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Appl. Environ. Microbiol., Oct 1996, 3605-3613, Vol 62, No. 10
R Rabus, M Fukui, H Wilkes and F Widdle
A mesophilic sulfate-reducing enrichment culture growing anaerobically on
crude oil was used as a model system to study which nutritional types of
sulfate-reducing bacteria may develop on original petroleum constituents in
oil wells, tanks, and pipelines. Chemical analysis of oil hydrocarbons
during growth revealed depletion of toluene and o- xylene within 1 month
and of m-xylene, o-ethyltoluene, m-ethyltoluene, m-propyltoluene, and
m-isopropyltoluene within approximately 2 months. In anaerobic counting
series, the highest numbers of CFU (6 x 10(6) to 8 x 10(6) CFU ml-1) were
obtained with toluene and benzoate. Almost the same numbers were obtained
with lactate, a substrate often used for detection of the vibrio-shaped,
incompletely oxidizing Desulfovibrio sp. In the present study, however,
lactate yielded mostly colonies of oval to rod-shaped, completely
oxidizing, sulfate-reducing bacteria which were able to grow slowly on
toluene or crude oil. Desulfovibrio species were detected only at low
numbers (3 x 10(5) CFU ml-1). In agreement with this finding, a
fluorescently labeled, 16S rRNA-targeted oligonucleotide probe described in
the literature as specific for members of the Desulfovibrionaceae
(suggested family) hybridized only with a small portion (< 5%) of the
cells in the enrichment culture. These results are consistent with the
observation that known Desulfovibrio species do not utilize aromatic
hydrocarbons, the predominant substrates in the enrichment culture. All
known sulfate- reducing bacteria which utilize aromatic compounds belong to
a separate branch, the Desulfobacteriaceae (suggested family). Most members
of this family are complete oxidizers. For specific hybridization with
members of this branch, the probe had to be modified by a nucleotide
exchange. Indeed, this modified probe hybridized with more than 95% of the
cells in the enrichment culture. The results show that completely
oxidizing, alkylbenzene-utilizing sulfate-reducing bacteria rather than
Desulfovibrio species have to be considered in attempts to understand the
microbiology of sulfide production in oil wells, tanks, and pipelines when
no electron donors other than the indigenous oil constituents are
available.
Copyright © 1996, American Society for Microbiology
Degradative capacities and 16S rRNA-targeted whole-cell hybridization of sulfate-reducing bacteria in an anaerobic enrichment culture utilizing alkylbenzenes from crude oil
Max-Planck-Institut fur Marine Mikrobiologie, Bremen, Germany.
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