Browsing by Author "Nowak, Artur"

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    Effect of long-term radish (Raphanus sativus var. sativus) monoculture practice on physiological variability of microorganisms in cultivated soil
    (Elsevier, 2024) Nowak, Artur; Majewska, Małgorzata; Marzec-Grządziel, Anna; Ozimek, Ewa; Przybyś, Marcin; Słomka, Anna; Kutyrieva-Nowak, Nataliia; Gałązka, Anna; Jaroszuk-Ściseł, Jolanta
    Long-term monoculture may affect soil environment biodiversity. An example of such a plant is radish (Raphanus sativus var. sativus), an economically important crop in Poland, a quick-growing vegetable with intensified harvest throughout the season. The aim of this study was to determine changes in biodiversity of soil under radish cultivation and to compare the research methods applied. The monoculture practice affected soil pH, but the organic carbon content remained stable. 16S RNA-seq analysis revealed changes in soil microbial population, with the dominant phyla Proteobacteria (37.3%), Acidobacteria (19%), and Actinobacteria (16%), and the dominant taxa Gaiella (1.59%), Devosia (1.51%) and Nocardioides (1.43%). These changes have not fully expressed in the number of culturable microorganisms, where only fungal abundance changed significantly. However, the physiological state of microbial cells (λ) indicated that oligotrophs and copiotrophs were in a vegetative (λ > 3.0) state at the beginning of the season and fungi at the end of the year. Changes in the biodiversity of soil microorganisms were visualised using Community Level Physiological Profiling, where an oscillation in Average Well Colour Development (OD560 = 0.78–1.48) was observed in successive months of radish culture, with biodiversity indices (Shannon and Substance richness) remaining similar. The greatest variation in the influence of monoculture practice on soil factors was observed for the soil enzymes activities (for dehydrogenase and peroxidase activities – 0.5 μg TPF/h/g DW and 1.5 μmolPYGL/h/g DW respectively). Alkaline phosphatases predominated among this group of enzymes, and the activity of carbon metabolism enzymes decreased over the season, except for invertases, where an increase in activity of up to 50 μg Glc/h/g DW was observed. All the parameters studied indicated changes in the soil environment. Nevertheless the microbial community remains stable during the whole experiment returning to equilibrium in a quite short time after changing conditions.
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    Harnessing Indigenous Rhizosphere Bacteria to Improve Plant Growth and Soil Microbial Activity in the Cultivation of Lactuca sativa L. Under Drought Stress Conditions
    (Springer Nature, 2026) Woźniak, Małgorzata; Siebielec, Sylwia; Nowak, Artur; Siebielec, Grzegorz; Jaroszuk - Ściseł, Jolanta
    Purpose. The application of plant growth promoting rhizobacteria (PGPR) is considered to have the potential to improve plant development in water-stressed agroecosystems. The current study was designed to screen PGPR for a broad spectrum of functional traits that that can enhance plant growth and soil microbial activity under drought stress conditions. Methods. This study characterised selected indigenous bacterial strains isolated from the rhizosphere of Lactuca sativa, focusing on their ability to enhance nutrient bioavailability, phytostimulation and produce biofilms and exopolysaccharides. The isolates’ functional potential was validated under controlled conditions by evaluating plant biomass and soil enzymatic activity under two treatments: moderate drought stress and well-watered control. Results. Using the biological GEN III test, the strains tested were found to be metabolically diverse. Furthermore, the results indicate that all strains solubilize phosphate, fix nitrogen and synthesize indole-3-acetic acid (IAA) - like compounds. Most of them were active producers of siderophores and 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Out of 15 strains, 3 were strong biofilm producers, while all strains were extracellular polymeric substances (EPS) producers. The results of the pot experiment showed that decreasing irrigation significantly reduced the total biomass of lettuce by 36.2%. Lettuce plants inoculated with Bacillus spp. and Variovorax spp. strains exhibited a significant increase in dry weight, by 63.9% and 59.9%, respectively, under drought conditions compared to non-inoculated plants. Moreover, soils inoculated with the Bacillus spp. and Variovorax spp. strains showed higher dehydrogenase and phosphatase activities compared to the non-inoculated control; however, these differences were not statistically significant. Conclusions. Screening of the indigenous isolates revealed unique microbial traits with potential technological applications, including phosphate solubilization, biofilm and EPS production, nitrogen fixation, IAA synthesis, ACC deaminase activity, siderophore production, and high metabolic activity. Meanwhile, newly identified strains were found to enhance the development of butterhead lettuce under both optimal and reduced water availability.
