Propionic acid was produced from glycerol using Propionibacterium acidipropionici. In this study, the impact of the concentrations of carbon and nitrogen sources, and of different modes of high cell density fermentations on process kinetics and -efficiency was investigated. Three-way ANOVA analysis and batch cultivations at varying C/N ratios at pH 6.5 revealed that propionic acid production rate is significantly influenced by yeast extract concentration. Glycerol to yeast extract ratio (ww-1) of 3:1 was required for complete glycerol consumption, while maintaining the volumetric productivity. Using this optimum C/N ratio for propionic acid production in cyclic batch fermentation gave propionate yield up to 93mol% and productivity of 0.53gL-1h-1. Moreover, sequential batch fermentation with cell recycling resulted in production rates exceeding 1gL-1h-1 at initial glycerol up to 120gL-1, and a maximum of 1.63gL-1h-1 from 90gL-1 glycerol.
Bibliographical noteFunding Information:
The work was performed within the project BioVinn (Project no. 2008-00849) supported by the Swedish Governmental Agency for Innovation Systems (VINNOVA). Perstorp is acknowledged for coordination of the project. Swedish International Development Cooperation Agency (ASDI/SAREC) is acknowledged for supporting VHC during his stay at Lund University.
© 2014 Elsevier Ltd.
- Carbon:nitrogen ratio
- Cyclic batch fermentation
- Propionibacterium acidipropionici
- Propionic acid
- Sequential batch fermentation