1067-4136/04/3503- © 2004
Russian Journal of Ecology, Vol. 35, No. 3, 2004, pp. 176–180. Translated from Ekologiya, No. 3, 2004, pp. 205–209.
Original Russian Text Copyright © 2004 by Izvekova, Lapteva.
The bacterial ﬂora is an obligatory companion of
complex organisms. Together with physical and chem-
ical factors, microorganisms and parasites populating
the intestine form the endoecological environment of
ﬁsh. Therefore the relationships between the compo-
nents of this environment should be always taken into
consideration. At present, the scheme of digestion in
ﬁsh is assumed to consist of six links, one link being
symbiotic digestion occurring with the involvement of
intestinal microﬂora (Kuz’mina
, 2000). The sym-
biotic microﬂora produces nutrients that do not require
further hydrolysis, such as amino acids, glucose, fatty
acids, etc. (Ugolev, 1985). The intestinal microﬂora
synthesizes many vitamins necessary for life activities
both of the host and parasite (Shishova-Kasatochkina
and Leutskaya, 1979).
There is extensive literature on the quantitative and
species composition of the intestinal microﬂora of ver-
tebrates, including ﬁsh (Lubianskiené
Cahill, 1990; Clements, 1997). An important aspect in
the investigation of this microﬂora is its role in nutrition
due to the release of extracellular enzymes participating
in the hydrolysis of biopolymers. For example, cellu-
lase activity obviously accounted for by the intestinal
microﬂora was detected in the stomachs of 17 out of
62 ﬁsh species studied (Cahill, 1990). Relationships
between the microﬂora and helminths found in the
intestine have been poorly studied (Mettrick and Pod-
esta, 1974; Arme
, 1983). Publications available to
us contain no information on the radial gradient of the
microﬂora in ﬁsh intestines and parasitic cestodes.
Likewise, there are no data on the microﬂora and helm-
) connected with the
body cavity of ﬁsh.
The aim of the present study was to study the sym-
biotic microﬂora associated with the digestive-trans-
port surfaces of the intestines of some freshwater ﬁsh
species and their endoparasitic cestodes.
MATERIAL AND METHODS
We studied the mucosa of the intestines of pike
) and burbot (
); their parasitic ces-
; and, in addition, plerocercoids of
living in the body cavity of bream (
The ﬁsh were captured in the Rybinsk Reservoir in the
season of active feeding: burbot, in January; pike, in
April–May; and bream, in July–August. As the activity
of the digestive enzymes of ﬁsh depends on many fac-
tors, including age (Ugolev and Kuz’mina, 1993), sim-
ilar size–age groups of each ﬁsh species were used in
investigations of the intestinal microﬂora (pike with a
body length of 300–380 mm; burbot, 400–500 mm; and
bream, 230–280 mm). Five to ten worms were taken out
of the pike and burbot intestines in each experiment; the
weight of parasites ranged from 250 to 450 mg for
and from 790 to 1520 mg for
One plerocercoid of
was taken out from
the body cavity of each bream; the size and weight of
these worms ranged from 150 to 250 mm and from
8.86 to 17.78 g.
In each experiment, 2- to 3-cm pieces of the middle
part of the ﬁsh intestine and whole worms were investi-
gated. Prior to dissection, the intestines were washed in
alcohol to sterilize the surface.
taken out of the body cavity of ﬁsh whose surface was
wiped with alcohol. Washings from ﬁsh intestines and
worm surface for microbiological analysis were
obtained using a scheme of successive enzyme desorp-
tion from fragments of the intestine (Kuz’mina, 1976).
The fragments of the intestine and worms were
placed in ﬂasks with 15 ml of sterile Ringer’s solution
Microflora Associated with the Digestive-Transport Surfaces
of Fish and Their Parasitic Cestodes
G. I. Izvekova and N. A. Lapteva
Papanin Institute of the Biology of Inland Waters, Russian Academy of Sciences,
Borok, Nekouzskii raion, Yaroslavl oblast, 152742 Russia
Received January 5, 2003
—The symbiotic microﬂora is described that is associated to various degrees with the digestive-trans-
port surfaces of pike and burbot and their parasitic cestodes
, respectively, as well
plerocercoids from the body cavity of bream. Some of these bacteria possess amylolytic and
proteolytic activity, which indicates their participation in both the digestion of the host and of the parasite.
: ﬁsh, cestodes, symbiotic microﬂora, abundance, biomass, proteolytic activity, amylolytic activity.