**3.14 Single-cell protein**

The production of single-cell protein (SCP) can be done by microbial fermentation with selected strains of microorganisms. SCP also known as microbial protein or bio-protein [50]. Bacteria such as *Pseudomonas* spp. can be grown in methanol, ethanol and organic acids [3]. The protein and sulfur containing amino acids in bacteria are higher than that of yeast. The oil content in bacteria and yeast is high and rich in unsaturated fatty acids. Chen et al. [51] concluded that SCP produced by *Chlostridium autoethanogenum* had 88.93% crude protein and most of essential amino acids were higher than that of fish meal.

The incorporation of 15% of SCP in pigs diet exhibited a comparable results with those group of pigs fed diet containing soybean meal [3]. It is recommended that SCP can be included in 2–5% in broiler diets, and up to 10% in laying hens [3].