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    Impact of Coal Waste Rock on Biological and Physicochemical Properties of Soils with Different Agricultural Uses
    (MDPI, 2025) Garbacz, Aleksandra; Nowak, Artur; Marzec-Grządziel, Anna; Przybyś, Marcin; Gałązka, Anna; Jaroszuk-Ściseł, Jolanta; Grzywaczewski, Grzegorz
    During the mining process in mines, a problem arises with the formation of coal post-mining waste, which is waste rock. It is often stored by mines on various types of land to manage the resulting spoil. However, this is not without its impact on the soil. In this study, we determined the biological and physicochemical properties of rhizosphere soils of the podzolic type, subjected to waste rock reclamation and without the influence of waste rock (control), differing in the type of agricultural use and type of plant cover: field-monocotyledonous (oat cultivation), field-dicotyledonous (buckwheat cultivation), and wasteland covered with very species-poor vegetation. Research has shown that long-term cultivation (buckwheat) contributed to the elimination (leveling out) of the microbial and biochemical differences. The addition of waste rock significantly reduced the number of microorganisms synthesizing siderophore, especially on wasteland (decreased by 1.5 log10/gDW). The abundant presence of the genera Acidocella and Acidphilum, absent in wasteland without waste rock, in the unused soil under the influence of waste rock was strongly associated with the effect of lowering the pH by waste rock in soil not used for agriculture. Increased levels of 77 types of bacteria were observed in samples from buckwheat cultivation compared to wasteland. The number of microorganisms resistant to heavy metals as well as microorganisms capable of producing specific Fe-binding ligands—siderophores—decreased under the influence of waste rock. Moreover, the dehydrogenase activity in long-term cultivation both under the influence of waste rock and without its influence was at a similar level. In contrast, an almost 100-fold decrease in dehydrogenase activity was observed in soils with oat cultivation and a more than 4-fold decrease in acid phosphatase (ACP) and alkaline phosphatase (ALP) activity. These parameters provide an effective system for monitoring soil health, from inexpensive and fast methods to advanced and precise techniques. The results can be applied to solve the problems associated with coal mining wastes by developing methods for their use in soils with long-term agricultural use.
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    Plant growth promotion mechanisms of bacteria isolated from a long-term reclaimed smelter waste deposit
    (Springer Nature, 2025-09-29) Sylwia, Siebielec; Woźniak, Małgorzata Martyna; Nowak, Artur; Siebielec, Grzegorz; Kozieł, Monika; Sugier, Piotr; Jaroszuk-Ściseł, Jolanta
    The use of beneficial bacterial strains is proposed as a nature based practice to support sustainable crop production. Strains exposed to extreme environmental stress may have developed robust stress resistance and the capacity to enhance plant growth under unfavorable conditions. Our study provides the new aspect in characterising bacteria from polluted soil. The novelty of our study was isolation of bacteria from a long-term contaminated site and their testing for plant growth promoting mechanisms. The aim of this research was to characterize bacterial strains, collected from the root zone of grasses growing in a heavily polluted smelter wasteland reclaimed 25 years ago using sewage sludge and by-product lime. Their capability to enhance plant resistance to stresses has not been widely assessed. The activity of the strains was assessed based on mechanisms associated with nutrient uptake: phosphate solubilization, ability to fix atmospheric nitrogen (N), ability to synthesize indole-3-acetic acid (IAA)-like compounds, and mechanisms linked to plant stress tolerance: ACC deaminase production, polysaccharides and biofilm development. Metabolic profiling of the strains was performed. Most strains tested in this study exhibited a range of plant growth promotion mechanisms. All strains solubilized phosphates with medium to high intensity, 14 of 15 isolates produced IAA up to 60 μg/mL, all fixed N from 15.85 to 50.00 mg/ml after 72 h. Thirteen strains survived freeze-drying. Our study enabled clustering bacterial strains with capability to perform certain groups of processes. Strains intensively fixing N in general were also able to intensively produce IAA but rather were not efficient producers of extracellular polymeric substances (EPS). IAA production was negatively correlated with 1-aminocyclopropane-1-carboxylic acid deaminase (ACC) deaminase activity and average carbon utilization intensity. All three strains selected for the pot study (Burkholderia sp., Pseudomonas caspiana, and Phyllobacterium sp.) confirmed the effectiveness in promoting wheat growth both at optimal and low soil moisture. The study shows that 25-years reclaimed smelter wastelands are reservoirs of PGPR strains potentially useful for developing biofertilizers enhancing plant growth and resistance to environmental or climatic stresses in agriculture.