3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
Fig. 1. basic kinetic of the bioleaching Ni, sediment depth
– 20 cm, bM – bacillus megaterium, bC – bacillus cereus
14.2 ng ml –1 Cd. These experiments give a considerable evidence
about the differences of metabolic activity of two bacterial
strains, Bacillus cereus and Bacillus megaterium. The
results show more effective application of Bacillus megaterium,
because of the shorter time needed to Cd releasing
into the solution. The concentration of Cd in the medium is
approximately 3 times higher as in the case of obtained from
the depth 40 cm were proved through the same experimental
processes as the sediment from the 20 cm, but the behaviour
and the results of bioleaching ni and Cd were in both cases
the same (Data not showed).
Fig. 2. basic kinetic of the bioleaching Cd, sediment depth
– 20 cm, bM – bacillus megaterium, bC – bacillus cereus
pH of bioleaching system has a direct relationship to the
mobility of metals relating to their solubility. The concentration
of cations in sediment solution usually increase greatly
under a low pH condition (Wu et al., 2006). The decrease
of pH values was achieved through bacterial production of
acetic acid, butyric acid, pyruvic acid, lactic acid and formic
acid (Styriakkova et al, 99). Fig. 5 presented the decreasing
of pH values in both B. cereus and B. megaterium bioleaching
s671
Fig. 3. The decrease of ph in course of bioleaching. bM – bioleaching
system with the application of bacillus megaterium
inoculum bC – bioleaching system with the application of bacillus
cereus inoculum
systems. The measurements indicate a markedly change in
the pH solution during the first 20 days from pH 7 to 4.6
(B. cereus) and 4,9 (B. megaterium). In the next experiment a
relatively constant level pH values are shown.
Conclusions
Our study demonstrated that Bacillus spp. related to the
species Bacillus megaterium and Bacillus cereus, presented
and isolated from heavy metals contaminated sediments,
are able to release ni and Cd ions from polluted sediments.
This kind of heterotrophyc microorganisms may pose positive
impact on the availability and mobility of ni and Cd and
other heavy metals in sediments from water reservoir Ružín
I . In this study Cd ions seems to be easier leached through
Bacillus megaterium strain than Bacillus cereus according to
their metabolic activity and adaptability to the Cd polluted
environment. The ni ions was easier leached with application
of Bacillus cerus strain. In general, the bacteria innoculation
enhanced the leachability of ni and Cd. The possible mechanisms
may also be responsible for the integrated effects of
lowering pH through bacteria metabolism and production of
organic acids.
This work has been supported by VEGA Agency supporting
the projects No-2/0049/08.
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