Apart from the basic input, the right course of fermentation process is determined by the appropriate microorganism populations and the parameters such as: pH, particle size, ionic strength (salinity) and concentration of nutrients and toxic compounds. Three microorganism groups are involved in the process of anaerobic transformation of organic substances in fermentation gas: acid forming bacteria, acetate bacteria and methanogenic bacteria. The first two phases are dominated by the bacteria which are both obligate, facultative and absolute anaerobes (Clostridium spp., Bifidobacterium spp., Streptococcus spp., Enterobacter spp., Bacillus spp., Pseudomonas spp., Aerobacter spp., Alcaligenes spp, Escherichia spp, Lacto¬bacillus spp, Micrococcus spp. czy Flavobacterium spp.) [Nimmrichter, Kuebler, 1999]. Their number during the mesophile fermentation is estimated for between 108-109 per 1ml [Hartman, 1999]. The rate of bacteria growth at both phases fluctuates from 5 hrs, in the presence of carbohydrates to 72 hrs during fat decomposition [Heidrich, Nieścier, 1999]. Presented research aimed at determining the quantity and quality of biogas depending on the microbiological environment in fractions originating from agriculture and agro-food industry. To achieve the objective of research, was evaluated the number and biodiversity of microorganisms that inhabit selected agricultural raw materials used in the production of biogas. A very important ...
