Monitoring of pH and temperature effects in fermentation process of itaconic acid

Abstract

The environmental conditions such as temperature and pH have great impact on microbial growth kinetics and product formation during fermentation process. Temperature can be related to activation energy that affects the growth rates and death parameters while pH influences the activity of the enzyme and consequently affects the microbial growth rate and product formation. In this study, four different conditions were used to investigate the effects of temperature and pH on the formation of itaconic acid. The experiments were conducted using local strain Aspergillus terreus IMI 282743 in a 2.5 L laboratory fermenter (KF2.5L KoBiotech, Korean) for production of itaconic acid. The temperature and pH were changed for various fermentation conditions such as: (1) the temperature was controlled in the range of 30.0 +0.1oC and the pH was controlled in the range of 3.1-3.2, (2) the temperature was controlled in the range of 30.0 +0.1oC and the pH was increased to 7.0 before it was allowed to decrease in a natural way, (3) the temperature was allowed to change naturally but the pH was controlled in the range of 3.48-3.50, and finally, (4) both temperature and pH were allowed to change naturally throughout the fermentation cycle. From the four conditions above, the maximum itaconic acid production of 1.0 mg/mL was observed in the second state, in which the temperature was controlled in the range of 30.0 +0.1oC and the pH was initially increased to 7.0 before it was allowed to decrease naturally during the fermentation process.