Antagonistic activity of microorganisms against phytopathogens is mainly the results of plants’ health improvement due to the inhibition of pathogens growth and the induction of plants resistance against diseases. The aim of the research was to determine antagonistic properties of Pantoea agglomerans against Rhizoctonia solani. The properties of two strains P. agglomerans BC17 and BC45 were assessed according to the following criteria: mycelial growth of R. solani in the presence of bacterial metabolites, an impact of P. agglomerans on the growth of sugar beet in the pots containing soil with and addition of R. solani and without it, the ability to produce indole-3-acetic acid (IAA). It has been recorded that antagonistic properties of tested strains are different. In the presence of metabolites of BC17 strains, the mycelial growth of R. solani was inhibited by 78 % and for the strain BC45 the value amounted 46 %. In the pot bioassay the number of infested plants growing in the soil inoculated with P. agglomerans and the pathogen was lower when compared with the pots containing R solani. A higher reduction of infested plants, amounting 23 %, was obtained for the strain BC17. Both strains had the ability to produce IAA - a plant hormone of the auxin class, in the presence of tryptophan and its absence in the medium. The highest concentration of IAA was recorded after 7 days of culturing in the supernatant obtained from the media containing 2000 μg/cm³ of tryptophan. For the strain BC17 the concentration of IAA marked in the post - culturing liquid amounted 71.57 μg/cm³, and for the BC45 strain it amounted over 80 μg/cm³. Obtained results prove that P. agglomerans may be used in the biological protection against phytopatogenic strains of R. solani.

This paper presents the results of a twelve-month measurement campaign conducted at a rural single-family house in Poland. The external and internal filters of a recuperator used to mechanically ventilate the building were used to separate the total suspended particles (TSPs), and the concentrations of fifteen elements and abundance of fungi and bacteria were determined. Lower annual mean concentrations were observed indoors, and the concentrations of most elements did not significantly change between seasons. There were some differences between winter and summer, which may have resulted from changes in the ventilation regimes in the house. The number of bacteria was similar outdoors and indoors, while the amounts of fungi were higher indoors (p < 0.05). The order of metal concentrations outdoors agreed well with observations in other countries, while indoors the metal concentrations order indicated the individual characteristics of the building. The species diversity of fungi was higher than that of bacteria, and different species were found indoors and outdoors, while bacteria were typically present both indoors and outdoors. Different TSP sources were identified indoors and outdoors, suggesting limited penetration between the two environments. However, both environments were affected by traffic. Mechanical ventilation systems with built-in filters (such as recuperators) were useful in assessing the air quality within the building, and the changeable recuperation filters offer an approach to assess the air quality in several houses without any additional cost or discomfort to the residents.

Pleurotus ostreatus is one of the most widespread mushrooms in the world. It is a valuable and widely cultivated edible mushroom with nematicidal properties. The mycelium of this mushroom produces a toxin that paralyzes nematodes, after which the nematode becomes infected with the filament, resulting in its death. This feature can be put to practical use as a natural nematicidal agent. In this paper, we have described studies on two wild strains of P. ostreatus (PO1, PO2) and the monokaryotic progeny obtained from their fruiting bodies. Monokaryons were crossed with each other within the progeny of one strain (PO1xPO1; PO2xPO2) and of two different strains (PO2xPO1). The growth conditions, morphological and molecular characteristics, toxicity and ability to form hyphal knobs of the maternal strains, monokaryons and those obtained by crossing were studied. The toxicity of mycelium was tested against the model organism Caenorhabditis elegans. The results of the study allowed the selection of five progeny heterokaryotic mycelia with the best parameters useful for in-vitro control of nematodes.