The biosorption of Cu(II), Zn(II) and Ni(II) by microscopic green algae Chlorella kessleri was investigated using batch experiments. Biosorption studies with single and multi ion solutions were carried out to study the effect of several ions on the biosorption of selected metal. The influence of zinc and nickel on copper biosorption, copper and nickel on zinc biosorption and zinc and copper on nickel biosorption were investigated. The Langmuir and Freundlich model were used to describe the adsorption equilibrium of studied metals on Chlorella kessleri biomass. Based on the experimental results it was found that the presence of copper increased the biosorption capacity of zinc from 48.6 mg/g to 96.8 mg/g and nickel from 29.3 mg/g to 62.7 mg/g, respectively. However, the presence of nickel decreased the biosorption capacity of zinc from 48.6 mg/g to 31.7 mg/g.
The evaluation of the toxicity and stress caused by heavy metals on plants is very important part of the phytoremediation research. Several physiological parameters can be used to assess the heavy metalinduced stress such as germination, plant growth and biomass production, photosynthetic pigments, antioxidant enzymes or antioxidants. Published results of measured physiological parameters in plants exposed to metals were characterized from of the negative effects of metals point of view and compared with the experimental study of the metal (Cu, Cd, Zn) toxicity in flax (Linum usitatissimum) and China aster (Callistephus chinensis) using the biochemical tests under the laboratory conditions. The germination and biomass production of C. chinensis significantly decreased with the increase of metal concentration which is considered a very typical response, however in L. usitatissimum slight stimulation of germination and biomass production at low metal content was observed. From the two studied plants C. chinensis expressed typical symptoms of the heavy metal toxicity including the decrease of total chlorophyll, chlorophylls a, b. On the contrary, heavy metal ions affected positively the physiological parameters of L. usitatissimum when low metal concentrations were added for example slight increase of the chlorophyll concentration in leaves was recorded. The decrease of the chlorophyll content was observed only at the high metal content. On the other hand, the typical response of plants on the heavy metal stress - the increase in peroxidase activity - was observed only for L. usitatissimum but not for C. chinensis that in all other tests showed significant toxicity symptoms. So if only one physiological parameter would be considered incorrect interpretation could be concluded. With the increase of phytoremediation practical applications the more systematic tests of heavy metal stress are necessary to help scientists working in that field correctly interpret their results and understand the plant behaviour.
The acidic functional groups of the cell wall of native algae Parachlorella kessleri were evaluated by potentiometric titrations. The Gran´s method was applied to determination of the total, strong, weak and very weak acidities. The total organic acidity obtained for biomass was 3.93 mmol g-1, the largest content belonged to the strong acidic groups (2.13 mmol g-1) together with the weak acidic carboxylic groups (1.28 mmol g-1). Very weak acidities represented by the amine groups (0.52 mmol g-1) did not exceed 14% and they formed the lowest numerous part of all acidic functional groups.
Many organisms or their extracts have the ability to reduce Ag+ ions to Ag0 and stabilize them what results in nanoparticle formation in solution. The aim of the article was to study the influence of two selected parameters - initial silver concentration and culture age, on Ag nanoparticles production by green algae Parachlorella kessleri. The presence of Ag nanoparticles in the solution was confirmed by the UV-vis spectroscopy and TEM analyses. Typical curve with the peak at app. 420 nm was found for nanoparticles produced by algae. While culture age did not have any significant effect, the initial silver concentration had significant influence on nanoparticle production which influenced the rate of nanoparticle production, their amount, their size and stability, as well
Through their metabolic activities microorganisms produce a large variety of products that may contribute to corrosion of different materials, including metals. The goal of this work was to monitor selected factors important in terms of corrosion or bio-corrosion, namely location, soil and the presence of water in four parts of the transit gas line passing through Slovakia, and subsequently to identify the level of risk of bio-corrosion. The analysis results from monitored locations indicated that in terms of bio-corrosion, the highest risk was in Zemplínské Hradiště 1 and Slivník trenches located in Eastern Slovakia and in Tomášová 1, 2 and 3 trenches located in the south of Slovakia.
Bioleaching processes were used to solubilize metals (Cu, Ni, Zn and Al) from printed circuit boards (PCBs). In this study, a PCBs-adapted pure culture of Acidithiobacillus ferrooxidans, pure culture of Acidithiobacillus thiooxidans and PCBs-adapted mixed culture of A. ferrooxidans and A. thiooxidans were used for recovery of the metals. The study showed that the mixed bacterial culture has the greatest potential to dissolve metals. The maximum metal bioleaching efficiencies were found to be 100, 92, 89 and 20% of Cu, Ni, Zn and Al, respectively. The mixed culture revealed higher bacterial stability. The main factor responsible for high metal recovery was the ability of the mixed culture to maintain the low pH during the whole process. The pure culture of A. thiooxidans had no significant effect on metal bioleaching from PCBs.
