Isolation and Characterization of Superdormant Spores of Bacillus Species
Isolation and Characterization of Superdormant Spores of Bacillus Species
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DOI：
10.1128/jb.01668-08
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发表时间：
2009-03-15
影响因子：
3.2
通讯作者：
Setlow, Peter
中科院分区：
文献类型：
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作者：
Ghosh, Sonali;Setlow, Peter
枯草芽孢杆菌（Bacillus subtilis）和巨芽孢杆菌（Bacillus megaterium）的超休眠孢子在高营养水平激活一个或两个发芽受体后萌发，产量为4%至12%。这些超级休眠孢子不与初始营养物质或刺激其他发芽受体的营养物质一起发芽，并且超级休眠孢子的缺陷不是遗传的。然而，超休眠孢子确实与Ca2(+)-二吡啶酸或十二胺一起发芽。虽然这些超级休眠孢子在激活一个或两个营养生发受体的高水平营养物质下不能发芽，但它们在激活更多受体的营养混合物中发芽，使用高水平的营养混合物激活更多的生发受体会降低超级休眠孢子的产量。采用中等营养水平分离超休眠孢子可提高产量；所得到的孢子在初始的中等营养浓度下萌发较差，但在高营养浓度下萌发良好。这些发现表明，种群中超休眠孢子的水平取决于所使用的萌发条件，当使用较好的萌发条件时，分离出的超休眠孢子较少。这些发现进一步表明，与种群中的大多数孢子相比，超休眠孢子需要增加的信号来触发孢子萌发。决定一个孢子是否处于超休眠状态的一个因素是它的萌发受体水平，因为萌发受体水平较高的孢子群体产生的超休眠孢子水平较低。第二个重要因素可能是孢子群体的热活化，因为非热活化孢子群体的超休眠孢子产量高于最佳活化孢子的产量。
Superdormant spores of Bacillus subtilis and Bacillus megaterium were isolated in 4 to 12% yields following germination with high nutrient levels that activated one or two germinant receptors. These superdormant spores did not germinate with the initial nutrients or those that stimulated other germinant receptors, and the superdormant spores' defect was not genetic. The superdormant spores did, however, germinate with Ca2(+)-dipicolinic acid or dodecylamine. Although these superdormant spores did not germinate with high levels of nutrients that activated one or two nutrient germinant receptors, they germinated with nutrient mixtures that activated more receptors, and using high levels of nutrient mixtures activating more germinant receptors decreased superdormant spore yields. The use of moderate nutrient levels to isolate superdormant spores increased their yields; the resultant spores germinated poorly with the initial moderate nutrient concentrations, but they germinated well with high nutrient concentrations. These findings suggest that the levels of superdormant spores in populations depend on the germination conditions used, with fewer superdormant spores isolated when better germination conditions are used. These findings further suggest that superdormant spores require an increased signal for triggering spore germination compared to most spores in populations. One factor determining whether a spore is superdormant is its level of germinant receptors, since spore populations with higher levels of germinant receptors yielded lower levels of superdormant spores. A second important factor may be heat activation of spore populations, since yields of superdormant spores from non-heat-activated spore populations were higher than those from optimally activated spores.