Agnieszka Wolińska

Response of soil catalase activity to chromium contamination

The impact of chromium(III) and (VI) forms on soil catalase activity was presented. The Orthic Podzol, Haplic Phaeozem and Mollic Gleysol from different depths were used in the experiment. The soil samples were amended with solution of Cr(III) using CrCl3, and with Cr(VI) using K2Cr2O7 in the concentration range from 0 to 20 mg/kg, whereas the samples without the addition of chromium served as control. Catalase activity was assayed by one of the commonly used spectrophotometric methods. As it was demonstrated in the experiment, both Cr(III) and Cr(VI) have an ability to reduce soil catalase activity. A chromium dosage of 20 mg/kg caused the inhibition of catalase activity and the corresponding contamination levels ranged from 75% to 92% for Cr(III) and 68% to 76% for Cr(VI), with relation to the control. Catalase activity reached maximum in the soil material from surface layers (0-25 cm), typically characterized by the highest content of organic matter creating favorable conditions for microorganisms.

Potential for Aerobic Methane Oxidation in Carboniferous Coal Measures

Carbon (C), geologically sequestered in coal, is gradually released to the atmosphere as CH4 and CO2. Recent anthropogenic activity (coal mining) has rapidly increased the rate of C reallocation from coal deposits into the atmosphere, which has deleterious effect on the climate as both gases are effective infrared absorbers. In the current study we demonstrate that the coal bearing sedimentary rocks possess potential of biological methane oxidation. Viable methanotrophic bacteria, capable of methane oxidation at ambient air and a range of methane concentrations were found in coalbearing formations of the Upper Silesian (USCB) and Lublin Coal Basins (LCB). Factors controlling activity of the aerobic methanotrophic bacteria in the deep subsurface such as, depth, methane concentration, available electron acceptors, moisture and nutrients availability were investigated along with paleoenvironmental factors (temperature changes during and after burial and paleohydrological infiltration). The distribution and activity of the methanotrophic bacteria in the deep subsurface were found to be influenced by geological conditions among which evolution of paleotemperatures and paleohydrological conditions play a predominant role. The data presented along with analysis of molecular composition of the coalbed gases in various coal basins worldwide has led to the conclusion that aerobic methanotrophy may be a widespread process, which, to our knowledge, so far has not been included in investigations concerning C cycling in the subsurface.

Microbial biodiversity in arable soils is affected by agricultural practices

Abstract The aim of the study was to examine the differences in microbial community structure as a result of agricultural practices. Sixteen samples of cultivated and the same number of non-cultivated soils were selected. Gel bands were identified using the GelCompar software to create the presence-absence matrix, where each band represented a bacterial operational taxonomic unit. The data were used for principal-component analysis and additionally, the Shannon- Weaver index of general diversity, Simpson index of dominance and Simpson index of diversity were calculated. Denaturing gradient gel electrophoresis profiles clearly indicated differentiation of tested samples into two clusters: cultivated and non-cultivated soils. Greater numbers of dominant operational taxonomic units (65) in non-cultivated soils were noted compared to cultivated soils (47 operational taxonomic units). This implies that there was a reduction of dominant bacterial operational taxonomic units by nearly 30% in cultivated soils. Simpson dominance index expressing the number of species weighted by their abundance amounted to 1.22 in cultivated soils, whereas a 3-fold higher value (3.38) was observed in non-cultivated soils. Land-use practices seemed to be a important factors affected on biodiversity, because more than soil type determined the clustering into groups.

Easily degradable carbon – an indicator of microbial hotspots and soil degradation

Abstract The effect of arable soil was quantified against non-cultivated soil on easily degradable carbon and other selected microbiological factors, i.e. soil microbial biomass, respiration activity, and dehydrogenase activity. The intent was to ascertain whether easily degradable carbo can be useful as a sensitive indicator of both soil biological degradation and microbial hot-spots indication. As a result, it was found that soil respiration activity was significantly higher (p <0.0001) in all controls, ranging between 30-60 vs. 11.5-23.7 μmol CO2 kg d.m.−1 h−1 for the arable soils. Dehydrogenase activity was significantly lower in the arable soil (down to 35-40% of the control values, p <0.001) varying depending on the soil type. The microbial biomass was also significantly higher at the non-cultivated soil (512-2807 vs. 416-1429 µg g−1 d.m., p <0.001), while easily degradable carbon ranged between 620-1209 mg kg−1 non-cultivated soil and 497-877 mg kg−1 arable soil (p <0.0001). It was demonstrated that agricultural practices affected soil properties by significantly reducing the levels of the studied parameters in relation to the control soils. The significant correlations of easily degradable carbon-respiration activity (ρ = 0.77*), easily degradable carbon-dehydrogenase activity (ρ = 0.42*), and easily degradable carbon-microbial biomass (ρ = 0.53*) reveal that easily degradable carbon is a novel, suitable factor indicative of soil biological degradation. It, therefore, could be used for evaluating the degree of soil degradation and for choosing a proper management procedure.

Community-level physiological profiles of microorganisms inhabiting soil contaminated with heavy metals

Abstract The aim of the study was to assess the differences in the bacterial community physiological profiles in soils contaminated with heavy metals versus soils without metal contaminations. The study’s contaminated soil originated from the surrounding area of the Szopienice non-ferrous metal smelter (Silesia Region, Poland). The control was soil unexposed to heavy metals. Metal concentration was appraised by flame atomic absorption spectrometry, whereas the the community-level physiological profile was determined with the Biolog EcoPlatesTM system. The soil microbiological activity in both sites was also assessed via dehydrogenase activity. The mean concentrations of metals (Cd and Zn) in contaminated soil samples were in a range from 147.27 to 12265.42 mg kg−1, and the heavy metal contamination brought about a situation where dehydrogenase activity inhibition was observed mostly in the soil surface layers. Our results demonstrated that there is diversity in the physiological profiles of microorganisms inhabiting contaminated and colntrol soils; therefore, for assessment purposes, these were treated as two clusters. Cluster I included colntrol soil samples in which microbial communities utilised most of the available substrates. Cluster II incorporated contaminated soil samples in which a smaller number of the tested substrates was utilised by the contained microorganisms. The physiological profiles of micro-organisms inhabiting the contaminated and the colntrol soils are distinctly different.

DNA Contents in Soil Contaminated with Heavy Metals

Abstract: The study was performed to show how industrial activity affected soil quality in terms of soil DNA quality and quantity as well as soil characteristics. Soil material originated from an urban area of the Silesia Region (SW Poland). The soil characteristics were estimated: texture, moisture, pH, redox potential (Eh), and total carbon content (TOC), followed by determination of selected heavy metals (Pb, Cd, Zn, Cr, Fe, Cu). The last step was the isolation of soil DNA, its concentration and identification of microorganisms. The results showed that although the studied soil was heavily contaminated with heavy metals, there were still some metal-resistant microorganisms able to sustain soil activity. Moreover, these organisms are not present in the NCBI database, which encourages further studies aimed at identification of new organisms that may be useful in research of metal resistance as well as soil reclamation and remediation. Keywords: Heavy metal, metal resistant bacteria, soil, t-DNA.