Browsing by Author "Bieganowski, Andrzej"

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    Differential responses of Type I and Type II methanotrophs to nonanoic (pelargonic) acid and glyphosate
    (Elsevier, 2026) Furtak, Adam; Bilokinna, Anna; Szafranek-Nakonieczna, Anna; Skrzypek, Tomasz; Zięba, Emil; Bieganowski, Andrzej; Pytlak, Anna
    Glyphosate (GLY) is the most widely used herbicide worldwide. However, in organic and conventional farming systems, a natural alternative — nonanoic (pelargonic) acid (PA) — is gaining importance. PA is a non-selective herbicide whose mode of action is through disruption of the cellular membranes. PA is also added to commercial glyphosate formulations as surfactant, thereby increasing the effectiveness of this herbicide. Through agricultural application, both compounds enter the soil environment, which serves as a habitat for methanotrophic bacteria (MB). Methane (CH4) contributes to approximately 20% of the greenhouse effect, and by limiting its net emissions from the environment, MB play a crucial role in mitigating global warming. Therefore, potential disruption of MB activity by herbicides is of great concern. This is the first study to examine the effects of PA, GLY, and their combinations on MB. We demonstrate the negative impact of field-relevant concentration of PA (but not GLY) on Methylomonas methanica and methanotrophic soil enrichment cultures (ECs) dominated by Type I (γ-proteobacteria). Type II (α-proteobacteria) MB were more resilient to PA exposure than Type I MB. The underlying mechanism of this differential response was the variable susceptibility of cellular membranes to disintegration by PA.
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    Signal molecules and enzymes produced by Rhizobium leguminosarum sv. trifolii strains originating from the subpolar and temperate climate zones as elements of adaptation to low temperature stress
    (Elsevier, 2025) Janczarek, Monika; Adamczyk, Paulina; Gałązka, Anna; Marzec-Grządziel, Anna; Wójcik, Magdalena; Polakowski, Cezary; Maciejczyk, Natalia; Bieganowski, Andrzej
    Rhizobium leguminosarum sv. trifolii is a soil bacterium capable of establishing a nitrogen-fixing symbiosis with Trifolium spp. (clover) plants. In this study, two subpopulations of Rlt strains derived from the subpolar and temperate climate zones were characterized with respect to different physiological and metabolic traits. In addition, the influence of temperature on these processes was examined. Our results indicated that all the rhizobial strains grew at pH 5–9, tolerated salinity, and were sensitive to a majority of antibiotics. Moreover, the subpolar strains proved to be more tolerant to salinity than the temperate strains. A great majority of the strains (83.8 %) produced acyl-homoserine lactones in a wide range of temperatures (10–25 ◦C). Although no difference in the frequency of this trait between the subpopulations was found, more highly efficient AHL-producers were found among the temperate strains. In terms of the production of iron-chelating compounds and phosphate solubilization, half of the studied Rlt strains exhibited these traits, but more effective isolates were identified within the temperate subpopulation. These rhizobia also synthesized high amounts of indole-3-acetic acid and exhibited ACC deaminase activity, which is important for the regulation of the plant hormone ethylene. Some differences in phenotypic profiles between the individual strains were observed. The temperature range of 20–25 ◦C was optimal, whereas lower temperatures negatively affected the production of these molecules. In addition, the Rlt population exhibited a large diversity with respect to the auxiliary genetic content and metabolic potential. In conclusion, the Rlt strains produced a large set of signal molecules and enzymes and utilized a variety of carbon, nitrogen, phosphorus, and sulfur sources, which ensures their successful adaptation to various environments.