Detection Department, Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire, SP4 0JQ, UK,
Curr Microbiol. 2014 Apr;68(4):477-85. doi: 10.1007/s00284-013-0502-7. Epub 2013 Dec 6.
Transposon-directed insertion site sequencing was used to identify genes required by Bacillus thuringiensis to survive in non-axenic plant/soil microcosms. A total of 516 genetic loci fulfilled the criteria as conferring survival characteristics. Of these, 127 (24.6 %) were associated with uptake and transport systems; 227 loci (44.0 %) coded for enzymatic properties; 49 (9.5 %) were gene regulation or sensory loci; 40 (7.8 %) were structural proteins found in the cell envelope or had enzymatic activities related to it and 24 (4.7 %) were involved in the production of antibiotics or resistance to them. Eighty-three (16.1 %) encoded hypothetical proteins or those of unknown function. The ability to form spores was a key survival characteristic in the microcosms: bacteria, inoculated in either spore or vegetative form, were able to multiply and colonise the soil, whereas a sporulation-deficient mutant was not. The presence of grass seedlings was critical to colonisation. Bacteria labelled with green fluorescent protein were observed to adhere to plant roots. The sporulation-specific promoter of spo0A, the key regulator of sporulation, was strongly activated in the rhizosphere. In contrast, the vegetative-specific promoters of spo0A and PlcR, a pleiotropic regulator of genes with diverse activities, were only very weakly activated.
转座子导向插入位点测序被用于鉴定苏云金芽孢杆菌在非无菌植物/土壤微宇宙中生存所需的基因。共有 516 个遗传基因座符合赋予生存特征的标准。其中，127 个（24.6%）与摄取和运输系统有关；227 个基因座（44.0%）编码酶特性；49 个（9.5%）是基因调控或感觉基因座；40 个（7.8%）是存在于细胞包膜中的结构蛋白或与其具有酶活性相关的蛋白，24 个（4.7%）与抗生素的产生或对其的抗性有关。83 个（16.1%）编码假设蛋白或未知功能的蛋白。在微宇宙中，形成孢子的能力是关键的生存特征：接种在孢子或营养体形式的细菌能够繁殖并定殖土壤，而缺乏孢子形成能力的突变体则不能。草苗的存在对定殖至关重要。用绿色荧光蛋白标记的细菌被观察到附着在植物根部。孢子形成特异性启动子 spo0A 的存在，是孢子形成的关键调节因子，在根际中被强烈激活。相比之下，spooA 和 PlcR 的营养体特异性启动子（多效调节因子，调节具有多种活性的基因）仅被非常弱地激活。
