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ABSTRACT
The physiological interactions of microorganisms on the morphological and structural level of minerals accelerate their bio-geochemical decay, which as a result represents liberation of the elements into the environment. The studies of experimental bioleaching of selected synthetic minerals of lead in the laboratory conditions assess the activity of new bacterial isolates of Pseudomonas genus, originating from anthropogenic-contaminated sediments of settling basins with high contents of heavy metals. In all the bacteria the activities of heterotrophic mineral leaching processes were confirmed. The most efficient was the bacteria of P. chlororaphis ZK-1, which released 5.74 - 9.59 % of lead into the solution. The experiment results are discussed with respect to possible bio-transformations of lead in the environment and their significance in the prediction of solubilisation processes at the bacterial cell level.
Keywords: bioleaching, solubilisation, anglesite, cotunnite, Pseudomonas
INTRODUCTION
The physiological interactions of microorganisms at the morphological and structural level of minerals are conditioned by their biological activity. Learning about their mutual relations and dependencies helps to predict their behaviour in various systems. It has been established that the presence of microorganisms accelerates the biogeochemical degradation of minerals, which leads to the liberation of elements into the surrounding environment [3]. Increased mobility of elements in the given environment subsequently influences their bioavailability, transformation and form of occurrence in the chemical compounds [6].
The paper experimentally verifies bioleaching capacities of selected Pseudomonas bacterial strains and their efficiency in the release of toxic metals from synthetic minerals, namely anglesite and cotunnite, containing toxic lead. Based on the interactions in the [Pb-mineral-toxic metal-microorganism] system, it aims to quantify the morphological and structural changes in the solubilised minerals at the microscopic level.
MATERIALS AND METHODS
Secondary lead minerals, namely anglesite (PbSO4) and cotunnite (PbCh), were obtained in the form of synthetic crystalline substances (Penta, Czech Republic). It was verified the required stoichiometric composition, including their morphology, which was confirmed via SEM microscopy.
To identify the most effective microbial species, we used various types of bacteria from the Pseudomonas genus retrieved as new isolates from anthropogenically contaminated localities, namely by toxic arsenic [8], [11], [12]. Bioleaching experiments lasted for 30 days using the method of static cultivation at standard laboratory conditions. The efficiency of Pb bioleaching process was assessed in...