Naturally occurring DNA transfer system associated with membrane vesicles in cellulolytic Ruminococcus spp. of ruminal origin
Naturally occurring DNA transfer system associated with membrane vesicles in cellulolytic Ruminococcus spp. of ruminal origin
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DOI：
10.1128/aem.71.8.4248-4253.2005
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发表时间：
2005-08-01
影响因子：
4.4
通讯作者：
Mawhinney, EL
中科院分区：
文献类型：
--
作者：
Klieve, AV;Yokoyama, MT;Mawhinney, EL
一个遗传转化系统与革兰氏阴性菌报道的相似，被发现与瘤胃纤维素分解属瘤胃球菌的膜囊泡。双链DNA回收的亚细胞颗粒部分的所有纤维素分解瘤胃球菌检查。电子显微镜显示，目前唯一的颗粒类似膜囊泡。DNA与膜囊泡（也已知含有纤维素体）相关的可能性进一步得到了与亚细胞DNA相关的颗粒粘附到添加到培养物中的纤维素粉末上的支持。颗粒结合的DNA包含大小范围为< 20 -kb至49 kb（Ruminococcus sp.菌株YE 73）和23 kb至90 kb（Ruminococcus albus AR 67）的线性分子群体。从R.白色AR 67代表来源于宿主细菌基因组DNA的DNA，其具有几乎相同的HindIII消化模式和相同的16 SrRNA基因。有趣的是，颗粒相关的DNA难以用EcoRI消化，而基因组DNA易受广泛消化，这表明基因组DNA和从细胞输出的DNA存在差异限制性修饰。使用瘤胃球菌属菌株YE 71的培养物上清液的含囊泡级分的转化能够将降解结晶纤维素的能力恢复到两种突变体，否则它们不能这样做。这种能力是可以遗传的，可以传递给后代。看来，膜相关转化在复杂的微生物生态系统（如瘤胃）中的横向基因转移中起作用。
A genetic transformation system with similarities to those reported for gram-negative bacteria was found to be associated with membrane vesicles of the ruminal cellulolytic genus Ruminococcus. Double-stranded DNA was recovered from the subcellular particulate fraction of all the cellulolytic ruminococci examined. Electron microscopy revealed that the only particles present resembled membrane vesicles. The likelihood that the DNA was associated with membrane vesicles (also known to contain cellulosomes) was further supported by the adherence of the particles associated with the subcellular DNA to cellulose powder added to culture filtrates. The particle-associated DNA comprised a population of linear molecules ranging in size from < 20 -kb to 49 kb (Ruminococcus sp. strain YE73) and from 23 kb to) 90 kb (Ruminococcus albus AR67). Particle-associated DNA from R. albus AR67 represented DNA derived from genomic DNA of the host bacterium having an almost identical HindIII digestion pattern and an identical 16S rRNA gene. Paradoxically, particle-associated DNA was refractory to digestion with EcoRI, while the genomic DNA was susceptible to extensive digestion, suggesting that there is differential restriction modification of genomic DNA and DNA exported from the cell. Transformation using the vesicle-containing fraction of culture supernatant of Ruminococcus sp. strain YE71 was able to restore the ability to degrade crystalline cellulose to two mutants that were otherwise unable to do so. The ability was heritable and transferred to subsequent generations. It appears that membrane-associated transformation plays a role in lateral gene transfer in complex microbial ecosystems, such as the rumen.