초록
<P><B>Abstract</B></P> <P>A thermotolerant, mixed culture with <I>Bacillus coagulans</I> as a dominating bacterium was grown for production of lactic acid. Acid extraction using Amberlite™ IRA-67 weak base resin in a recirculation loop with a fermentation vessel was implemented to maximize culture productivity by maintaining a concentration of lactic acid below 20g/L. Productivity of this fermentation was found to be 1.3-fold higher than a control fed-batch process. Characterization of the resin through isotherm analysis produced data that fit well (<I>R</I> <SUP>2</SUP> >0.99) to both Langmuir and Redlich–Petersen models with a Langmuir monolayer loading of 203.8mgacid/g resin. Resin stability was tested over 108 days of fermentation on corn stover hydrolysate. During this fermentation, resin capacities for lactic and acetic acid were on average 112.2mg/g and 19.6mg/g, respectively, with no statistical evidence for change lactic acid capacity after reuse. However, acetic acid capacity on average dropped 4.9% per reuse.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>Bacillus</I> culture used for non-sterile lactic acid fermentation of biomass sugars. </LI> <LI> Extractive fermentation of lactic acid with ion exchange resin was conducted. </LI> <LI> 1.33-Fold increase in productivity observed over traditional fed batch fermentation. </LI> <LI> Fermentation pH was controlled using ion exchange resin to extract product. </LI> <LI> Resin capacity for acid was stable over 100 days of fermentation on corn stover. </LI> </UL> </P>