Microarray and genetic analysis of electron transfer to electrodes in Geobacter sulfurreducens
Microarray and genetic analysis of electron transfer to electrodes in Geobacter sulfurreducens
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DOI：
10.1111/j.1462-2920.2006.01065.x
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发表时间：
2006-10-01
影响因子：
5.1
通讯作者：
Lovley, Derek R.
中科院分区：
文献类型：
--
作者：
Holmes, Dawn E.;Chaudhuri, Swades K.;Lovley, Derek R.
对硫还原地杆菌基因表达的全基因组分析显示，在以电极为唯一电子受体的生长过程中，474个基因的转录水平与在柠檬酸铁(III)的生长过程中存在显著差异。最大的反应是OMCs的转录水平增加了19倍以上，它编码了以前被证明是Fe(III)氧化物还原所需的外膜细胞色素。定量逆转录聚合酶链式反应和Northern分析证实，OMCs的转录本水平较高，随着发电量的增加而增加。OMCs的缺失抑制了当OMCs以反式表达时恢复的当前生产。转录表达和遗传分析表明，另一种外膜细胞色素OCEE也参与了电子向电极的传递。令人惊讶的是，其他已知在Fe(III)还原过程中起重要作用的蛋白质的基因，如外膜c型细胞色素OmcB和导电的Pilin‘纳米线’在电极上没有更高的转录水平，相关基因的缺失也不会抑制电力生产。转录组的变化表明，生长在电极上的细胞比生长在柠檬酸铁上的细胞受到更少的氧化应激，一些被注释为编码金属外排蛋白或功能未知的蛋白质的基因可能对电极上的生长起重要作用。这些结果首次表明，可以在全基因组的基础上评估生长在电极上的微生物的基因表达，从而评估其代谢状态，并表明OMCs，以及较小程度的omce，在电子到电极的转移中起着重要作用。这对电极材料的设计和微生物基因工程改善微生物燃料电池的功能具有重要意义。
Whole-genome analysis of gene expression in Geobacter sulfurreducens revealed 474 genes with transcript levels that were significantly different during growth with an electrode as the sole electron acceptor versus growth on Fe(III) citrate. The greatest response was a more than 19-fold increase in transcript levels for omcS, which encodes an outer-membrane cytochrome previously shown to be required for Fe(III) oxide reduction. Quantitative reverse transcription polymerase chain reaction and Northern analyses confirmed the higher levels of omcS transcripts, which increased as power production increased. Deletion of omcS inhibited current production that was restored when omcS was expressed in trans. Transcript expression and genetic analysis suggested that OmcE, another outer-membrane cytochrome, is also involved in electron transfer to electrodes. Surprisingly, genes for other proteins known to be important in Fe(III) reduction such as the outer-membrane c-type cytochrome, OmcB, and the electrically conductive pilin 'nanowires' did not have higher transcript levels on electrodes, and deletion of the relevant genes did not inhibit power production. Changes in the transcriptome suggested that cells growing on electrodes were subjected to less oxidative stress than cells growing on Fe(III) citrate and that a number of genes annotated as encoding metal efflux proteins or proteins of unknown function may be important for growth on electrodes. These results demonstrate for the first time that it is possible to evaluate gene expression, and hence the metabolic state, of microorganisms growing on electrodes on a genome-wide basis and suggest that OmcS, and to a lesser extent OmcE, are important in electron transfer to electrodes. This has important implications for the design of electrode materials and the genetic engineering of microorganisms to improve the function of microbial fuel cells.