Changes in the mycobiome structure in response to reduced nitrogen fertilization in two cropping systems of maize.

Nitrogen (N) is an essential element for plant productivity; hence, it is abundantly applied to the soil in the form of organic or chemical fertilizers, which consequently have a negative impact on the environment. Therefore, the main objective of our study was to investigate the structure and richness of the soil mycobiome in response to reduced nitrogen fertilization under two cropping systems: plowing (P) and no-till (NT). Moreover, the scope of the study perfectly falls into the EU "From Field to Table" strategy, which recommends a 20 % reduction of nitrogen fertilization of agricultural soils by 2030. In our study, the samples were collected twice during a single growing season: before maize sowing (without fertilization) and after harvesting the crop (four different fertilization rates). The mycobiome structure was identified based on the next generation sequencing (NGS) technique. Overall, our research has proved that the cropping system is important in terms of the formation of the fungal mycobiome structure and relative abundance. In addition, we confirmed that soil properties have a significant impact on fungal communities. We determined that a 20 % lower nitrogen fertilization rate (92.0 kg N ha-1) had a positive effect on the abundance of fungal communities. Moreover, the highest biodiversity at each of the taxonomic levels tested (phylum, class, genus) in the NT system and at the class and genus levels in the P system was also evidenced at the 20 % lower N fertilization rate. We also recommended potential indicators confirming the positive impact of reduced fertilization in two cropping systems: plowing - Epicoccum, Metarhizium, Mycosphaerella, and Paraconiothyrium and no-till - Peziza, Podospora, Metarhizium, Trechispora, and Umbelopsis.

Functional and Seasonal Changes in the Structure of Microbiome Inhabiting Bottom Sediments of a Pond Intended for Ecological King Carp Farming.

The main goal of the study was to determine changes in the bacterial structure in bottom sediments occurring over the seasons of the year and to estimate microbial metabolic activity. Bottom sediments were collected four times in the year (spring, summer, autumn, and winter) from 10 different measurement points in Cardinal Pond (Slesin, NW Poland). The Next-Generation Sequencing (MiSeq Illumina) and Community-Level Physiological Profiling techniques were used for identification of the bacterial diversity structure and bacterial metabolic and functional activities over the four seasons. It was evident that Proteobacteria, Acidobacteria, and Bacteroidetes were the dominant phyla, while representatives of Betaproteobacteria, Gammaproteobacteria, and Deltaproteobacteria predominated at the class level in the bottom sediments. An impact of the season on biodiversity and metabolic activity was revealed with the emphasis that the environmental conditions in summer modified the studied parameters most strongly. Carboxylic and acetic acids and carbohydrates were metabolized most frequently, whereas aerobic respiration I with the use of cytochrome C was the main pathway used by the microbiome of the studied bottom sediments.