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Growth and respiration of Petunia hybrida cells in chemostat cultures: A comparison of glucose‐limited and nitrate‐limited cultures
Author(s) -
de Gucht Luuk P. E.,
van der Plas Linus H. W.
Publication year - 2000
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/(sici)1097-0290(19961105)52:3<412::aid-bit7>3.0.co;2-n
Subject(s) - chemostat , respiration , petunia , nitrate , biology , botany , cellular respiration , biochemistry , ecology , bacteria , genetics , gene
Nitrate‐limited and glucose‐limited chemostat cultures of Petunia hybrida cells were compared at a specific biomass (+extracellular product) formation rate of 0.0042 C·mol/C·mol h. The composition of the biomass differed considerably in both culture types. The N/C (mol/mol) ratio in the biomass was almost four times lower in the nitrate‐limited than in the glucose‐limited cultures. On a dry weight basis (g/g DW) the biomass in the nitrate‐limited cultures contained about 2.5 times less ions and protein N and about 2.5 times more carbohydrates than the biomass in the glucose‐limited cultures. On a fresh weight basis (mmol/g FW) the biomass in nitrate‐limited and glucose‐limited cultures differed mainly in carbohydrate content. The yields of biomass on glucose and oxygen were generally higher in the nitrate‐limited than in the glucose‐limited cultures. Average values for these parameters were 0.27 C · mol biomass/C · mol glucose and 0.42 C · mol biomass/mol O 2 in the glucose‐limited cultures and 0.34 C · mol biomass/C · mol glucose and 0.55 C · mol biomass/mol O 2 in the nitrate‐limited cultures. On a C · mol basis the total respiration was about 25% and the maximally attainable cytochrome pathway activity (measured in the presence of hydroxamate) about 30% higher in the glucose‐limited than in the nitrate‐limited cultures. The maximally attainable activity of the alternative pathway (measured in the presence of KCN) was significantly lower in the glucose‐limited cultures. On an organic N (≈protein) basis all respiratory parameters were significantly higher in the nitrate‐limited cultures. In the presence of the respiratory uncoupler carbonyl cyanide p ‐trifluoromethoxy phenylhydrazone (FCCP) and excess glucose, cellular respiratory activity shows its maximal activity; under these conditions the total respiration increased more than 150% in the glucose‐limited and only 30% in the nitrate‐limited cultures. It is suggested that glucose‐limited cultures are able to react more flexibly to changes in the environmental conditions than nitrate‐limited cultures. © 1996 John Wiley & Sons, Inc.