NOVELTY - An anaerobic fermentation apparatus (A1) that involves use of population of substantially purified anaerobic bacterial strain for anaerobically fermenting a biomass into a chemical product comprises: sterilization and deoxygenation system; anaerobic digester containing bacterial population, equipped with anaerobic digester control system; pipelines and pumps for introducing and re-circulating biomass; and removal pipelines connected to digester for removing a chemical product from digester. The bacterial strain population is not subjected to a heatshocking process. INDEPENDENT CLAIMS are also included for: (1) process (P1) for anaerobic production of hydrogen involving: (a) obtaining a biomass material (M) as a nutrient for isolated non-heatshocked bacterial species from Clostridium; (b) concentrating the biomass material by at least a factor of 2 (preferably at least a factor of 4); (c) sterilizing the biomass; (d) deoxygenating the biomass material; and (e) fermenting the resultant biomass material with the isolated bacterial species under anaerobic conditions; (2) an apparatus (A2) for selecting bacteria for use in anaerobic hydrogen production comprising: a sealed chamber capable for providing an anaerobic environment and multiple growth conditions; (3) a program product for use in a computer that executes program instructions recorded in a computer-readable media to obtain candidate bacterial species for use in the anaerobic production of hydrogen from a biomass, comprising: a recordable medium; and several computer-readable program instructions on the recordable media that are executable by the computer to perform a method involving: (a1) determining a bacterial species of interest; (b1) determining the appropriate information for the bacterial species; (c1) repeating steps (a1) and (b1) for other bacterial species; and (d1) comparing appropriate information collected from step (c1) to assess optimal candidate bacterial species for use in the anaerobic production of hydrogen from a biomass; and (4) a bacterial culture (C1) comprising: a purified bacterial strain that produces hydrogen by anaerobically fermenting a biomass that has been deoxygenated without heatshocking the bacterial strain.    USE - As an anaerobic fermentation apparatus (A1) that involves use of population of substantially purified anaerobic bacterial strain for anaerobically fermenting a biomass into a chemical product; and for anaerobic production of hydrogen (claimed), which is useful as a clean, carbon dioxide neutral energy source for fuel cell vehicles and decentralized electricity generation in stationary fuel cell systems.    ADVANTAGE - The anaerobic digester apparatus and process provide the anaerobic digestion for production of hydrogen and other products by emulating a natural environment for anaerobic bacterial growth for achieving optimal hydrogen production; using different types of biomasses, as opposed to the prior art technologies that provide less efficient hydrogen production by anaerobic fermentation using genetically modified bacteria or by forcing the bacteria to exist in unnatural environments and coaxing them to produce hydrogen. The use of the non-engineered bacteria and several types of biomasses, results in production of hydrogen along with several other products including gasses and/or non-gaseous produces i.e. several solvents and organic acids.