Centre for Microbial Ecology and Genomics, University of Pretoria, Pretoria, South Africa.
Environ Microbiol. 2015 Feb;17(2):480-95. doi: 10.1111/1462-2920.12528. Epub 2014 Jul 7.
Hypolithic microbial communities are specialized desert communities inhabiting the underside of translucent rocks. Here, we present the first study of the viral fraction of these communities isolated from the hyperarid Namib Desert. The taxonomic composition of the hypolithic viral communities was investigated and a functional assessment of the sequences determined. Phylotypic analysis showed that bacteriophages belonging to the order Caudovirales, in particular the family Siphoviridae, were most prevalent. Functional analysis and comparison with other metaviromes revealed a relatively high frequency of cell wall-degrading enzymes, ribonucleotide reductases (RNRs) and phage-associated genes. Phylogenetic analyses of terL and phoH marker genes indicated that many of the sequences were novel and distinct from known isolates, and the class distribution of the RNRs suggests that this is a novel environment. The composition of the viral hypolith fraction containing many Bacillus-infecting phages was not completely consistent with Namib hypolith phylotypic surveys of the bacterial hosts, in which the cyanobacterial genus Chroococcidiopsis was found to be dominant. This could be attributed to the lack of sequence information about hypolith viruses/bacteria in public databases or the possibility that hypolithic communities incorporate viruses from the surrounding soil.
嗜光微生物群落是专门栖息在半透明岩石底面的沙漠特化群落。在这里，我们首次研究了从纳米布沙漠超干旱地区分离出来的这些群落中的病毒部分。对嗜光病毒群落的分类组成进行了调查，并对确定的序列进行了功能评估。系统发育分析表明，属于长尾病毒目，特别是肌尾病毒科的噬菌体最为普遍。功能分析并与其他宏病毒组进行比较表明，细胞壁降解酶、核苷酸还原酶 (RNR) 和噬菌体相关基因的频率相对较高。terL 和 phoH 标记基因的系统发育分析表明，许多序列是新颖的，与已知分离物不同，RNR 的分类分布表明这是一个新的环境。含有许多感染芽孢杆菌噬菌体的病毒嗜光部分的组成与纳米布嗜光细菌的系统发育调查不完全一致，其中蓝细菌属 Chroococcidiopsis 被发现占主导地位。这可能归因于公共数据库中缺乏关于嗜光病毒/细菌的序列信息，或者嗜光群落可能从周围土壤中引入病毒。
