Non-wasteful fractionation of fragile yeast cells for the production of nutritional protein and other by-products

Abstract

 Saccharomyces cerevisiae 211 is a fragile yeast mutant whose cells grow only in media supplemented with osmotic stabilizer (1.6% NaCl), but which lyse spontaneously in water. This property provides a non-conventional way for isolation of nutritional protein and other products. We describe here a procedure based on the lysis ability of fragile yeasts for processing the biomass into several fractions. Cell lysis and downstream fractionation of the lysate do not include chemical or temperature treatment steps. The obtained protein fractions account for half of the starting biomass and contain 86% fully digestible protein and only 2% nucleic acids. The glycan fraction (with 83% polysaccharides) and the low molecular mass fraction are by-products of the procedure. The latter can be used as a nutritional media supplement in microbiology and as a source for purification of 5′-GMP, a potent flavour enhancer. The high rate of quantitative recovery and the mild conditions used to fractionate the biomass indicate the advantages of the fragile yeasts for production of nutritional protein and other products on a large scale by an efficient and non-wasteful technology.