ABSTRACT
This chapter points out an efficient genetic transformation system, vector systems for genetic recombination, and the selection of genetic markers that can be constructed for methanogenic bacteria which at least for certain standard strains. It focuses on the recent progress in establishment of recombinant DNA technology in methanogens. The chapter summarizes the applied microbiological investigations on methane fermentation. Although some methanogenic bacteria are extreme thermophiles or halophiles, for biochemical and genetic research on methanogens, several standard strains are diversely unrelated in terms of their microbiological characteristics. Genetically marked strains are a prerequisite for genetic studies; these strains could be employed to develop a genetic-exchange system in methanogens based on an efficient selection system. Expression of the archaeal genomes in well-studied prokaryotic or eukaryotic microorganism has been examined by molecular-cloning techniques, even without host-vector system in methanogens.
