Anna Pytlak

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.

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.

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.