Childers S E, Lovley D R
Department of Microbiology, Morrill Science Center, University of Massachusetts, Amherst, MA 01003, USA.
FEMS Microbiol Lett. 2001 Feb 20;195(2):253-8. doi: 10.1111/j.1574-6968.2001.tb10529.x.
The discovery that all hyperthermophiles that have been evaluated have the capacity to reduce Fe(III) has raised the question of whether mechanisms for dissimilatory Fe(III) reduction have been conserved throughout microbial evolution. Many studies have suggested that c-type cytochromes are integral components in electron transport to Fe(III) in mesophilic dissimilatory Fe(III)-reducing microorganisms. However, Pyrobaculum islandicum, the hyperthermophile in which Fe(III) reduction has been most intensively studied, did not contain c-type cytochromes. NADPH was a better electron donor for the Fe(III) reductase activity in P. islandicum than NADH. This is the opposite of what has been observed with mesophiles. Thus, if previous models for dissimilatory Fe(III) reduction by mesophilic bacteria are correct, then it is unlikely that a single strategy for electron transport to Fe(III) is present in all dissimilatory Fe(III)-reducing microorganisms.
所有已评估的嗜热菌都具有还原Fe(III)的能力,这一发现引发了异化性Fe(III)还原机制在整个微生物进化过程中是否保守的问题。许多研究表明,在嗜温异化性Fe(III)还原微生物中,c型细胞色素是电子传递至Fe(III)过程中的重要组成部分。然而,对Fe(III)还原进行了最深入研究的嗜热菌冰岛硫化叶菌(Pyrobaculum islandicum)并不含有c型细胞色素。对于冰岛硫化叶菌中的Fe(III)还原酶活性而言,NADPH是比NADH更好的电子供体。这与在嗜温菌中观察到的情况相反。因此,如果之前关于嗜温细菌异化性Fe(III)还原的模型是正确的,那么在所有异化性Fe(III)还原微生物中不太可能存在单一的电子传递至Fe(III)的策略。