极端嗜酸热古菌S5菌株的重新分类研究

对已经鉴定的嗜酸热硫球菌 (Sulfosphaerellusthermoacidophilumgen.nov .sp .nov)S5菌株的进一步研究发现 ,它既能在好氧条件也能在厌氧条件下代谢元素硫进行化能自养生长 ,结合其 1 6SrRNA基因的分子系统学分析 ,S5菌株应归于Acidianus属。另外 ,S5菌株与Acidianus属中三个已知种基因组DNA的同源性分别仅有 44%、2 2 %和 2 3% ,DNA中G +Cmol%为 38,与已知种 31 0和 32 7有较大差异 ;而且 ,在代谢特性上S5菌株为专性化能无机营养型 ,与Acidianusbrierleyi有明显不同。因此S5菌株应是Acidianus属中一个新种 ,建议定名为 :腾冲嗜酸两面菌 (Acidianustengchongensessp .nov .)。

STUDY ON RECLASSIFICATION OF EXTREMELY THERMOACIDOPHILIC ARCHAEA STRAIN S5

The further study on thermoacidophilic archaea strain S5, with has been identified as Sulfosphaerellus thermoacidophilum gen.nov.,sp.nov, has shown it was able to grow facultatively aerobically by means of two sulfur-metabolizing modes of chemolithotrophy which is the characteristic of Acidianus. And the 16SrRNA gene of strain S5 was amplified, cloned and sequenced, a phylogenetic tree was constructed on the 16SrRNA gene sequences. The tree clearly indicated that strain S5 formed the same lineage with Acidianus brierleyi. Thus strain S5 should be the member of Acidianus. However, there are only 44%, 22% and 23% genomic DNA similarity between S5 and A. brierleyi. A. infernus and A. ambivalens, respectively. And the G + C content of S5 DNA is 38%, which is 5% ~ 7% higher than the reported G + C contents of the other Acidianus species (31% or 32.7%) . In addition, strain S5 is a strictly chemolithoautotrophs, which is obviously different from facultative chemolithotrophs of A brierleyi. Based on the observed differences, strain S5 represents a new species within the genus Acidianus. A new species name, Acidianus tengchongenses, was proposed for it. The type strain is designated S5.