HYDROGEN - BIOLOGICAL CYCLE

The Hydrogen element is cycled by microbial organisms and using metalloenzymes. Although Hydrogen molecule (H₂) is present only to the extent of about it 0.5 parts per minutes( ppm) at Earth atmosphere, it's levels are 100 of times higher in anaerobic environments, such as wetland soils and sediments at the bottoms of hot springs and deep lakes.

              Hydrogen is produced in this O₂ free zones as the waste product of by fermentativ bacteria (strict anaerobes) which is break down into the organic compound and using H⁺ ions as an oxidant acting as a terminal electron acceptor. It's produced by the thermophilic organism that derive their carbon and energy entirely from carbon monoxide and by nitrogen fixing bacteria which yield H₂ as a byproduct of ammonia formation. Other microorganisms, many of the aerobic, use H₂ instead as a food and fuel are responsible for the formation of the familiar gases methane (CH₄) and H₂S as well as nitrite and other products.

                   In animals, the anaerobic environments of the large intestine is host to bacteria that from H₂ by the breakdown of carbohydrates. The mucus layer of the mouse intestine have been found to contain hydrogen molecule. The H₂ at levels above 0.04 mmol dm-³, equivalent to partial atmosphere of 5 % hydrogen molecule. In turn this hydrogen molecule is utilized by methane gas, such as found in ruminating mammals, to produce methane and by other bacteria, including dangerous pathogens such as the salmonella genus and Helicobacter pylori, which is responsible for gastric ulcers.

                          The high level of hydrogen molecule in the breath has been used to diagnose conditions related to carbohydrates - intolerance and these levels may reach at >70 ppm followed by the lactose ingestion by lactose - intolerance patients.

                    Industrial production of hydrogen molecule by microorganisms is a important area for research and development. There are two different types of approaches, each of which uses renewable energy. The first of these approaches is to use anaerobic organisms to ferment biomass from the sources ranging from cultivated biomass to domestic waste. The second involves of photosynthetic organisms such as a green cynobacteria and algae to produce hydrogen molecule as well as the biomass in either case hydrogen molecule can be extracted continuously by gas filters without the interruptions that would be required were harvesting required.