Abstract
A mathematical model was developed to describe batch and continuous fermentation of glucose to organic acids with Clostridium tyrobutyricum. A modified Monod equation was used to describe cell growth, and a Luedeking-Piret equation was used to describe the production of butyric and acetic acids. Using the batch fermentation equations, models predicting butyric acid selectivity for continuous fermentation were also developed. The model showed that butyric acid production was a strong function of cell mass, while acetic acid production was a function of cell growth rate. Further, it was found that at high acetic acid concentrations, acetic acid was metabolized to butyric acid and that this conversion could be modeled. In batch fermentation, high butyric acid selectivity occurred at high initial cell or glucose concentrations. In continuous fermentation, decreased dilution rate improved selectivity; at a dilution rate of 0.028 h−1, the selectivity reached 95.8%. The model and experimental data showed that at total cell recycle, the butyric acid selectivity could reach 97.3%. This model could be used to optimize butyric acid production using C. tyrobutyricum in a continuous fermentation scheme. This is the first study that mathematically describes batch, steady state, and dynamic behavior of C. tyrobutyricum for butyric acid production.
Highlights
Organic acids can be produced from biomass-derived sugars through fermentation
Pure butyric acid is used in food flavors, and esters of butyric acid are widely used as additives in the perfume industry [1,2]
The initial glucose concentration was varied by feeding medium with different glucose concentrations, and the initial cell mass was varied by purging different volumes of fermentation broth
Summary
Organic acids can be produced from biomass-derived sugars through fermentation. One of these products, butyric acid, has many applications in the food and perfume industries. Butyric acid is used to produce the biodegradable polymer β-hydroxybutyrate and in the production of several drugs [3]. Butyric acid might find application as an intermediate in the production of one of the generation of biofuels, biobutanol, through two-step fermentation as described by Ramey [4]. Butyric acid is currently produced chemically, which starts from the oxosynthesis of propylene [5]. The fermentation process to produce butyric acid is difficult because it forms multiple products at low concentrations, which greatly increases downstream separation costs
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
