the bacteria are divided into two main groups or subkingdoms : the archaea, or archadbacteria, which often occur in extreme conditions, such as hot springs; and the eubacteria, which include the vast majority of bacteria 细菌可以再继续划分为两个亚界,一个亚界是古细菌亚界,这个亚界中的很多细菌可以在一些极端环境下生存,例如高温温泉等。