Archaea mostly survives in the extremely severe environment and contains specific biological characteristics. According to the degree of temperatures for archaea that the NCBI provided, we divided the archaea into two classes: thermophiles and mesophiles. In this study, our objective is to extract some distinct characteristics from the archaea genomes that existed in the two classes as defined above. Thus, we could provide these characteristics to biologists for further research about the thermophilic or mesophilic archaea. Our approach included three steps: (1) constructing CDS groups, (2) searching for the unique groups, and (3) mining biological characteristics of unique groups. Firstly, we collect the protein amino-acid sequences (CDS) from the archaea genomes according to the degree of thermophilic of archaea, and then use BLAST to group the amino-acid sequences that provide the CDS with similar function in the same group. Secondly, we use the difference set property from set theory to find the distinct CDS group that exists in only one class, and verify the CDS groups as representative ones, if these groups appear in the majority of the members in that class. Finally, we mine the biological characteristics of these distinct groups from the well-known biological web site. We retrieve information of whole sequence of CDS of 50 archaea strains (29 strains are thermophilic , 21 mesophilic) from NCBI to establish a database of the CDS sequence (totally 100542 band ), we found 12 unique CDS groups that existed only in the anaerobic class.
