초록
<P><B>Abstract</B></P> <P>The development of a low cost medium for ethanol production is critical for process feasibility. Ten media were formulated for <I>Clostridium ragsdalei</I> by reduction, elimination and replacement of expensive nutrients. Cost analysis and effects of medium components on growth and product formation were investigated. Fermentations were performed in 250mL bottles using syngas (20% CO, 15% CO<SUB>2</SUB>, 5% H<SUB>2</SUB> and 60% N<SUB>2</SUB>). The standard medium M1 cost is $9.83/L, of which 93% is attributed to morpholinoethane sulfonic acid (MES) buffer. Statistical analysis of the results showed that MES removal did not affect cell growth and ethanol production (<I>P</I> >0.05). Based on cells’ elemental composition, a minimal mineral concentration medium M7 was formulated, which provided 29% higher ethanol yield from CO at 3% of the cost compared to medium M1. Ethanol yield from CO in the completely defined medium M9 was 36% higher than while at 5% the cost of medium M1.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Design of a low cost medium for ethanol production is key for process feasibility. </LI> <LI> We formulated and compared ten syngas fermentation media for <I>Clostridium ragsdalei.</I> </LI> <LI> Nutrient effects on growth and production during syngas fermentation were examined. </LI> <LI> Ethanol yield from CO for defined medium M9 was 36% higher than standard medium M1. </LI> <LI> Cost of completely defined medium M9 was 5% of the cost of standard medium M1. </LI> </UL> </P>