Department of Biochemistry, Physiology and Microbiology, Laboratory of Protein Biochemistry and Protein Engineering, Ghent University, Ghent, Belgium.
Microb Biotechnol. 2008 Jan;1(1):40-52. doi: 10.1111/j.1751-7915.2007.00005.x.
Many studies have reported microorganisms as efficient biocatalysts for colour removal of dye-containing industrial wastewaters. We present the first comprehensive study to identify all molecular components involved in decolorization by bacterial cells. Mutants from the model organism Shewanella oneidensis MR-1, generated by random transposon and targeted insertional mutagenesis, were screened for defects in decolorization of an oxazine and diazo dye. We demonstrate that decolorization is an extracellular reduction process requiring a multicomponent electron transfer pathway that consists of cytoplasmic membrane, periplasmic and outer membrane components. The presence of melanin, a redox-active molecule excreted by S. oneidensis, was shown to enhance the dye reduction rates. Menaquinones and the cytochrome CymA are the crucial cytoplasmic membrane components of the pathway, which then branches off via a network of periplasmic cytochromes to three outer membrane cytochromes. The key proteins of this network are MtrA and OmcB in the periplasm and outer membrane respectively. A model of the complete dye reduction pathway is proposed in which the dye molecules are reduced by the outer membrane cytochromes either directly or indirectly via melanin.
许多研究报告称微生物是去除含染料工业废水颜色的有效生物催化剂。我们首次进行了一项全面的研究，以确定细菌细胞脱色所涉及的所有分子组成部分。通过随机转座子和靶向插入诱变，从模式生物希瓦氏菌 MR-1 中生成的突变体，针对吖嗪和重氮染料的脱色缺陷进行了筛选。我们证明，脱色是一种需要多组分电子转移途径的细胞外还原过程，该途径由细胞质膜、周质和外膜组成。希瓦氏菌分泌的一种氧化还原活性分子黑色素的存在被证明可以提高染料的还原速率。甲萘醌和细胞色素 CymA 是该途径的关键细胞质膜成分，然后通过周质细胞色素网络分支为三种外膜细胞色素。该网络的关键蛋白分别是周质中的 MtrA 和外膜中的 OmcB。提出了一个完整的染料还原途径模型，其中染料分子通过外膜细胞色素直接或间接地通过黑色素还原。
