Enhanced production of ethanol by high gravity glucose fermentation at temperatures above 40 oC by Saccharomyces cerevisiae S1 using a soya flour supplemented medium

Abstract

A locally isolated strain of Saccharomyces cerevisiae
S1 in peptone, yeast and mineral nutrient (PYN) medium
with 100 gL-1
of glucose showed optimum growth at 36 oC
and efficient ethanol production at 40 oC. To investigate the
effect of soya flour supplementation on ethanol fermentation,
PYN medium containing different concentrations of glucose
(50 to 400 gL-1
) with and without soya flour (26.8 gL-1
) were
used at 40 ºC for 48 h. The above experiment was repeated
at different temperatures (40, 43 and 45 ºC) for 48 h to find
the effect of soya flour supplementation on ethanol production
at higher temperatures and sugar levels. The highest ethanol
production efficiency (96.5 %) and the highest ethanol yield
(149.3 gL-1
) with efficient glucose utilization (100 %) was
observed in soya flour supplemented medium with a sugar
concentration of 300 gL-1
at 40 ºC. Further, it was observed
that at higher temperatures (43 and 45 ºC) and higher sugar
concentrations, soya flour supplemented media performed
well. With 300 gL-1
glucose at 43 and 45 oC the amounts of
ethanol produced in soya flour supplemented media was 80 and
30 gL-1
, respectively while in unsupplemented media it was
only 28 and 18 gL-1
, respectively. In glucose (400 gL-1
) – PYN
medium supplemented with soya flour, 78 (48 h) and 25 gL-1
(48 h) ethanol was produced at 43 and 45oC, respectively. The
study revealed that supplementation of media with soya flour
has not only improved the glucose fermenting capacity but
has also increased the efficiency of ethanol production and the
ethanol production rate at higher temperatures and high sugar
levels.