The initial pH is one of the important factors that affect
the performance of SSF. The effect of pH on ethanol
fermentation is studied by conducting batch experiments
at different pH ranging from pH 4.0 to 7.0 for yeast strains
namely S. cerevisiae MTCC- 170 by keeping initial substrate concentration (100 g/l), initial temperature (35°C),
inoculum age (17 h old culture) and agitator speed (120
rpm) for 24, 36 and 48 h of fermentation period. As
shown in Figure 2, the ethanol concentration was increased from pH 4.0 to 6.0 and then decreased marginally
above this value. The maximum ethanol concentration
7.70% was obtained from S. cerevisiae MTCC- 170 culture grown at pH 6.0. Fadel (2000) reported that high
ethanol production was obtained by using initial pH 5.0 to
6.0. It was also shown that no ethanol production exists
lower than pH 4.0 (Graves et al., 2006). Turhan et al.
(2008) reported that maximum ethanol yield, maximum
growth rate and biomass concentration were obtained at
pH 5.5 on carob as a medium for ethanol production.
Osman et al. (2011) tested wide initial pH range and
found that at pH 3.0 no growth was observed and no
ethanol was produced, while pH 6.0 was the optimum for
both biomass and ethanol production. Similar results
were obtained by Kadambini (2006). Mohanty et al.
(2009) reported that pH 6.0 was optimum for bioethanol
production from mahula (Madhuca latifolia L.) flowers by