In general, Ag+ ions and AgNPs are considered to be the most toxic for bacterial cells and less toxic for higher organisms. In the present work inhibitory effects of biologically prepared silver nanoparticles on the growth of bacteria E. coli CCM 3954 and Staphylococcus aureus CCM 3953, green microscopic alga Parachlorella kessleri LARG/1 and seed germination and root growth of plant Sinapis alba seeds were investigated. Surprisingly, silver nanoparticles showed much stronger inhibitory effects on plant seed germination and root growth than on the bacterial growth. At concentration of 75 mg/l AgNPs both seed germination and root growth of Sinapis alba was inhibited whereas inhibition of the growth of E. coli and S. aureus was observed at >195 mg/l. Growth inhibition of alga Parachlorella kessleri was recorded at 300 mg/l AgNPs concentration. The inhibitory effect of silver ions was much higher compared to silver nanoparticles. Even 20 mg/l concentration of Ag+ ions inhibited the root growth and concentration > 45 mg/l inhibited germination of Sinapis alba seeds. Inhibition zones in both studied bacteria were found at concentration > 140 mg/l.
In the present work the Ni and Cd extraction from the electrode material of spent Ni-Cd batteries by bioleaching using the bacteria Acidithiobacillus ferrooxidans was examined. The possibility of the use of the bacteria for both the Ni and Cd recovery was analyzed. The anode of Ni-Cd batteries contains Ni0, Ni(OH)2, Cd0 and Cd(OH)2. The cathode is covered by nickel hydroxides and nickel oxy-hydroxides. The pH values and content of Ni and Cd in the solution were monitored throughout the experiment (the initial pH was 1.5, the experiment took 28 days). The bioleaching efficiency of Ni and Cd from anode powder reached 5.5% and 98%, respectively. During the cathode powder bioleaching Ni and Cd efficiency reached 45% and 100%, respectively. Throughout the bioleaching process mainly the dissolution of hydroxides occurred meanwhile Ni0 leaching was not observed. The AAS analysis was used to analyze the amount of Ni and Cd in the solutions. The amount of Ni and Cd present in the solid samples before and after bioleaching was examined using X-ray analysis.
Sulphur-oxidising autotrophic bacterial communities in deep biosphere from weathered ore samples from active gold mine Hodruša-Hámre, Slovakia were analysed using cultivation approach followed by DNA extraction, PCR amplification and 16S rRNA gene analyses. Indirect measurement of pH changes in cultivation media evidenced the presence of acidophilic bacteria with active production of acids. The decrease of pH was observed at the beginning of isolation and later pH in range of 1.5 – 2 was maintained in both, sulphuric acid and thiosulphate, media. The presence of homogenous population of gram-negative rods was proved by Gram staining. Molecular analyses have revealed that the population of sulphur-oxidising bacteria in gold mine is dominated by a single species of Aciditiobacillus genus, identified as A. albertensis, suggesting the low level of autotrophic bacteria diversity in deep deposits. For the first time this species was isolated from weathered rocks of a gold mine subsurface environment.
The genus Acidithiobacillus comprises 7 species of Gram-negative obligatory acidophilic chemolithotrophic bacteria that derive energy mainly from the oxidation of reduced sulphur compounds. Four of the species also catalyse the dissimilatory oxidation of ferrous iron while three (A. thiooxidans, A. albertensis, and A. caldus) do not. Bacteria from the genus Acidithiobacillus are often associated with mineral biotechnologies (biomining) and acid mine drainage. While acceleration of mineral solubilisation is a positive aspect in environmental biotechnologies, it is undesirable in acid mine drainage with strong negative ecological impact and there is profound interest in genetics and genomics of these bacteria. Representatives of Acidithiobacillus genus occur world-wide, however there are limited data on Acidithiobacillus spp. variability from Slovakia. In our work the variability of Acidithiobacillus spp., from Slovakia was analysed and the presence of A ferrooxidans was detected. In addition, for the first time we report here on the occurrence of A. albertensis as well. Comparative analyses confirmed pronounced genetic and genomic diversity within the genus, especially within A. ferrooxidans and A. thioxidans complexes. Based on data presented, several Acidithiobacillus species could be considered as a complex species and the description of several new species is very probable in the near future.