The cell from microorganisms such as bacteria, yeasts, filamentous algae treated in various ways and used as food, are called SCP (single cell protein).
SCP provides a protein rich supplement in human diet e.g. 250kg cow produces 200g of protein per day. In same time, 250g of microorganism like Methylophilus methylotrophus can produce 25 tonnes of protein because of it's high rate of biomass production and growth.