Single cell protein (SCP) production and potential substrates: A comprehensive review

Abstract

Single cell proteins (SCP) are the edible dead, dry cells of microorganisms that can be used as protein source in human food and animal feed, either as whole living cell or in dried form. Microbial species of yeast, fungi and bacteria that are Generally Recognized As Safe (GRAS), can be used as a source of single cell protein. Inexpensive microbial growth culture components can be utilized as source of carbon and energy to grow these microorganisms as biomass, amino acids or protein source. Besides being used as food or feed supplement, single cell protein strains have diverse range of properties, as it can eradicate pathogenic microorganism from human or animal gut either by competition with available nutrient sources or by producing enzymes or metabolites with antimicrobial activities. Due to increase in population around the globe, the global demand for high-quality protein rich foods have increased. Novel approaches for alternative sources are needed to meet the global challenges. SCP strains with capacity to produce cell wall degrading enzymes and metabolites with antimicrobial activity can play a major role to meet the global food demand. Poultry farming of broiler and layer is already playing an important role to meet the need of protein in the developing world. However, high nucleic acid content, un-digestible cell wall, unacceptable flavors and colors and high contamination rate are the certain limitations that need further attention.

Single Cell Protein: A Potential Substitute in Human and Animal Nutrition

“…There are different kinds of substrates, as categorized in [14]: The choice of substrate is made according to cost, availability, oxygen required during fermentation, quantity of heat produced and cooling capacity of the fermenter, but also the cost related to post-treatment processing [8,14]. Selected substrates are used as a growth medium by microorganisms such as bacteria, algae, fungi and yeast for increasing their cell mass, which is made up of SCP [15].…”

“…A variety of substrates and microbes have been used for SCP production; however, presence of toxic and carcinogenic compounds (aflatoxins of type B1, B2, G1 and G2, citrinin, trichothecenes and zearalenone) generated during the production process should always be considered. The two main limiting factors for yeast are the high nucleic acid content and low cell-wall digestibility [14,71,111]. A series of studies conducted worldwide show promising results concerning the possibility of using yeast as SCP, as reflected in Table 4.…”

Biotechnological Production of Sustainable Microbial Proteins from Agro-Industrial Residues and By-Products

“…The selection of the appropriate production microorganism is of great importance in every biotechnological process. Precisely because of this, microorganisms for SCP production are chosen based on oxygen requirements and heat generation during fermentation, foam character, growth rate, productivity, and/or yield of specific low-cost substrates, tolerance to temperature and pH, genetic stability, growth morphology, end product composition and structure, having regard to ease of protein recovery and purification [36,37]. Although several examples of SCP production by heterotrophic bacteria are given in the scientific literature, most heterotrophic SCP produced on an industrial scale has been synthesized with yeast or fungi [14].…”

Most promising alternative protein sources possible to use in sports nutrition – A review

“…Another problem is the relatively high production costs, which will begin to fall over time, but there are now cheaper alternatives for obtaining the protein. One factor that raises the price of SCP production is the breakdown of nucleic acids, in which these products are very abundant (6–10%) (Raziq et al., 2020). Unfortunately, humans should not consume large amounts of nucleic acids because of the potential for uric acid deposition in the body, which is caused by the breakdown of purines that make up single‐cell RNA.…”