Balch W E, Magrum L J, Fox G E, Wolfe R S, Woese C R
J Mol Evol. 1977 Aug 5;9(4):305-11. doi: 10.1007/BF01796092.
The 16S ribosomal RNAs from two species of methanogenic bacteria, the mesophile Methanobacterium ruminantium and the thermophile Methanobacterium thermoautotrophicum, have been characterized in terms of the oligonucleotides produced by digestion with T1 ribonuclease. These two organisms are found to be sufficiently related that they can be considered members of the same genus or family. However, they bear only slight resemblance to "typical" Procaryotic genera; such as Escherichia, Bacillus and Anacystis. The divergence of the methanogenic bacteria from other bacteria may be the most ancient phylogenetic event yet detected--antedating considerably the divergence of the blue green algal line for example, from the main bacterial line.
已根据用T1核糖核酸酶消化产生的寡核苷酸对两种产甲烷细菌（嗜温性的反刍甲烷杆菌和嗜热性的嗜热自养甲烷杆菌）的16S核糖体RNA进行了表征。发现这两种生物具有足够的相关性，可被视为同一属或科的成员。然而，它们与“典型的”原核生物属（如大肠杆菌、芽孢杆菌和集胞藻属）只有细微的相似之处。产甲烷细菌与其他细菌的分化可能是迄今检测到的最古老的系统发育事件——例如，比蓝藻系从主要细菌系的分化要早得多。
