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Title: Evidence for an anaerobic syntrophic benzoate degradation threshold and isolation of the syntrophic benzoate degrader

An anaerobic, motile, gram-negative, rod-shaped, syntrophic. benzoate-degrading bacterium, strain SB. was isolated in pure culture with crotonate as the energy source. Benzoate was degraded only in association with an H{sub 2}-using bacterium. The kinetics of benzoate degradation by cell suspensions of strain SB in coculture with Desulfovibrio strain G-11 was studied by using progress curve analysis. The coculture degraded benzoate to a threshold concentration of 214 nM to 6.5 {mu}M, with no further benzoate degradation observed even after extended incubation times. The value of the threshold depended on the amount of benzoate added and, consequently, the amount of acetate produced. The addition of sodium acetate. but not that of sodium chloride, affected the threshold value; higher acetate concentrations resulted in higher threshold values for benzoate. When a cell suspension that had reached a threshold benzoate concentration was reamended with benzoate, benzoate was used without a lag. The hydrogen partial pressure was very low and formate was not detected in cell suspensions that had degraded benzoate to a threshold value. The Gibbs free energy change calculations showed that the degradation of benzoate was favorable when the threshold was reached. These studies showed that the threshold for benzoate degradation was not causedmore » by nutritional limitations. the loss of metabolic activity, or inhibition by hydrogen or formate. The data are consistent with a thermodynamic explanation for the existence of a threshold, but a kinetic explanation based on acetate inhibition may also account for the existence of a threshold.« less
Authors:
; ;  [1]
  1. Univ. of Oklahoma, Norman, OK (United States)
Publication Date:
OSTI Identifier:
621395
DOE Contract Number:
FG05-89ER14003
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied and Environmental Microbiology; Journal Volume: 61; Journal Issue: 2; Other Information: PBD: Feb 1995
Country of Publication:
United States
Language:
English
Subject:
55 BIOLOGY AND MEDICINE, BASIC STUDIES; BIODEGRADATION; AROMATICS; POLLUTANTS; ACETATES; SODIUM COMPOUNDS; BENZOIC ACID; SALTS; ANAEROBIC CONDITIONS; BACTERIA