1067-4136/03/3405- $25.00 © 2003
Russian Journal of Ecology, Vol. 34, No. 5, 2003, pp. 303–308. Translated from Ekologiya, No. 5, 2003, pp. 341–346.
Original Russian Text Copyright © 2003 by Ilarionov, Nazarov, Kalachnikova.
Studies on the effects of soil pollution with oil on
the state of ecosystems are of both theoretical and prac-
tical importance, as environmental pollution with oil
hydrocarbons is extensive. Numerous studies show that
oil pollution has a strong adverse effect on plant growth
and development (Shilova, 1977, 1988; Demidenko
, 1983; Gasheva
, 1990). This is due primarily
to the toxicity of oil hydrocarbons and changes in phys-
icochemical properties of the soil (Guzev
Some studies (Oborin
, 1988; Guzev
, 1996) have demonstrated that the
heavy fractions of oil hydrocarbons are responsible for
the increasing hydrophobicity of the soil and other
changes in its physicochemical properties, whereas
light fractions are responsible for its direct toxic effect
on plants. In addition, the oil ﬁlm on the surface of soil
particles interferes with the migration of mobile forms
of phosphorus, nitrogen, and potassium into the soil
solution and, thus, may cause plant inhibition due to
nutrient deﬁciency (Khaziev
However, the factor of microbial poisoning—the
accumulation of toxic metabolites produced by micro-
organisms in the oil-polluted soil—has not yet been
taken into account. It is known that oil pollution of the
soil leads to changes in its microbial community
, 1989; Zvyagintsev
, 1989). This is
accompanied by an increase in the numbers and bio-
mass of saprotrophic micromycetes (Ismailov, 1988;
, 1988; Kireeva and Novoselova, 1996).
These microorganisms are the main producers of tox-
ins, and their increasing abundance in the soil causes an
increase in its phytoxicity (Berestetskii and Nadkerech-
nyi, 1978; Mirchink, 1988). The main role in microbial
soil poisoning supposedly belongs to toxin-producing
microorganisms inhabiting the rhizosphere, i.e., the soil
space under the inﬂuence of plant roots (Voznyak-
ovskaya, 1976). The microbial poisoning of the oil-pol-
luted soil may be highly important for the manifestation
of its phytotoxic properties (Mirchink, 1988). However,
neither this assumption nor the effects of oil pollution
on saprotrophic micromycetes of the rhizosphere have
been proven experimentally.
The purpose of this study was to investigate the
effects of oil pollution on micromycetes of the rhizo-
sphere and their role in the increase of soil phytoxicity.
OBJECTS AND METHODS
Studies were performed under laboratory condi-
tions and in the ﬁeld. The main object was the microf-
lora of the rhizosphere of meadow clover (
L.) and smooth brome (
(Leys.) Holub.) growing on the loamy sod-podzolic
soil. The humus content of the soil was 4.8%, and its
aqueous extract had pH 6.3.
In the laboratory, the plants were cultivated in the
vessels containing 3 kg of soil (100 plants in each). Soil
moisture was maintained at 60% of the total moisture
capacity, and temperature was
. To reduce the
loss of seedlings due to disturbances of moistening and
aeration in the polluted soil, plant seeds were soaked
for 24 h in distilled water and placed on the soil surface.
Field experiments were performed at the biological sta-
tion located in Dobryanskii raion of Perm oblast. Soil
samples for assessing the numbers of microorganisms
in the edaphosphere and rhizosphere of cultivated
plants were taken 14 days after their germination.
Soil phytoxicity was estimated from the germina-
tion rate, survival, and air-dry biomass of cultivated
, 1986; Grodzinskii, 1991; Khali-
, 1996; Petukhov
, 2000). In these exper-
was used as a test plant.
The Role of Micromycetes in the Phytotoxicity
of Crude Oil-Polluted Soils
S. A. Ilarionov, A. V. Nazarov, and I. G. Kalachnikova
Institute of Ecology and Genetics of Microorganisms, Ural Division, Russian Academy of Sciences, ul. Goleva 13,
Perm, 614081 Russia
Received August 9, 2002
—The microbe–plant interaction in soil under crude oil pollution was studied in Perm oblast, the
Cisural Region. In the rhizosphere of plants growing in the oil-polluted soil, an increased abundance of non-
symbiotic saprotrophic micromycetes was recorded. Under conditions of crude oil pollution, the development
of these microorganisms in the rhizosphere proved to have a strong adverse effect on the plants due to produc-
tion of mycotoxins.
: microbial soil poisoning, oil pollution, soil phytoxicity.