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Molecular and phase toxicity of compressed and supercritical fluids in biphasic continuous cultures of Clostridium thermocellum
Author(s) -
Bothun Geoffrey D.,
Knutson Barbara L.,
Strobel Herbert J.,
Nokes Sue E.
Publication year - 2004
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.20309
Subject(s) - supercritical fluid , chemistry , compressed fluid , bioreactor , propane , chromatography , solvent , supercritical fluid extraction , dilution , hydrostatic pressure , chemical engineering , organic chemistry , thermodynamics , physics , engineering
A novel continuous high‐pressure biphasic bioreactor was designed to investigate the toxicity of compressed and supercritical fluids on the thermophilic bacterium Clostridium thermocellum . Cultures were conducted at 1.8 and 7.0 MPa hydrostatic pressure and in the presence of compressed N 2 (7.0 MPa), gaseous (1.8 MPa) and supercritical ethane (7.0 MPa), and gaseous (1.8 MPa) and liquid (7.0 MPa) propane at a single dilution rate. No significant changes in metabolism or growth were observed in the presence of compressed N 2 relative to 7.0 MPa hydrostatic pressure, indicating that it acted as an inert fluid. However, dramatic inhibitions of growth and metabolism occurred in the presence of ethane and propane at 7.0 MPa. These inhibitions were reversed by depressurization from the supercritical (ethane) or liquid (propane) to gaseous state. Solvent toxicity by compressed and supercritical fluids was attributed to phase toxicity and was correlated with fluid density rather than conventional measures of toxicity ( log P o/w ). This biphasic reactor system facilitates investigations of solvent toxicity and dissolved gas effects on whole cells under elevated pressures. © 2004 Wiley Periodicals, Inc.