Immunochemistry of the Cell Walls of Methanogenic Archaea: A View from the Past into the Future

The study of cell walls has progressed considerably in recent years and has provided directions for future research that will soon result in practical applications. Accumulation of a variety of residues, which are toxic or at least space filling, along with threats of increased oil prices and the deleterious effects on the biosphere caused by the use of traditional fuels have stimulated the development of alternative resources of energy tied to technologies for waste elimination–reutilization and fuel production, using microbes, especially methanogenic archaea (in short, methanogens). Progress in the study of the microflora of man and animals has demonstrated the critical role of the resident microbes, including methanogens, in health and disease. These advances have boosted the study of methanogens in natural and manufactured ecosystems, including those in the gastrointestinal and urinary tracts, particularly concerning intermicrobial and microbial–host interactions that involve the cell wall. Consequently, the development of immunochemical methods for analysis, modification, manipulation, and use of methanogens in animal and human medicines and in industry has become a priority, promising significant results. The data in this Chapter on the immunochemical and molecular characteristics of the cell walls of methanogens, encompassing a range of evolutionary branches, will be useful to develop tools with direct applications in environmental, biotechnological, and medical research and practical endeavors. For example, the identification of distinct immunotypes in Methanobrevibacter smithii, which is by far the most frequent methanogen inhabiting the human body and plays a role in pathology by enhancing the pathogenesis of associated microbes, is the first step for determining which are the immunotypes most relevant for disease development. The same principle is valid for research directed toward the elucidation of which methanogenic immunotype is the most efficient for bioconversion of wastes with the highest yield of useful byproducts in waste-treatment plants.