Degradation of hexadecane by Enterobacter cloacae strain TU that secretes an exopolysaccharide as a bioemulsifier
Degradation of hexadecane by Enterobacter cloacae strain TU that secretes an exopolysaccharide as a bioemulsifier
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DOI：
10.1016/j.chemosphere.2010.05.002
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发表时间：
2010-08-01
期刊：
影响因子：
8.8
通讯作者：
Liu, Zheng
中科院分区：
文献类型：
--
作者：
Hua, Xiufu;Wu, Zuojun;Liu, Zheng
通过16 S rRNA序列分析，将先前显示利用烷烃和多环芳烃（PAH）的革兰氏阴性杆状细菌鉴定为阴沟肠杆菌（Enterobacter cloylum）（GenBank登录号，GQ 426323），并将其命名为菌株TU。在以正十六烷为唯一碳源的生长过程中，菌株TV胞外释放出一种具有生物乳化活性的胞外多糖（EPS）。发现EPS由葡萄糖和半乳糖组成，分子量为12.4 +/- 0.4 kDa。根据1D/2D NMR推测EPS的结构如下：-D-Glcp-（1 -> 3）-alpha-D-GlcpAc-（1 -> 3）-alpha-D-Galp-（1 -> 4）EPS的浓度对正十六烷的乳化作用和水相分配有促进作用，但EPS的浓度对正十六烷的zeta电位有中和作用。通过微生物粘附碳氢化合物测定法（MATH）测定，ClobaltTV细胞的表面疏水性增加。当正十六烷作为大肠杆菌的唯一碳源时，这有利于正十六烷的生物利用度。Closophy TV，从而促进了这种烃的加速降解。(C)2010爱思唯尔有限公司版权所有。
A Gram-negative rod-shaped bacterium, previously shown to utilize alkanes and polycyclic aromatic hydrocarbons (PAHs), was identified as Enterobacter cloacae (GenBank accession number, GQ426323) by 16S rRNA sequence analysis and was designated as strain TU. During growing on n-hexadecane as the sole carbon source, the strain TV extracellularly released an exopolysaccharide (EPS) exhibiting bio-emulsifying activity into the surrounding medium. The EPS was found to be composed of glucose and galactose with molecular weight of 12.4 +/- 0.4 kDa. The structure of the EPS was postulated according to by 1D/2D NMR, as follows: -D-Glcp-(1 -> 3)-alpha-D-GlcpAc-(1 -> 3)-alpha-D-Galp-(1 -> 4)-alpha-D-Galp-(1 ->. While an enhanced emulsification and aqueous partitioning of n-hexadecane was displayed as functions of the EPS concentration, the EPS neutralized the zeta potential of E. cloacae TV cell and elevated the surface hydrophobicity of the cells, as determined by the microorganisms adhering to hydrocarbon assay (MATH). This was found to favor the bioavailability of n-hexadecane when it served as the sole carbon source for E. cloacae TV and thereby contributed to the accelerated degradation of this hydrocarbon. (C) 2010 Elsevier Ltd. All rights reserved.