Abstract: A production method of a biogas of the present invention comprises carrying out hydrogen fermentation of a subject solution containing organic matter with the use of a hydrogen fermentation microorganism, in which according to a correlation between a concentration of a predetermined substrate in a liquid to be processed containing an organic matter and a rate of consumption of the substrate by a hydrogen-fermenting microorganism a maximum tolerable concentration of the substrate consumable by the hydrogen-fermenting microorganism is determined in advance and in which in the actual hydrogen formation step, the concentration of the substrate in the liquid is maintained at one not higher than the maximum tolerable concentration. According to the production method of a biogas of the present invention, hydrogen fermentation can be performed sufficiently smoothly without any treatment of the material involving consumption of thermal energy such as heating/warming.

Abstract: A production method of a biogas of the present invention comprises carrying out hydrogen fermentation of a subject solution containing organic matter with the use of a hydrogen fermentation microorganism, in which according to a correlation between a concentration of a predetermined substrate in a liquid to be processed containing an organic matter and a rate of consumption of the substrate by a hydrogen-fermenting microorganism a maximum tolerable concentration of the substrate consumable by the hydrogen-fermenting microorganism is determined in advance and in which in the actual hydrogen formation step, the concentration of the substrate in the liquid is maintained at one not higher than the maximum tolerable concentration. According to the production method of a biogas of the present invention, hydrogen fermentation can be performed sufficiently smoothly without any treatment of the material involving consumption of thermal energy such as heating/warming.

Abstract: A bacterium capable of producing ethanol at a temperature of 40° C. or more from a carbon compound which is gaseous at ordinary temperature and ordinary pressure as the raw material, and a process for producing ethanol by culturing the bacterium at 40° C. or more.

Abstract: This invention provides a new fermentation method and apparatus for the same for producing a substance by a microbial action from a gaseous substrate, wherein the cells of a microorganism fixed to a carrier are held in a reactor, an aqueous solution is fed to said reactor so as to moisten at least part of the surface of said microbial cells, and said gaseous substrate is forced to pass through the interstices of said microbial cells, thereby causing direct reaction between the microorganism and the gaseous substrate and effecting efficient biosynthesis of methane, formic acid and other substances.