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Appl. Environ. Microbiol., 09 1996, 3371-3377, Vol 62, No. 9
HL Chang and L Alvarez-Cohen
The microbial degradation of chlorinated and nonchlorinated methanes,
ethanes, and ethanes by a mixed methane-oxidizing culture grown under
chemostat and batch conditions is evaluated and compared with that by two
pure methanotrophic strains: CAC1 (isolated from the mixed culture) and
Methylosinus trichosporium OB3b. With the exception of 1,1-
dichloroethylene, the transformation capacity (Tc) for each chlorinated
aliphatic hydrocarbon was generally found to be in inverse proportion to
its chlorine content within each aliphatic group (i.e., methanes, ethanes,
and ethenes), whereas similar trends were not observed for degradation rate
constants. Tc trends were similar for all methane- oxidizing cultures
tested. None of the cultures were able to degrade the fully chlorinated
aliphatics such as perchloroethylene and carbon tetrachloride. Of the four
cultures tested, the chemostat-grown mixed culture exhibited the highest Tc
for trichloroethylene, cis-1,2- dichloroethylene, tetrachloroethane,
1,1,1-trichloroethane, and 1,2- dichloroethane, whereas the pure
batch-grown OB3b culture exhibited the highest Tc for all other compounds
tested. The product toxicity of chlorinated aliphatic hydrocarbons in a
mixture containing multiple compounds was cumulative and predictable when
using parameters measured from the degradation of individual compounds. The
Tc for each chlorinated aliphatic hydrocarbon in a mixture (Tcmix) and the
total Tc for the mixture (sigma Tcmix) are functions of the individual Tc,
the initial substrate concentration (S0), and the first-order rate constant
(k/Ks) of each compound in the mixture, indicating the importance of
identifying the properties and compositions of all potentially degradable
compounds in a contaminant mixture.
Copyright © 1996, American Society for Microbiology
Biodegradation of individual and multiple chlorinated aliphatic hydrocarbons by methane-oxidizing cultures
Department of Civil and Environmental Engineering, University of California, Berkeley 94720-1710, USA.
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