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Competition between oxygen and nitrate respirations in continuous culture of Pseudomonas aeruginosa performing aerobic denitrification
Author(s) -
Chen Fan,
Xia Qing,
Ju LuKwang
Publication year - 2006
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.20812
Subject(s) - denitrification , nitrate , oxygen , chemistry , yield (engineering) , respiration , electron acceptor , electron donor , dilution , nitrogen , biochemistry , biology , botany , physics , organic chemistry , thermodynamics , catalysis
Continuous culture of P. aeruginosa was conducted with nitrate‐containing media under the dilution rates ( D ) of 0.026, 0.06, and 0.13/h and the dissolved oxygen concentrations (DO) of 0–2.2 mg/L. The bacterium performed simultaneous O 2 and nitrate respiration in all of the systems studied. For each D , the (apparent) cell yield from glucose ( Y X/S ) was lower at zero DO, but did not change substantially with non‐zero DO. In non‐zero DO systems, Y X/S increased with increasing D , and when fit with a model considering cell death, gave the following parameters: maximum cell yield Y X/S m = 0.49, maintenance coefficient M S = 0.029 (/h), and cell decay constant k d = 0.014/h. The same model failed to describe the behaviors of zero‐DO systems, where neither glucose nor nitrate was limiting and the limiting factor(s) remained unknown. The cell yield from accepted electron ( Y X/e ) was however relatively constant in all systems, and the energy yield per electron accepted via denitrification was estimated at ∼69% of that via O 2 respiration. A closer examination revealed that increasing DO enhanced O 2 respiration only at extremely low DO ( <0.05 mg/L), beyond which the increasing DO only slightly increased its weak inhibition on denitrification. While O 2 was the preferred electron acceptor, the fraction of electrons accepted via denitrification increased with increasing D . © 2006 Wiley Periodicals, Inc.