Centre for Biomolecular Sciences, School of Molecular Medical Sciences, University Park, University of Nottingham, Nottingham NG7 2RD, United Kingdom.
J Bacteriol. 2010 Feb;192(3):657-64. doi: 10.1128/JB.01209-09. Epub 2009 Nov 20.
Clostridium difficile is the major cause of infectious diarrhea and a major burden to health care services. The ability of this organism to form endospores plays a pivotal role in infection and disease transmission. Spores are highly resistant to many forms of disinfection and thus are able to persist on hospital surfaces and disseminate infection. In order to cause disease, the spores must germinate and the organism must grow vegetatively. Spore germination in Bacillus is well understood, and genes important for this process have recently been identified in Clostridium perfringens; however, little is known about C. difficile. Apparent homologues of the spore cortex lytic enzyme genes cwlJ and sleB (Bacillus subtilis) and sleC (C. perfringens) are present in the C. difficile genome, and we describe inactivation of these homologues in C. difficile 630Delta erm and a B1/NAP1/027 clinical isolate. Spores of a sleC mutant were unable to form colonies when germination was induced with taurocholate, although decoated sleC spores formed the same number of heat-resistant colonies as the parental control, even in the absence of germinants. This suggests that sleC is absolutely required for conversion of spores to vegetative cells, in contrast to CD3563 (a cwlJ/sleB homologue), inactivation of which had no effect on germination and outgrowth of C. difficile spores under the same conditions. The B1/NAP1/027 strain R20291 was found to sporulate more slowly and produce fewer spores than 630Delta erm. Furthermore, fewer R20291 spores germinated, indicating that there are differences in both sporulation and germination between these epidemic and nonepidemic C. difficile isolates.
艰难梭菌是感染性腹泻的主要原因，也是医疗保健服务的主要负担。该生物体形成芽孢的能力在感染和疾病传播中起着关键作用。芽孢对许多形式的消毒具有高度抗性，因此能够在医院表面存活并传播感染。为了引起疾病，孢子必须发芽，并且生物体必须生长为营养体。芽孢在芽孢杆菌中的发芽过程已得到很好的理解，并且最近在产气荚膜梭菌中确定了对该过程重要的基因；然而，关于艰难梭菌知之甚少。在艰难梭菌基因组中存在与孢子皮层溶酶基因 cwlJ 和 sleB（枯草芽孢杆菌）和 sleC（产气荚膜梭菌）明显同源的基因，我们描述了在艰难梭菌 630Delta erm 和 B1/NAP1/027 临床分离株中这些同源物的失活。尽管脱壳的 sleC 孢子在没有发芽剂的情况下形成与亲本对照相同数量的耐热菌落，但 sleC 突变体的孢子在用牛磺胆酸钠诱导发芽时无法形成菌落。这表明 sleC 绝对需要将孢子转化为营养细胞，与 CD3563（cwlJ/sleB 同源物）形成对比，在相同条件下，失活 CD3563 对艰难梭菌孢子的发芽和生长没有影响。发现 B1/NAP1/027 菌株 R20291 的孢子形成速度较慢，产生的孢子数量也较少，而 630Delta erm 则较少。此外，R20291 的孢子发芽较少，这表明这些流行和非流行艰难梭菌分离株在孢子形成和发芽方面存在差异。
