title: pH-control modes in a 5-L stirred-tank bioreactor for cell biomass and exopolysaccharide production by Tremella fuciformis spore.
abstract: The effect of pH-control modes on cell growth and exopolysaccharide production by Tremella fuciformis was evaluated in a 5-L bioreactor. The results show that the maximal dry cell weight (DCW) and exopolysaccharide production were 23.57 and 4.48 g L⁻¹ in pH-stat fermentation, where the maximal specific growth rate (μ(max)) and specific production rate of exopolysaccharide (P(P/X)) were 1.03 and 0.24 d⁻¹, respectively; under pH-shift cultivation, the maximal DCW and exopolysaccharide production were 30.57 and 3.90 g L⁻¹, where the μ(max) and P(P/X) were 1.21 and 0.06 d⁻¹. Unlike batch fermentation, maximal DCW and exopolysaccharide production merely reached 15.04 and 2.0 g L⁻¹, where the μ(max) and P(P/X) were 0.86 and 0.05 d⁻¹, respectively. These results suggest that a pH-stat strategy is a more efficient way of performing the fermentation process to increase exopolysaccharide production. Furthermore, this research has also proved that the three-stage pH-control mode is effective for cell growth.
authors.affiliation: State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Dongying 257061, PR China. zhuhu@upc.edu.cn
authors.forename: Hu
authors.initials: H
authors.lastname: Zhu
authors.forename: Chunxu
authors.initials: C
authors.lastname: Cao
authors.forename: Shuaishuai
authors.initials: S
authors.lastname: Zhang
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Weisheng
authors.initials: W
authors.lastname: Zou
mesh_terms: D001487:Basidiomycota / Q000378:metabolism*; D018533:Biomass; D019149:Bioreactors; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D011134:Polysaccharides / Q000096:biosynthesis*; D013172:Spores, Fungal / Q000378:metabolism*
chemical_list: D011134:Polysaccharides