Blackall L L, Rossetti S, Christensson C, Cunningham M, Hartman P, Hugenholtz P, Tandoi V
Department of Microbiology, University of Queensland, Brisbane, Australia.
Lett Appl Microbiol. 1997 Jul;25(1):63-9. doi: 10.1046/j.1472-765x.1997.00176.x.
The name Tetracoccus cechii is proposed for two strains of the tetrad arranged cocci, previously known as 'G' bacteria, which were isolated from laboratory scale activated sludge plants in the Czech Republic and in Italy. They were morphologically, phenotypically and phylogenetically characterized and found to comprise a novel lineage in the alpha-3 group of the proteobacterial phylum in the domain Bacteria. The strains are Gram-negative and produce intracellular inclusions of poly-beta-hydroxybutyrate. Although commonly seen in activated sludge mixed liquor as cocci 1-2 microns in diameter, arranged in tetrads, in pure culture they can also grow in amorphous aggregations and the cells are generally more variable in their size and shape with coccobacilli as well as cocci being present. They are not able to grow phototrophically, nor can they reduce nitrate beyond nitrite nor grow anaerobically. The closest phylogenetic neighbours of T. cechii are Rhodobacter sphaeroides and R. capsulatus which are 93% similar by 16S rDNA comparison. Tetracoccus cechii is oxidase- and catalase-positive, non-motile and has an optimal growth temperature between 25 degrees and 35 degrees C. The 16S rRNA of T. cechii has a 21 nucleotide deletion in the V9 region (Escherichia coli positions 1258-1278) and this feature is a unique molecular synapomorphy in the alpha-3 group.
为从捷克共和国和意大利的实验室规模活性污泥处理厂分离出的两株呈四联排列的球菌（以前称为“G”细菌）提议命名为切氏四联球菌。对它们进行了形态学、表型和系统发育特征分析，发现它们在细菌域变形菌门的α-3组中构成一个新的谱系。这些菌株为革兰氏阴性菌，能产生聚-β-羟基丁酸的细胞内包涵体。虽然在活性污泥混合液中通常可见直径为1-2微米的球菌呈四联排列，但在纯培养中它们也能以无定形聚集体生长，并且细胞大小和形状通常更具变异性，存在球菌和球杆菌。它们不能进行光合生长，也不能将硝酸盐还原至亚硝酸盐以下，也不能厌氧生长。切氏四联球菌最接近的系统发育邻居是球形红杆菌和荚膜红杆菌，通过16S rDNA比较相似度为93%。切氏四联球菌氧化酶和过氧化氢酶呈阳性，无运动性，最佳生长温度在25摄氏度至35摄氏度之间。切氏四联球菌的16S rRNA在V9区域（大肠杆菌位置1258-1278）有一个21个核苷酸的缺失，这一特征是α-3组中独特的分子共衍征。
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