title: Maximum-biomass concentration prediction for Bifidobacteria in the pH-controlled fed-batch culture.
abstract: Our objective was to systematically study the relationship between maximum biomass concentration of different Bifidobacteria and total-acid anions accumulation, and develop a prediction equation for the maximum biomass concentration in the fed-batch culture at pH-controlled 7·0. The accumulation of acid anions and the consumption of nutrients of various strains were evaluated. In addition, minimum inhibitory concentrations (MICs) of acid anions on a range of strains were examined at pH 7·0. The inhibition of acid anions, which had the same MIC as sodium chloride, was due to the osmotic pressure under pH 7·0 conditions. Moreover, the concentration of total-acid anions completely inhibiting each strain in the fed-batch culture at pH-controlled 7·0 had no significant differences with the MIC of acid anions for the corresponding strains. The osmotic pressures under two conditions were not significantly different. Finally, the maximum biomass concentration of Bifidobacteria was found to be closely related to biomass yield per unit of acid anion produced (YX/P ) and MIC (C) which were needed for the prediction, and different strains exhibited marked correlation (P ˂ 0·01, R = 0·985). An equation for the prediction of the maximum biomass concentration was developed as follows: Xmax -X0  = (0·71 ± 0·03)·YX/P ·C.
  
  
  CONCLUSIONS
  This study provides further insights into the inhibition of Bifidobacteria by dissociated acid anions (the dissociated form) at pH 7·0. The high correlation between different strains suggested that the equation established in this paper is appropriate for different strains of Bifidobacteria. The prediction equation could be used to guide practical production in the preparation of materials, the control of the end of fermentation and production plans for further products such as freeze-dried powder of Bifidobacteria or food fermentation.
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, China.
authors.forename: S M
authors.initials: SM
authors.lastname: Cui
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, China.
authors.forename: J X
authors.initials: JX
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, China.
authors.forename: X M
authors.initials: XM
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, China.
authors.forename: Y Q
authors.initials: YQ
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, China.
authors.forename: H
authors.initials: H
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, China.|Beijing Innovation Centre of Food Nutrition and Human Health, Beijing Technology & Business University, Beijing, China.
authors.forename: W
authors.initials: W
authors.lastname: Chen
mesh_terms: D000143:Acids / Q000494:pharmacology*; D000465:Algorithms; D061249:Batch Cell Culture Techniques; D001644:Bifidobacterium / Q000187:drug effects* / Q000254:growth & development*; D018533:Biomass; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D009997:Osmotic Pressure
chemical_list: D000143:Acids; D005947:Glucose
keywords: Bifidobacteria; acid anions; maximum biomass concentration; osmotic pressure; prediction equation