Santos Fernando, Meyerdierks Anke, Peña Arantxa, Rosselló-Mora Ramon, Amann Rudolf, Antón Josefa
División de Microbiología, Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03080 Alicante, Spain.
Environ Microbiol. 2007 Jul;9(7):1711-23. doi: 10.1111/j.1462-2920.2007.01289.x.
Hypersaline environments, such as crystallizer ponds of solar salterns, show one of the highest concentration of viruses reported for aquatic systems. All the halophages characterized so far are isolates obtained by cultivation from described haloarchaeal species that have only low abundance in the environment. We employed a culture-independent metagenomic approach to analyse for the first time complete genomes in the halophage community and explored the in situ diversity by transmission electron microscopy and pulsed-field gel electrophoresis. We report the genomic sequence of a not yet isolated halophage (named as environmental halophage 1 'EHP-1') whose DNA was obtained from crystallizer samples with a salinity of 31%. The sequenced genome has a size of 35 kb and a G + C content around 51%. The G + C content is lower than that of previously characterized halophages. However, G + C content and codon usage in EHP-1 are similar to the recently cultivated and sequenced Haloquadratum walsbyi, the major prokaryotic component in solar salterns around the world. Forty open reading frames have been predicted, including genes that putatively code for proteins involved in DNA replication (ribonucleotide reductases, thymidylate kinase) normally found in lytic viruses.
高盐环境，如太阳能盐场的结晶池，是已报道的水生系统中病毒浓度最高的环境之一。到目前为止，所有已鉴定的嗜盐噬菌体都是从环境中丰度较低的特定嗜盐古菌物种中通过培养分离得到的。我们采用了一种不依赖培养的宏基因组学方法，首次分析了嗜盐噬菌体群落中的完整基因组，并通过透射电子显微镜和脉冲场凝胶电泳探索了其原位多样性。我们报告了一种尚未分离的嗜盐噬菌体（命名为环境嗜盐噬菌体1，即“EHP - 1”）的基因组序列，其DNA是从盐度为31%的结晶器样品中获得的。测序得到的基因组大小为35 kb，G + C含量约为51%。该G + C含量低于先前鉴定的嗜盐噬菌体。然而，EHP - 1中的G + C含量和密码子使用情况与最近培养并测序的沃氏嗜盐四方体（Haloquadratum walsbyi）相似，沃氏嗜盐四方体是全球太阳能盐场中的主要原核生物成分。已预测出40个开放阅读框，包括可能编码参与DNA复制的蛋白质（核糖核苷酸还原酶、胸苷酸激酶）的基因，这些基因通常在裂解性病毒中发现。
