The growth and fermentation kinetics of S. cerevisiae and Z.
mobilis cells were studied (Table 1). The ethanol concentration
(P) obtained with free cells of S. cerevisiae (24.83 g l1) was 21.2%
more than that of free cells of Z. mobilis (20.47 g l1), where as
the volumetric substrate uptake (Qs) was found to be 15.2% more
in case of S. cerevisiae (0.581 g l1h1) than that of Z. mobilis
(0.504 g l1h1). The ethanol yield (Yp/s = 0.445 g g1) and volumetric
product productivity (Qp = 0.258 g g1) obtained with S.
cerevisiae was found to be 5.2 and 21.1%, respectively higher than
that of Yp/s (0.423 g g1) and Qp (0.213 g g1) of Z. mobilis cells.
Likewise, the final sugar to ethanol conversion rate (%) with S. cerevisiae
cells was 5.27% more than that of Z. mobilis. However, the final
biomass concentration (X) of S. cerevisiae cells (4.34 g l1) was
134% higher than that of Z. mobilis cells (1.85 g l1), which might
be due to more tolerance to temperature and ethanol [17].
In this study S. cerevisiae (strain CTCRI) was found to be more
efficient than Z. mobilis MTCC 92 in ethanol production from mahula
flowers. Inuganti and Bhate [27] reported that mahula flower is
associated with several natural yeasts such as S. cerevisiae and S.
ellipsoideus. Hence, mahula flower considered as a suitable natural
habitat for S. cerevisiae which might have influenced its fermentation
capacity in comparison to Z. mobilis.