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Propionate production optimization: influence of bacteria culture

Propionate production optimization: influence of bacteria culture
Typ:Bachelor Thesis
Datum:Immediately, by appointment

M. Sc. Rowayda Ali
Dr.-Ing. Florencia Saravia

Project Description (pdf)


Propionate is a valuable carboxylic acid produced through microbial fermentation. propionate is mainly used in food industry and other products such as cosmetic, plastics and pharmaceutical industries (Navone et al. 2018). Several microorganisms and different pathways can produce propionate during fermentation process. Propionibacterium is one of the organisms that play a critical role in propionate production process. These bacteria are commonly found in milk and dairy products. During the fermentation of milk, propionibacterium converts sugars and lactate in acetate, propionate, and carbon dioxide (Alfons J.M. Stams; Cor Dijkema 1998).

According to literature, propionic acid can be produced by lactic acid pathway during the fermentation of organic wastes using Propionibacterium (Li et al. 2016, Li et al. 2014, Luo et al. 2017). Moreover, preliminary work on hydrolysis of kitchen waste indicated that the lactate produced during the fermentation process was converted to propionate.  

In the framework of this bachelor thesis, the effect of adding microorganism found in dairy products (milk and cheese whey) to increase the propionate production process in the fermentation process will be assessed.


  • Research of relevant literature on the topic of investigation
  • Lab scale reactor experiments with different bacteria culture (AMPTs); AMPTs is a test using an anaerobic batch digestion process, which is commonly used to determine the biogas and methane yields from organic substrates.
  • Operation and Monitoring of the hydrolysis reactor including separation unit
  • Sampling of reactors and measure of organic acid concentration, DOC- and TS- concentrations, Gas composition, pH and el. conductivity
  • Evaluation of the influence of lactic acid producer bacteria on propionate production process