The effect of mesquite extract on the nutritional qualities of single-cell protein

Abstract

Cells of Brevibaoterium JM98A were grown in a medium containing mesquite extract as the sole source of carbon. A 14 liter glass fermentor with automatic temperature and foam control was used for the study. Viable cell counts, protein production, and reducing sugar in both 1% and 0.5% mesquite extract were measured. The production of microbial protein was most efficient in both mesquite extracts during the first 24 hours of fermentation. The cell masses and total protein yields were greater with the 0.5% mesquite extract than 1.0% extract. The nutritional value of microbial cells grown on mesquite extract was determined by amino acid analysis and feeding trials. The lysine content of the microbial protein exceeded the FAO/WHO amino acid pattern and the requirements of infant and adult humans. The other essential amino acids, except methionine, met the FAO/WHO amino acid pattern and the requirements of humans at three stages of development. Net protein utilization (NPU) measurements indicated that the biological value of protein in the intact single cells was inferior to that of casein. There were no significant (P <0.01) differences in weight gain, nitrogen digestibility or NPU of experimental rats fed diets containing mesquite extract-grown cells and Trypticase Soy Broth-grown cells.