A novel method for preparing high purity Actinobacillus succinogenes stock and its long-term acid production in a packed bed reactor

A. succinogenes is susceptible to contamination by other lactate producing bacteria. This reduces stability and makes long-term A. succinogenes fermentation difficult. In this study, the contaminated A. succinogenes culture, where the contaminant was shown to be ubiquitous Staphylococcus epidermidis, can be easily rescued by using xylose as the sole carbon source. The stability of purified A. succinogenes was verified in continuous fermentation using packed bed reactor while the performance of acid productions was investigated. While MgCO3 was used as a pH buffer and CO2 source during the continuous fermentation, the problem of MgCO3 clogging in a packed bed reactor was solved by oleyl alcohol reflux. This raised operation time from 344 to 1788 h. The provision of 30 g/L glucose and 40 g/L xylose as carbon sources resulted in a main metabolite yield of 91.7 ± 3.2% lactate and 55.3 ± 3.0% succinate with a stable productivity of 16.9 ± 1.7 and 1.5 ± 0.1 g·L−1·h−1.