Urea-Appended Amino Acid To Vitalize Yeast Growth, Enhance Fermentation, and Promote Ethanol Production

The development of sustainable protocols
for enhancing the production
of ethanol is highly important for its utilization in automotive transportation
and energy sector. Up to 15% ethanol can blend with diesel to make
e-diesel that can be used in fuel compression ignition engine. Urea-modified
amino acids can be used as a very good vitalizer for yeast (Saccharomyces cerevisiae, Baker’s yeast (ATCC
204508)) growth and thus promote ethanol production. A simple, one-step,
room-temperature synthetic procedure has been developed for urea-appended
α-amino acids from amino acid by treatment with KCNO. Single-crystal
X-ray studies confirm the successful synthesis and molecular structures
of the urea-appended α-amino acids. Out of 20 urea-appended
amino acids, Arg-, Pro-, His-, and Gln-containing compounds promote
yeast growth significantly after 12 h at pH 6.8 and 38 °C. These
compounds are nontoxic. The urea-appended Arg shows 2-fold increase
of yeast growth. However, urea-appended m-aminobenzoic
acid and p-aminobenzoic acid inhibit yeast growth.
NMR experiments confirmed the enhanced production of ethanol by glucose
fermentation in the presence of 2.5 μmol urea-appended Arg.
Not only glucose but also commercially available sugars and feedstock
of the starch slurry drained out after boiling of rice exhibit significant
enhancement of ethanol production under same conditions.