Characterization of extracellular DNA production and flocculation of the marine photosynthetic bacterium Rhodovulum sulfidophilum
Characterization of extracellular DNA production and flocculation of the marine photosynthetic bacterium Rhodovulum sulfidophilum
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DOI：
10.1007/s00253-009-2031-7
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发表时间：
2009-08-01
影响因子：
5
通讯作者：
Kikuchi, Yo
中科院分区：
文献类型：
--
作者：
Suzuki, Hiromichi;Daimon, Masahide;Kikuchi, Yo
海洋光合细菌Rhodovulum sulfidophilum产生参与其絮凝的胞外核酸。以前，我们表明，这些细胞外核酸释放到培养基中的RNA部分主要含有非氨酰化的完全成熟大小的tRNA和片段的16 S和23 S rRNA。在这里，我们报告的表征细胞外DNA本身及其生产过程中的培养。Southern杂交结果表明，胞内DNA和胞外可溶性DNA的核苷酸序列无差异。整个细胞内DNA似乎从细胞中释放出来。细菌絮体被脱氧核糖核酸酶或核糖核酸酶降解，表明絮体中至少有胞外DNA和RNA参与絮体的维持。当在营养丰富的培养基中培养时，细菌形成小絮凝物并产生大量的胞外DNA，其溶解在培养基中。然而，在营养不良的培养基中，出现了巨大的细胞絮团，并且在培养基中几乎没有观察到胞外可溶性DNA。由于絮凝物被脱氧核糖核酸酶处理降解，因此在富培养基中观察到的细胞外可溶性DNA可能被掺入到大絮凝物中，并在贫培养基中维持絮凝物中发挥作用。此外，抑制剂的群体感应，α-环糊精，抑制巨大的絮凝体的维护营养不良的介质。在α-环糊精的存在下，絮体迅速降解，胞外可溶性DNA的产量增加。
The marine photosynthetic bacterium Rhodovulum sulfidophilum produces extracellular nucleic acids involved in its flocculation. Previously, we showed that the RNA fraction of these extracellular nucleic acids released into the culture medium contains mainly non-aminoacylated fully mature-sized tRNAs and fragments of 16S and 23S rRNAs. Here, we report the characterization of extracellular DNA itself and its production during cultivation. No differences were detected in nucleotide sequence between the intracellular DNA and extracellular soluble DNA on Southern blotting. Whole intracellular DNA seemed to be released from the cell. The bacterial floc was degraded by deoxyribonuclease or ribonuclease treatment, indicating that at least the extracellular DNA and RNAs in the floc are involved in the maintenance of the floc. When cultivated in nutritionally rich medium, the bacteria formed small flocs and produced large amounts of extracellular DNA, which were solubilized in the medium. In nutritionally poor medium, however, huge flocs of cells appeared and almost no extracellular soluble DNA was observed in the medium. As the floc was degraded by deoxyribonuclease treatment, it seems likely that the extracellular soluble DNA observed in the rich medium may be incorporated into the large floc and play a role in floc maintenance in poor medium. Addition of an inhibitor of quorum sensing, alpha-cyclodextrin, inhibited huge floc maintenance in the nutritionally poor medium. In the presence of alpha-cyclodextrin, the floc was rapidly degraded and extracellular soluble DNA production increased.