P149: Semi-pilot scale production of single cell protein by mixed culture of Candida utilis and Brevibacterium lactofermentum

This work aims to enrich beet pulp with lysine and other amino acids using individual pure cultures and mixed culture of Candida. utilis and Brevibacterium lactofermentum (BL) in a continuously stirred tank reactor (5 l) followed by large scale production in a 75-l (working volume 50 l) bioreactor. Best results were obtained with sequential fermentation carried out with BL added after 3 days to the C. utilis culture grown on beet pulp hydrolysate supplemented with molasses and glucose. BL mainly produced lysine (37.5 g/l) and glutamic acid, while mixed culture additionally produced leucine (4.13%), isoleucine (3.45%), phenyl alanine (1.65%), methionine (1.86 %), threonine (3.93%) and valine (2.81%). Semi-pilot scale study results showed that mixed culture of C. utilis and BL were found to maintain the achievements of each individual fermentation, yielding a high and stable production of crude protein, true protein, amino acids from optimized medium.  Crude protein increased from 11.3 to 54.5 %  and true protein from 0.0 to 32 % with mixed culture at semi-pilot scale. The amino acid profile of final microbial biomass protein obtained by mixed culture of C. utilis and BL in 75-l fermentor was enriched with all essential and non-essential amino acids. Mixed cultures in this study have shown a synergistic effect with possible industrial application.