Silver nanoparticles (AgNPs) exhibit unusual biocidal properties thanks to which they find a wide range of applications in diverse fields of science and industry. Numerous research studies have been devoted to the bactericidal properties of AgNPs while less attention has been focused on their fungicidal activity. Our studies were therefore oriented toward determining the impact of AgNPs characterized by different physicochemical properties on Fusarium avenaceum and Fusarium equiseti. The main hypothesis assumed that the fungicidal properties of AgNPs characterized by comparable morphology can be shaped by stabilizing agent molecules adsorbed on nanoparticle surfaces. Two types of AgNPs were prepared by the reduction of silver ions with sodium borohydride (SB) in the presence of trisodium citrate (TC) or cysteamine hydrochloride (CH). Both types of AgNPs exhibited a quasi-spherical shape. Citrate-stabilized AgNPs (TCSB-AgNPs) of an average size of 15 ± 4 nm were negatively charged. Smaller (12 ± 4 nm), cysteamine-capped AgNPs (CHSB-AgNPs) were characterized by a positive surface charge and higher silver ion release profile. The phytopathogens were exposed to the AgNPs in three doses equal to 2.5, 5 and 10 mg L⁻¹ over 24 and 240 h. Additionally, the impact of silver ions delivered in the form of silver nitrate and the stabilizing agents of AgNPs on the fungi was also investigated. The response of phytopathogens to these treatments was evaluated by determining mycelial growth, sporulation and changes in the cell morphology. The results of our studies showed that CHSB-AgNPs, especially at a concentration of 10 mg L⁻¹, strongly limited the vegetative mycelium growth of both species for short and long treatment times. The cell imaging revealed that CHSB-AgNPs damaged the conidia membranes and penetrated into the cells, while TCSB-AgNPs were deposited on their surface. The fungistatic (lethal) effect was demonstrated only for silver ions at the highest concentration for the F. equiseti species in the 240 h treatment. The number of spores of both Fusarium species was significantly reduced independently of the type of silver compounds used. Generally, it was found that the positively charged CHSB-AgNPs were more fungicidal than negatively charged TCSB-AgNPs. Thereby, it was established that the stabilizing agents of AgNPs and surface charge play a crucial role in the shaping of their fungicidal properties.

The aim of the research was to evaluate the effect of three types of silver nanoparticles (AgNPs) with different physicochemical properties and silver ions delivered in the form of silver nitrate (AgNO₃) at the concentration of 50 mg L⁻¹ on germination and initial growth of monocots (common wheat, sorghum) and dicots (garden cress, white mustard). The AgNPs were prepared using trisodium citrate (TCSB-AgNPs), tannic acid (TA-AgNPs), and cysteamine hydrochloride (CHSB-AgNPs). They exhibited comparable shape, size distribution, and an average size equal to 15 ± 3 nm which was confirmed with the use of transmission electron microscopy. The electrokinetic characteristics revealed that CHSB-AgNPs have positive, whereas TCSB-AgNPs and TA-AgNPs negative surface charge. First, toxicity of the silver compounds was assessed using the Phytotestkit test. Next, after transferring seedlings to pots, shoot length, leaf surface, shoot dry mass, electrolyte leakage measurement, and photosystem II (PSII) efficiency were determined. AgNPs and silver ions delivered in the form of AgNO₃ reduced root and shoots length of common wheat, sorghum, and garden cress; leaves surface of garden cress and white mustard; and shoots dry mass of white mustard. The positively charged CHSB-AgNPs and silver ions delivered in the form of AgNO₃ showed the greatest inhibition effect. Moreover, silver ions and positively charged CHSB-AgNPs were more toxic to PSII of model plants than negatively charged TCSB-AgNPs and TA-AgNPs. AgNPs impact differed in the case of monocots and dicots, but the size of the changes was not significant, so it concerned individual parameters. The results revealed the interaction strength, which was generally similar in all tested plants, i.e., increasing negative effect in sequence TCSB-AgNPs < TA-AgNPs < silver ions delivered in the form of AgNO₃ < CHSB-AgNPs.

The aim of this study was to assess the changes in chemical and microbial properties and enzymatic activity of soil enriched with vermicompost derived from household waste. The vermicompost was tested in the rhizosphere of Larix decidua seedlings cultivated in 10-L pots in: (i) nursery soil (as the control), (ii) soil with 10% v/v vermicompost, and (iii) with 20% v/v vermicompost. The impact of vermicompost was assessed in terms of soil C/N ratio; bacterial, fungal, and nematode counts; and enzymatic activity. It was found that vermicompost increased the C/N ratio from 21 to 32, as well as the content of nitrate from 78 to 134 mg kg⁻¹, of ammonium from 14 to 139 mg kg⁻¹, of phosphorus from 92 to 521 mg kg⁻¹, and of potassium from 142 to 1912 mg kg⁻¹, compared with the control soil. The abundance of beneficial bacteria was increased (from 8.61 × 10⁷ to 37.9 × 10⁷), along with decreases in microbiological ratios of fungi and bacteria (e.g. fungi/Bacillus from 0.18818 to 0.00425). A significant 2- to 4-fold increase was observed compared with the control in the number of beneficial nematodes belonging to bacterivorous, fungivorous, and predatory groups with no change in the abundance of plant-parasitic nematodes. Addition of vermicompost brought about a change in soil enzyme activity. Vermicompost reduced the activity of alkaline phosphatase only. Both doses of vermicompost led to an increase in the activity of acid phosphatase, inorganic pyrophosphatase, dehydrogenases, β-glucosidase, and urease. Only the higher dose had an effect on increasing the activity of o-diphenol oxidase and proteases. No significant change was observed for nitrate reductase. Also, the presence of antibiotics produced by bacteria was detected depending on the dose of vermicompost, e.g. iturin (ituC) and bacillomycin (bmyB) were found in soil with a dose of 20% v/v vermicompost. Overall, vermicompost produced from household waste can be an excellent organic fertilizer for larch forest nurseries.

Bacteria isolated from bioaerosols emitted by a clarifier in a wastewater treatment plant (Dobre Miasto, Kosyń, Poland) were analyzed. A total of 27 morphologically different bacterial colonies were isolated, and 14 strains antagonistic towards Fusarium culmorum in vitro were selected for analysis. Most of the analyzed bacteria did not increase the germination capacity or the height of wheat seedlings. The only exception was strain PSDM20 which was characterized by multiple plant growth–promoting properties, but also by the lowest metabolic activity and lowest substrate assimilation. Strain PSDM16 deteriorated the status of wheat seedlings. Bacterial strains PSDM3, PSDM6, PSDM10, PSDM13, PSDM14, PSDM17, and PSDM20 prevented the deterioration of the biometric parameters of wheat seedlings exposed to F. culmorum and F. graminearum. Strains PSDM3, PSDM6, PSDM10, and PSDM17 most effectively protected wheat seedlings against infections caused by the above pathogens. Strain PSDM6 produced indole acetic acid (IAA), and it significantly contributed to plant elongation. Correlations were not observed between the growth-promoting properties, metabolic activity, and fungistatic properties of the evaluated bacteria. Pseudomonas putida PSDM3, Proteus penneri PSDM6, Enterobacter hormaechei PSDM10, and Advenella sp. PSDM17 were most effective in limiting the spread of Fusarium spp. infections in spring wheat, and they can be used as biological fungicides. The results of this study indicate that bacteria isolated from non-agricultural ecosystems are capable of protecting and fertilizing crops. The growth-promoting properties of bacterial strains of the genus Proteus are comparable with those of the widely investigated Pseudomonas spp. strains.