title: Efficient production of l-lactic acid from hydrolysate of Jerusalem artichoke with immobilized cells of Lactococcus lactis in fibrous bed bioreactors.
abstract: Hydrolysate of Jerusalem artichoke was applied for the production of l-lactic acid by immobilized Lactococcus lactis cells in a fibrous bed bioreactor system. Preliminary experiments had indicated that the high quality hydrolysate, which was derived from the 40 min acid treatment at 95 °C and pH 1.8, was sufficient to support the cell growth and synthesis of l-lactic acid. With the addition of 5 g/l yeast extract, the fermentative performance of free cell system was evidently improved. After the basal settlement of hydrolysate based fermentation, the batch mode and the fed-batch mode fermentation were carried out in the free cell system and the fibrous bed bioreactor system, respectively. In all cases the immobilized cells presented the superior ability to produce l-lactic acid. The comparison of batch mode and fed-batch mode also indicated that the growth-limiting feeding strategy could reduce the lag phase of fermentation process and enhance the production of l-lactic acid. The achieved maximum concentration of l-lactic acid was 142 g/l in the fed-batch mode. Subsequent repeated-batch fermentation of the fibrous bed bioreactor system had further exhibited the persistence and stability of this system for the high production of l-lactic acid in a long term. Our work suggested the great potential of the fibrous bed bioreactor system and hydrolysate of J. artichoke in the economical production of l-lactic acid at industrial scale.
authors.affiliation: The Key Laboratory of Biomass Chemical Engineering, Ministry of Education, Zhejiang University, Hangzhou 310027, China.
authors.forename: Zhouming
authors.initials: Z
authors.lastname: Shi
authors.forename: Peilian
authors.initials: P
authors.lastname: Wei
authors.forename: Xiangcheng
authors.initials: X
authors.lastname: Zhu
authors.forename: Jin
authors.initials: J
authors.lastname: Cai
authors.forename: Lei
authors.initials: L
authors.lastname: Huang
authors.forename: Zhinan
authors.initials: Z
authors.lastname: Xu
mesh_terms: D019149:Bioreactors / Q000382:microbiology; D001709:Biotechnology / Q000379:methods*; D018914:Cells, Immobilized / Q000378:metabolism*; D032561:Cotton Fiber; D005285:Fermentation; D006368:Helianthus / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D019344:Lactic Acid / Q000096:biosynthesis*; D013294:Lactococcus lactis / Q000378:metabolism*; D013696:Temperature
chemical_list: D019344:Lactic Acid