Introduction: Single-cell protein biomass refers to dried cells of microorganisms such as bacteria, yeast, and mold, which can be used as a source of protein for livestock and poultry. This type of microorganisms grows on cheap and affordable carbon sources and during the fermentation process, producing single cell protein.Material and Methods: In this study, during the initial screening, methanol consumed microorganisms were isolated from the samples in the laboratory. In the second screening, these three microorganisms were compared for the selection of the best strain in terms of the specific growth rate, and the amount of production of biomass. Finally, the amount of crude protein in the biomass produced by the Bradford method was measured.Results: The results showed that bacterial number 2 (gram-positive coccobacillus) had the highest growth rate and maximum production of biomass among the three methanol consumed microorganisms. However, the isolated methylotrophic yeast was finally selected as a superior strain because these microorganisms (yeast) are rarely poisonous and pathogenic, and on the other hand, due to the reduction of nucleic acid content in yeasts than bacteria, the isolated yeast is at a higher level than the two bacteria in terms of safety. Finally, the amount of crude protein in the produced biomass was calculated to be 55%.
