Methanogenic Archaea
Methanogenic Archaea are ancient microorganisms that generate methane as a waste product of their normal cellular activities. This metabolism of environmental compounds by microorganisms involves generation of enzymes and enzymatic control mechanisms that can systematically break (and make) chemical bonds to extract energy and convert these materials into other carbon compounds and water.

The controlled expression of gene products involved in methanogenesis is essential for complete biomass conversion to generate alcohol fuels or for removal of waste products, and for bioremediation in marine sediments where oxygen is not present. Since Archaea were recently discovered, they have yet to be fully characterized.

Bioremediation of PCBs
Researchers have found that as few as two or three strains of bacteria can work together to break down commercial mixtures of polychlorinated biphenyls (PCBs), a family of highly toxic compounds that are widespread contaminants of the nation's waterways. Now these researchers have also been able to grow these useful strains of bacteria in the laboratory, paving the way for bioremediation strategies based on naturally-occurring microorganisms.

Polychlorinated biphenyls (PCBs) were widely used between 1929 and the late 1970s for industrial applications requiring chemical stability, low flammability, and high vaporization temperature. The stable properties of these compounds led to their widespread accumulation in the environment, first documented in the 1960s, and to growing concerns about the effects of these environmental contaminants on the health of humans and wildlife.

One of the difficulties with microbiological degradation in the environment is that commercial mixtures of PCBs, known as Aroclors, can contain over 100 different chemical forms. Until now, it was widely assumed that many types of microorganisms would be required to break them down. The requirement for only two or three strains in the laboratory that can do the job opens to the door to development of a large-scale bioremediation strategy.

The ability to now culture these microorganisms in the laboratory combined with development of sensitive methods for their detection will enable researchers to study how PCBs are degraded in the environment and design approaches for treating PCB contaminated sites that avoid the inherent limitations and expense of dredging.