title: Effect of propionic acid on citric acid fermentation in an integrated citric acid-methane fermentation process.
abstract: In this study, an integrated citric acid-methane fermentation process was established to solve the problem of wastewater treatment in citric acid production. Citric acid wastewater was treated through anaerobic digestion and then the anaerobic digestion effluent (ADE) was further treated and recycled for the next batch citric acid fermentation. This process could eliminate wastewater discharge and reduce water resource consumption. Propionic acid was found in the ADE and its concentration continually increased in recycling. Effect of propionic acid on citric acid fermentation was investigated, and results indicated that influence of propionic acid on citric acid fermentation was contributed to the undissociated form. Citric acid fermentation was inhibited when the concentration of propionic acid was above 2, 4, and 6 mM in initial pH 4.0, 4.5 and, 5.0, respectively. However, low concentration of propionic acid could promote isomaltase activity which converted more isomaltose to available sugar, thereby increasing citric acid production. High concentration of propionic acid could influence the vitality of cell and prolong the lag phase, causing large amount of glucose still remaining in medium at the end of fermentation and decreasing citric acid production.
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Xu
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.
authors.forename: Jia-Wei
authors.initials: JW
authors.lastname: Bao
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.
authors.forename: Xian-Feng
authors.initials: XF
authors.lastname: Su
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.
authors.forename: Hong-Jian
authors.initials: HJ
authors.lastname: Zhang
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Zeng
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Tang
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.
authors.forename: Ke
authors.initials: K
authors.lastname: Wang
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Zhang
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.
authors.forename: Xu-Sheng
authors.initials: XS
authors.lastname: Chen
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China. maozg@jiangnan.edu.cn.
authors.forename: Zhong-Gui
authors.initials: ZG
authors.lastname: Mao
mesh_terms: D019343:Citric Acid / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008697:Methane / Q000378:metabolism*; D011422:Propionates / Q000378:metabolism*; D062065:Wastewater / Q000382:microbiology*; D014871:Water Microbiology
chemical_list: D019343:Citric Acid; D008697:Methane; D011422:Propionates; D062065:Wastewater; C029658:propionic acid
keywords: Anaerobic digestion; Citric acid; Isomaltose; Propionic acid