Zofia Stępniewska

Aerobic and anaerobic respiration in profiles of Polesie Lubelskie peatlands

Abstract Soil respiration is a very important factor influencing carbon deposition in peat and reflecting the intensity of soil organic matter decomposition, root respiration, and the ease of transporting gases to the surface. Carbon dioxide release from three different peat soil profiles (0-80 cm) of the Polesie Lubelskie Region (Eastern Poland) was analyzed under laboratory conditions. Peat samples were incubated at 5, 10, and 20°C in aerobic and anaerobic environments, and their CO2-evolution was analyzed up to 14 days. The respiration activity was found to be in the range of 0.013-0.497 g CO2 kg-1 DW d-1. The respiratory quotient was estimated to be in the range of 0.51-1.51, and the difference in respiration rates over 10°C ranged between 4.15 and 8.72 in aerobic and from 1.15 to 6.53 in anaerobic conditions. A strong influence of temperature, depth, the degree of peat decomposition, pH, and nitrate content on respiration activity was found. Lack of oxygen at low temperature caused higher respiration activity than under aerobic conditions. These results should be taken into account when the management of Polish peatlands is considered in the context of climate and carbon storage, and physicochemical properties of soil in relation to soil respiration activity are considered.

Effect of soil moisture and temperature on N2O and CO2 concentrations in soil irrigated with purified wastewater

Abstract Flooded organic soils are potentially important sources of greenhouse gases. The effect of soil temperature and moisture on the concentration of N2O and CO2 at two depths of organic soil flooded with two doses of purified wastewater was studied. Nitrous oxide concentrations at the 10-30 cm depth range were generally increased with an increase in soil moisture, showing dependence on the aeration status of soil. The maximum values of N2O concentrations were higher at the 50-100 than 10-30 cm depth range, but a similar pattern of increasing maximum values of N2O concentration with an increasing input of nitrogen in treatments at both depth ranges was observed. The maximum concentrations of carbon dioxide within the 50-100 cm depth range remained at a similar level in all treatments reaching 7.1-7.7%, which indicated weak relations with the input of water and nitrogen at this depth range. We conclude that the N2O and CO2 concentrations at 10-30 cm depths in the examined organic soil flooded with 600mm year-1 of purified wastewater exhibited a similar level as the concentrations in soil watered only by precipitation.

Protective effects of ectoine on behavioral, physiological and biochemical parameters of Daphnia magna subjected to hydrogen peroxide.

Ectoine (ECT) is an osmoprotectant produced by halophilic microorganisms inducing protective effects against various stressful factors. However, little is known about its influence on aquatic invertebrates subjected to hydrogen peroxide (H2O2)-a commonly used oxidative disinfectant. Therefore, the aim of our study was to determine the effects of H2O2 alone (at 5 and 10 mg/L) and in the combination with various concentrations of ECT (5, 10 and 25 mg/L) on behavioral, physiological and biochemical parameters of Daphnia magna. The following endpoints were determined: mortality, heart rate, thoracic limb movement, total glutathione (GSH)/oxidized glutathione (GSSG) ratio, catalase (CAT) activity and nitric oxide (NOx) level. The study showed that daphnids exposed to the combination of H2O2+ECT showed decreased mortality, attenuated inhibition of heart rate and thoracic limb activity, less decreased GSH/GSSG ratio, lower stimulation of CAT activity and NOx level when compared to the crustaceans exposed to H2O2 alone. The most pronounced alleviation of toxic effects was observed in the combination of 5 mg/L H2O2+25 mg/L ECT. The results suggest that protective effects of ECT in D. magna subjected to H2O2 may be related to antioxidative properties of the osmoprotectant.

Effects of ectoine on behavioural, physiological and biochemical parameters of Daphnia magna

Ectoine (ECT) is a compatible solute produced by soil, marine and freshwater bacteria in response to stressful factors. The purpose of our study was to determine the possible toxic influence of ECT on Daphnia magna. We determined the following endpoints: survival rate during exposure and recovery, swimming performance, heart rate, thoracic limb movement determined by image analysis, haemoglobin level by ELISA assay, catalase and nitric oxide species (NOx) by spectrophotometric methods. The results showed 80% survival of daphnids exposed to 50mg/L of ECT after 24h and 10% after 90h, however lower concentrations of ECT were well tolerated. A concentration-dependent reduction of swimming velocity was noted at 24 and 48h of the exposure. ECT (at 2.5 and 4mg/L) induced an increase of heart rate and thoracic limb movement (at 2.5, 4 and 20mg/L) after 24h. After 10h of the exposure to ECT daphnids showed a concentration-dependent increase of haemoglobin level synthesized and accumulated in the epipodite epithelia. After 24h we noted a concentration-dependent decrease of haemoglobin level and its lowest value was found after 48h of the exposure. ECT at a concentration of 20 and 25mg/L slightly stimulated catalase activity after 24h. NOx level was also increased after 10h of the exposure to 20 and 25mg/L of ECT reaching maximal activity after 24h. Our results suggest that ECT possesses some modulatory potential on the behaviour, physiology and biochemical parameters in daphnids.

