3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
P45 bIOREMEDIATION OF bOTTON SEDIMENTS
uSING bACillus MegATeriuM AND
bACillus Cereus
KATARínA JABLOnOVSKá and IVETA ŠTYRIAKOVá
Department of Biotechnology, Institute of Geotechnice of
Slovac Academy of Sciences, Watsonova 45, 043 53 Kosice,
Slovak Republic
jablonov@saske.sk
Introduction
The water reservoir Ružín I. lies in an area, which for
several centuries has been known for mining and metallurgical
activities. The bottom sediments are contaminated
with heavy metals, in the concrete with Hg, Cu, Mn, Zn, ni
and Cd, which were washed away into the water reservoir
from locations of former mining activities (Cicmanova et al.,
2003). Enhanced amounts of heavy metals preclude of direct
utilization of sediments in agricultural and building industry
and also in ground shaping (Brehuv, J., 2000).
The availing of bioleaching techniques on mobilization
of heavy metals from sediments seems to be an appropriate
manner of retreatment. In this attempt, besides indigenous
microflora bacterial species Bacillus megaterium and Bacillus
cereus was used. These bacterial species were izolate
from the soil matrix of sampling place Hornád-inlet. Because
heavy metals are increasingly found in microbial habitats due
to natural and industrial processes, microbes have envolved
several mechanisms to tolerate the presence of heavy metals
(by either efflux, complexation, or reduction of metal ions) or
to use them as terminal electron acceptors in anaerobic respiration
(Senenska-Pobel S. et al, 1998). The objectives of this
work were to determine the differences of influence Bacillus
cereus and Bacillus megaterium on leachibility ni and Cd
ions from polluted sediments.
Experimental
Sediment samples were obtained from the botton of
water reservoir Ružín I in Slovakia at differend depths (20
and 40 cm). Heavy metals composition is given in Table I.
Biological leaching of the sample material was carried
out in conical flasks with 30 g sediment and 600 ml Ashby´s
medium. The Ashby´s medium contained (per liter) 0.2 g
urea, 1 g K 2 HPO 4 , 0.075 g naCl. Glucosse (2 g dm –3 ) was
added as the organic substrate. The flasks were inoculated
with Bacillus megaterium and Bacillus cereus cultures, originally
isolated from the sediment of water reservoir Ružín I.
in Slovakia. The two strains were purified and followed by
streak plating on nutrient agar cultures. The isolates were
identified with the BBL Crystal Identification System (Becton
Dickinson, USA).
The flasks were incubated under static conditions for
6 months at 25 °C in the dark. Appropriate abiotic controls
were included in these experiments. Changes in the chemical
composition of solid and liquid phases were measured by
atomic absorption spectrometry (Varian AA240-Z with GTA-
s670
120 a AA240-FS). The particle size distribution was measured
by the laser radiation scattering using a model 22 Laser-
Particle – Sizer Analysette (Fritsch GmbH, Idar-Oberstein,
Germany).
Results
The ni and Cd concentrations of sediments taken from
20 and 40 cm depth layers are shown in Table I. The amount
of investigated heavy metals overrun the limit values given
by Metodical Instruction ministry of Environment – Slovak
Republic no. 491/2002. The established values give information
about the potential risk of ni and Cd releasing and about
surrounding and outlying contamination ecosystems.
Table I
The results of surface layer analysis of sediments from 20 cm
depth and their comparison with Metodical Instruction Ministry
of Environment – Slovak Republic no. 491/2002
Element ni Cd
Depth [mg kg –1 ]
20 cm 87 1.2
40 cm 86 0.9
MIME-SR MPC 44 12.0
no. 491/2002 TV 35 0.8
Table II
Effectivity of bioleaching process with application of Bacillus
megaterium and Bacillus cereus
element
Before BL
[mg kg –1 ]
After BL
Bacillus
megaterium
[mg kg –1 ]
After BL
Bacillus cereus
[mg kg –1 ]
ni 86.0 79.0 70.0
Cd 1.2 0.8 1.0
Fig.1. depicts the kinetic of the bioleaching process of
ni from sediment sample taken from the depth 20 cm. ni
concentration was observed during bioleaching in soluble
form. The curves present the differences between the effectivity
of bioleaching processes in two bacterial systems,
Bacillus megaterium and Bacillus cereus. The above mentioned
processes took 54 days. The maximum concentration
of eluted ni was achieved in the 21 th day (B. megaterium)
and by B. cereus in the 14 th day. The maximum concentration
ni in B. cereus system achieved 1,247.3 ng ml –1 and in B.
megaterium system 1,087.5 ng ml –1 . The results refer to the
higher effectivity in the case of application of the bacterial
strain Bacillus cereus.
Fig. 2. presents the kinetic curves of the bioleaching
process of Cd from the sediment sample (20 cm depth).
The Cd leaching processes were carried out under the same
conditions as in the case of the ni leaching. In the presence
of Bacillus megaterium an increased concentration
of Cd was detected. The medium in the 14th day contained