title: Effect of acetic acid on citric acid fermentation in an integrated citric acid-methane fermentation process.
abstract: An integrated citric acid-methane fermentation process was proposed to solve the problem of extraction wastewater in citric acid fermentation process. Extraction wastewater was treated by anaerobic digestion and then recycled for the next batch of citric acid fermentation to eliminate wastewater discharge and reduce water resource consumption. Acetic acid as an intermediate product of methane fermentation was present in anaerobic digestion effluent. In this study, the effect of acetic acid on citric acid fermentation was investigated and results showed that lower concentration of acetic acid could promote Aspergillus niger growth and citric acid production. 5-Cyano-2,3-ditolyl tetrazolium chloride (CTC) staining was used to quantify the activity of A. niger cells, and the results suggested that when acetic acid concentration was above 8 mM at initial pH 4.5, the morphology of A. niger became uneven and the part of the cells' activity was significantly reduced, thereby resulting in deceasing of citric acid production. Effects of acetic acid on citric acid fermentation, as influenced by initial pH and cell number in inocula, were also examined. The result indicated that inhibition by acetic acid increased as initial pH declined and was rarely influenced by cell number in inocula.
authors: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.
authors: Jian
authors: J
authors: Xu
authors: Yang-Qiu
authors: YQ
authors: Chen
authors: Hong-Jian
authors: HJ
authors: Zhang
authors: Lei
authors: L
authors: Tang
authors: Ke
authors: K
authors: Wang
authors: Jian-Hua
authors: JH
authors: Zhang
authors: Xu-Sheng
authors: XS
authors: Chen
authors: Zhong-Gui
authors: ZG
authors: Mao
mesh_terms: D019342:Acetic Acid / Q000378:metabolism / Q000494:pharmacology; D001234:Aspergillus niger / Q000254:growth & development*; D019343:Citric Acid / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents / Q000378:metabolism / Q000494:pharmacology; D008697:Methane / Q000378:metabolism*; D062065:Wastewater / Q000382:microbiology; D018508:Water Purification
chemical_list: D019342:Acetic Acid; D019343:Citric Acid; D007202:Indicators and Reagents; D008697:Methane; D062065:Wastewater