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.

INFLUENCE OF PLANT COMPOSITION ON METHANE EMISION FROM MOSZNE PEATLAND

Methane is the second most important man-made greenhouse gas after carbon dioxide. For more than the last 20 years the increase of the rate of CH4 emission has been varying dramatically each year. This trend is common worldwide, though in different parts of the world unevenly intense, conditioned by the amount of emissions from natural and anthropogenic sources. Peatland ecosystems are one of the natural methane emitters, responsible for about 24% of the total CH4 emissions. Methane emission from wetlands is the balance between the processes of methanogenesis and methanotrophy with an active role of wetlands plants composition. Participation of vegetation in the reduction the emissions by 30-35% was confirmed. Association of methanotrophic bacteria with plants has been already recognized by Raghoebarsing and colleagues, who showed that methanotrophic bacteria, as endosymbionts and epibionts, live both inside and outside the cells of Sphagnum sp. The main aim of this study was to estimate methane emissions from Moszne peatland, dominated by: Sphagnum sp., Eriophorum vaginatum, Carex nigra and Vaccinium uliginosum.

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.

Biosynthesis of ectoine by the methanotrophic bacterial consortium isolated from Bogdanka coalmine (Poland)

Ectoine belongs to the family of compatible solutes, which are known to contribute mainly to the adaptation of the cell to osmotic stress by mediation of a constant turgor. In addition, the cell’s essential functions are maintained under difficult conditions like high salinity, heat, or aridity stress. Biosynthesis of ectoine has been found in halophilic and halotolerant microorganisms. We showed that the methanotrophic bacterial consortium (MBC) isolated from coalbed rocks from coalmine Bogdanka (Poland) and resistant to extreme environmental conditions (low content of moisture) was able to synthesize ectoine. MBC was cultured in mineral nitrate mineral salts medium supplied with NaCl at atmospheric air enriched with 10% of methane. The levels of methanotrophic activity were determined by the gas chromatography technique (943.05 ± 30.73 − 94.14 ± 0.85 μM CH4 gDW−1 day−1) and the biomass concentration of MBC was evaluated based on OD600, as well as biosynthesis of ectoine in relation to the salinity (0–5% NaCl) of the medium. The levels of ectoine tested by NIR measurements ranged from 1.33 ± 0.10 mg gDW−1 to 0.42 ± 0.08 mg gDW−1 depending on the salinity of the solution. In addition, we identified MBC based on the pmoA gene.

Cultivation and detection of endophytic aerobic methanotrophs isolated from Sphagnum species as a perspective for environmental biotechnology

Enriched cultures of microorganisms are an essential step in the production of inoculum of these organisms for biotechnology and bioengineering. The potential application of methanotrophic microorganisms for removal of methane produced from landfills and coal mines as well as biodegradation of toxic compounds has been widely studied. Therefore, searching for new sources of methanotrophs can contribute to increasing the possibilities of biotechnology and bioengineering.Enrichment cultures of endophytic methanotrophs from Sphagnum sp. were initiated in NMS medium, a most widely used medium for cultivation of methanotrophic bacteria from various environments proposed in 1970 by Whittenbury. Incubation was carried out at 10, 20, 30, and 37°C with vigorous shaking on a shaker (180 rpm). The source of carbon and energy for endophytes were methane at the concentration range between 1-20%.It appeared that the consortium of endophytic bacteria grew only at the temperature of 20 and 30°C. During the culture of endophytes, the measurements of gas concentration showed a steady loss of methane and oxygen, as well as accumulation of carbon dioxide as a CH4 oxidation product.The use of FISH has made characterization of endophytic consortia possible. It turned out that the population of endophytes consists of type I and II methanotrophs as well as associated non-methanotrophic bacteria.Furthermore, we determined the potential of the examined bacteria for methane oxidation, which ranged up to 4,7 μMCH4 per ml of the population of endophytes per day.

Methane Oxidation by Endophytic Bacteria Inhabiting Sphagnum sp. and Some Vascular Plants

Methane emission from wetlands is responsible for about 24% of the total CH4 emissions. The value of emission is a result of the balance between the processes of methane formation (methanogenesis) and sinks (methanotrophy). The methanotrophic activity from well-aerated soil surface layers has been relatively well recognized. On the contrary, the active role of plants in reduction of methane emission is rather not fully known. The association of methanotrophic bacteria with plants of Sphagnum spp., has already been recognized. In our investigations, particular attention was paid to vascular plants from a peatland overgrown by Sphagnum spp. but also Eriophorum vaginatum, Carex nigra, and Vaccinium oxycoccos. The gases emitted from the surface of Moszne peatland were collected using the chamber method from selected sites during growing seasons (spring, summer, autumn). To estimate the contribution of plants in methane emissions from the peatland, in each investigated site gas was sampled from the surface with the native flora cover and after removal thereof. Our results show that the reduction in the CH4 emission was related to the plant composition, vegetation period, and conditions of the plants. It was confirmed that the endophytes under investigation belonged to type I methanotrophs.