯酶增加，表明存在 PU。通过气相色谱-质谱联用（GC-MS）分析无细胞上清液表明生成了 1,4-丁二醇和己二酸单体。枯草芽孢杆菌 MZA-75 可以降解聚酯型聚氨酯的软段，然而，关于硬段的命运，我们无法获得更多信息。在这些代谢物存在的情况下，MZA-75 菌株的生长表明酯水解产物矿化为 CO2 和 H2O。
