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Applied and Environmental Microbiology, March 1999, p. 1152-1160, Vol. 65, No. 3
Subdepartment of Environmental Technology,
Department of Agricultural, Environmental, and Systems Technology,
Wageningen Agricultural University, 6703 HD Wageningen, The
Netherlands
Received 8 June 1998/Accepted 15 December 1998
Three methanogenic enrichment cultures, grown on
ortho-phthalate, iso-phthalate, or
terephthalate were obtained from digested sewage sludge or
methanogenic granular sludge. Cultures grown on one of the
phthalate isomers were not capable of degrading the other
phthalate isomers. All three cultures had the ability to degrade
benzoate. Maximum specific growth rates (µSmax) and
biomass yields (YXtotS) of the mixed
cultures were determined by using both the phthalate
isomers and benzoate as substrates. Comparable values for these
parameters were found for all three cultures. Values for
µSmax and YXtotS were
higher for growth on benzoate compared to the phthalate isomers.
Based on measured and estimated values for the microbial yield of the
methanogens in the mixed culture, specific yields for the phthalate
and benzoate fermenting organisms were calculated. A kinetic model,
involving three microbial species, was developed to predict
intermediate acetate and hydrogen accumulation and the final production
of methane. Values for the ratio of the concentrations of methanogenic
organisms, versus the phthalate isomer and benzoate fermenting
organisms, and apparent half-saturation constants (KS) for
the methanogens were calculated. By using this combination of measured
and estimated parameter values, a reasonable description of
intermediate accumulation and methane formation was obtained,
with the initial concentration of phthalate fermenting organisms
being the only variable. The energetic efficiency for growth of
the fermenting organisms on the phthalate isomers was calculated to
be significantly smaller than for growth on benzoate.
0099-2240/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Anaerobic Degradation of Phthalate Isomers by
Methanogenic Consortia
*
Corresponding author. Mailing address: Wageningen
Agricultural University, Department of Agricultural, Environmental and
Systems Technology, Subdepartment of Environmental Technology,
"Biotechnion" Bomenweg 2, 6703 HD Wageningen, The Netherlands.
Phone: (31-317) 483798. Fax: (31-317) 482108. E-mail:
robbert.kleerebezem{at}algemeen.mt.wau.nl.
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