A fermentation process for producing both ethanol and lysine‐enriched yeast

Abstract

In 18 batch-fermentation experiments, baker's yeast was grown in an enriched mineral medium, containing 10% by weight glucose, at various pH and temperature levels. The pH and temperature are just two representative engineering variables which can be easily varied at negligible cost. The commercial yeast inoculum, 20% by weight or about .16% viable cells, was selected to represent industrial (nonsterile) conditions. Free L-lysine, ethanol, and cell growth were followed in time for each batch run held at a fixed pH and temperature. The maximum free lysine level reached at either 10 1/2 or 24 hr occurred at a pH of 5 and 32 degrees C. At 24 hr, the peak free lysine level, 120 mg/liter, is three times as great as the uncontrolled pH counterpart. In terms of total L-lysine (free plus protein-bound) the peak represents a 25% improvement over the uncontrolled case, based on an average 3.5% lysine level per cell weight. The greatest measured cell level, .9% by weight in the fermentation broth, or a 5 1/2-fold increase over th inoculum, was reached during the 36 degrees C and pH 3 run, while the largest measured ethanol value (3%, or 30% conversion by weight from glucose) was achieved during the 28 degrees C and pH 6 experiment. The optimal lysine run product, however, no less than 15% of the maximum cell and 30% of the maximum ethanol levels.

Kudzu (Pueraria lobata) root starch as a substrate for the lysine-enriched baker's yeast and ethanol fermentation process

“…paper (Tanner et al, 1977). Because of its direct relevance to this work it is worth recapitulating the synthetic medium used as a basis in this study.…”

“…The aeration was held constant at (1.4 vol of air) min'1 (fermentor liquid volume)'1. All other conditions and equipment employed are those previously described (Tanner et al, 1977).…”

“…In a previous paper (Tanner et al, 1977), a fermentation process was proposed for producing lysine-enriched baker's yeast to help alleviate human protein malnutrition, and ethanol, for use as a liquid fuel such as a gasoline entender. In that earlier paper, glucose was used as a model substrate.…”

Multiple Steady States in Continuous Fermentation Processes with Bimodal Growth Kinetics

“…The bimodal function µ(8), shown in Figure 9, was suggested from bátch culture data of S. cerevisiae grown on glucose limiting media at 32 °C and pH 5 (Tanner et al, 1977). Since the chemostat system is described in terms of two variables, (S) and (X), it is convenient to use a phase plane to describe its transient response.…”

Πειραματικη Και Τεχνοοικονομικη Αξιολογηση Συστηματων Που Αξιοποιουν Ενεργειακακυτταρινουχα Υλικα Προς Αιθανολη. Συνθεση Και Αριστοποιηση Ενος Βιωσιμου Τεχνολογικου Συστηματος

“…Επίσης ορισμένα απο τα υλικά αυτά μπορούν να χρησιμοποιηθούν για την παράγωγη ζωοτροφών [Tanner et al, 1977], ως συμπληρωματικές πήγες ενέργειας ή για την παράγωγη αιθανολης (πεντοζες) με τη βοήθεια άλλων μικροβιακών συστημάτων, π.χ. Pachysolen tannophilus [Schvester et al, 1983].…”