The natural biological community not disturbed by human is the only means to maintain the local and global environment adaptable for living activities.The stability of the global climate is just based on the adjusting function of the natural biological community which is determined by genome of the composite species.Developing and transforming the community by man may lead to the chromosome distortion and gene deficiency.Once the disturbance toward the community ceases,the biological community will restore the environment to a state adaptable for its existence.
Use of 16S-23S intergenic transcribed spacer (ITS) variability,as a relatively new method,is becoming an important supplement to the molecular methods based on 16S rRNA for which has a fairly constant size and is not divergent enough to give good separation in close relationships. This paper summarizes the structures and characteristics of ITS regions that are extremely variable in copy number,length and sequence per genome. The ITS region can be amplified easily taking advantage of conserved nucleotide stretches at the 5’ of the 16S and 3’ of the 23S gene,and the amplicon can contain different amounts of the 16S rDNA by choosing primers at different conserved areas within this gene. These primers are listed and discussed for perfecting the methodology of ITS. Furthermore,some recent progresses on the taxonomy,identification and community analysis of bacteria by means of ITS in epidemiology,ecology and artificial environment are reviewed,as well,the virtues and limitations of that method are discussed. Fig 2,Tab 1,Ref
