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Observations of aerobic, growing escherichia coli metabolism using an on‐line nuclear magnetic resonance spectroscopy system
Author(s) -
Chen Ruizhen,
Bailey James E.
Publication year - 1993
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/bit.260420209
Subject(s) - anaerobic exercise , bioreactor , chemistry , nuclear magnetic resonance spectroscopy , extracellular , intracellular ph , escherichia coli , intracellular , analytical chemistry (journal) , chromatography , nuclear magnetic resonance , biophysics , biochemistry , biology , physiology , physics , organic chemistry , gene
An experimental system has been constructed which enables on‐line measurements of phosphorus‐31 ( 31 P) nuclear magnetic resonance (NMR) spectra for growing bacterial suspensions under anaerobic or aerobic conditions. A sample stream from a laboratory bioreactor is circulated to the NMR sample chamber in a gas exchange system which permits maintenance of aerobic conditions for high‐cell‐density cultures. 31 P NMR spectra with resolution comparable with those obtained traditionally using dense, concentrated, nongrowing cell suspensions can be obtained at cell densities above 25 g/L with acquisition times ranging from 14 to 3 minutes which decline as cell density increases. This system has been employed to characterize the changes in intracellular state of a stationary phase culture which is subjected to a transition from aerobic to anaerobic conditions. Both intracellular NTP level and cytoplasmic pH are substantially lower under anaerobic conditions. Also, the system has been employed to observe the response of a growing culture to external addition of acetate. Cells are able to maintain pH difference across the cytoplasmic membrane at extracellular acetate concentrations of 5 and 10 g/L. However, acetate concentrations of 20 g/L cause collapse of the transmembrane ΔpH and sharp reduction of the growth rate of the culture. The experimental configuration described should also permit NMR observations of many other types of microbial cultures and of other nuclei. © 1993 John Wiley & Sons, Inc.