초록
<P><B>Abstract</B></P> <P>Overproduction of metabolites, high product yield and process economics are greatly influenced by the media composition used for growth and fermentation. The main purpose of this study is to enhance the ethanol production through statistical tool of response surface methodology (RSM) by optimizing media components for the growth and fermentation of thermotolerant isolates <I>Kluyveromyces marxianus</I> NIRE-K1 and NIRE-K3. Five different salts were used in the Face-centered Central Composite Design (FCCD), with the responses of biomass formation and ethanol production for growth and fermentation, respectively. Yeast extract and K<SUB>2</SUB>HPO<SUB>4</SUB> were found to be the key media components for the growth and fermentation which is revealed from their interaction in both the yeast isolates. Further studies on batch fermentation kinetics using the optimized values of the medium composition for <I>K. marxianus</I> NIRE-K1 and NIRE-K3 resulted in final ethanol concentration of 17.73 (86.27% of theoretical ethanol yield) and 19.01 g l<SUP>−1</SUP> (94.12% of theoretical ethanol yield), respectively. An increase in the ethanol yield and productivity by 11.36, 10.42% and 2.0, 2.7% was revealed in NIRE-K1 and NIRE-K3, respectively, as compared to our previous study.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Statistical optimization of medium composition of novel thermotolerant ethanologens. </LI> <LI> Significant role of yeast extract and K<SUB>2</SUB>HPO<SUB>4</SUB> during growth of both isolates. </LI> <LI> Significant role of NaH<SUB>2</SUB>PO<SUB>4</SUB>, MgSO<SUB>4</SUB>, (NH<SUB>4</SUB>)<SUB>2</SUB>SO<SUB>4</SUB> during fermentation of both isolates. </LI> <LI> Improved ethanol yields by 11.36% and 10.42% by both isolates after optimization. </LI> <LI> Improved productivities by 2.00% and 2.70% by both isolates after optimization. </LI> </UL> </P>