BIOTECHNOLOGY - V. G. Herasymenko - 2006

Part II. Special Biotechnologies

Chapter 21. BIOTECHNOLOGY OF PROTEIN PRODUCTION

21.7. PRODUCTION OF MICROBIAL PROTEIN FROM PLANT WASTE HYDROLYSATES

Historically, one of the first substrates used to produce single-Cell microbial protein biomass was hydrolysates derived from plant waste, pre-hydrolysates, and sulfite liquor—by-products of the pulp and paper industry.

In the mid-1930s, The production of fodder Yeast using plant biomass hydrolysates was initiated in the former Soviet Union; however, this technology did not gain widespread adoption in the West. The core of this protein production process involves the acid Hydrolysis of plant Polysaccharides into pentoses and hexoses (via single-stage hydrolysis), or selectively into pentoses and hexoses separately (via two-stage hydrolysis). These sugars can either be utilized directly as a carbon and energy source for yeast cultivation, or converted into ethanol, which is subsequently transformed into yeast biomass.

The primary industrial producer strains are various yeast species—Candida utilis, C. scottii, and C. tropicalis—capable of assimilating both pentoses and hexoses, and even tolerating the presence of furfural in the growth medium.

The main advantage of this technology is obtaining a product free of raw material residues, thereby ensuring a more stable and controllable composition, as well as utilizing renewable raw material sources (plant biomass). The disadvantages include The Need for aggressive media and high pressures during the hydrolysis stage, significant operational costs for the process, and the logistics of transporting plant raw Materials. Hydrolysis plants typically operate on a smaller scale, though they historically made a major contribution to solving the shortage of feed protein. Fodder yeast produced from plant hydrolysates contains up to 43–58% protein.

In addition to plant-derived materials, hydrolysates of livestock waste (such as swine manure slurries) have also been utilized for cultivating fodder yeast, a technology previously implemented in Czechoslovakia.