PROTEIN ISOLATES FROM CHLORELLA ALGAE, TORULA YEASTS, AND HYDROCARBON-ASSIMILATING MICROORGANISMS

• Published in: Journal of Nutritional Science and Vitaminology 1973, Vol.19(1), pp.1-13
• Main Author: MITSUDA, Hisateru
• Format: Article
• Language: English
• Subjects: Amino Acids, Essential - isolation & purification; Animal Feed; Carbon - analysis; Carotenoids - isolation & purification; Centrifugation; Chemical Phenomena; Chemical Precipitation; Chemistry, Physical; Chlorella - analysis; Chlorophyll - isolation & purification; Chromatography, Gel; Digestion; Fungal Proteins - isolation & purification; Hydrocarbons - metabolism; Methionine - analysis; Microscopy, Electron; Mitosporic Fungi - analysis; Mitosporic Fungi - metabolism; Nitrogen - analysis; Plant Proteins - isolation & purification; Proteins - isolation & purification; Solvents; Temperature
• ISSN: 0301-4800; 1881-7742
• DOI: 10.3177/jnsv.19.1

Preparation of protein isolates from the cells of Chlorella, Torula yeasts, and hydrocarbon-assimilating microorganisms is described. Simple pretreatment of the cells with alkali, acid, or some organic solvents enhanced the protein extraction efficiency and made the following purification procedures easier. Bleached cells of Chlorella obtained by growing the algae in a culture medium with high C/N ratio at high temperature were found to release protein more easily than do the normal cells. Structural changes in the cell wall region detected under the electron microscope may be responsible for this. The extracted protein was further purified. Amino acid composition of the protein isolates was determined, and their nutritional values were calculated. Among the essential amino acids the sulfur-containing amino acids were found to be the first limiting amino acid. Supplementing the isolate with methionine resulted in a significant increase in its nutritional value (PER) which became comparable to those of egg albumin and milk casein. The digestibility of the protein isolate from the cells of a hydro-carbon-assimilating yeast, tested in vitro with pepsin, was as high as 80% of that of the reference protein, milk casein, whereas that of the dried cells of the yeast was less than 50%. Viscosity was measured in regard to possible processed forms of the protein isolates. A few methods for disposing of the extraction residues were tested.