Abstract Selenium (Se) is an essential yet globally scarce element, and microbial vectors offer an innovative method for augmenting Se bioavailability in crops. Trichoderma harzianum DEMf 1V and Тrichoderma citrinoviride DEMf: TR3 were grown in nutrient media with 2.5 and 5 mg Se l−1 to obtain Se-enriched biomasses. T. harzianum DEMf 1V accumulated the highest Se amount, 1262.50 µg g−1 DW. In a pot experiment, Se-enriched T. harzianum DEMf 1V used as a wheat biofertilizer, induced a 70% higher Se content than seedlings fertilized with Na₂SeO₃. The results verified the growth-promoting effects of T. harzianum DEMf 1V and Se-enriched T. harzianum DEMf 1V, whose application caused higher biomass production (47 and 55%, respectively) and chlorophyll content (23 and 42%, respectively) compared with the control. Fungal biochemical characteristics confirmed Se as a factor that modulates enzymatic profiles and volatile organic compounds production and stimulates auxin production, suggesting a potential synergistic interaction between Se enrichment and plant growth-promoting mechanisms. The presented results demonstrated that Se enrichment of T. harzianum produced a multifunctional biofertilizer that represents a source of Se and a potent tool for amplifying the plant growth-promoting effects of Trichoderma spp.

AbstractSelenium (Se) is an essential yet globally scarce element, and microbial vectors offer an innovative method for augmenting Se bioavailability in crops. Trichoderma harzianum DEMf 1V and Тrichoderma citrinoviride DEMf: TR3 were grown in nutrient media with 2.5 and 5 mg Se l−1 to obtain Se-enriched biomasses. T. harzianum DEMf 1V accumulated the highest Se amount, 1262.50 µg g−1 DW. In a pot experiment, Se-enriched T. harzianum DEMf 1V used as a wheat biofertilizer, induced a 70% higher Se content than seedlings fertilized with Na₂SeO₃. The results verified the growth-promoting effects of T. harzianum DEMf 1V and Se-enriched T. harzianum DEMf 1V, whose application caused higher biomass production (47 and 55%, respectively) and chlorophyll content (23 and 42%, respectively) compared with the control. Fungal biochemical characteristics confirmed Se as a factor that modulates enzymatic profiles and volatile organic compounds production and stimulates auxin production, suggesting a potential synergistic interaction between Se enrichment and plant growth-promoting mechanisms. The presented results demonstrated that Se enrichment of T. harzianum produced a multifunctional biofertilizer that represents a source of Se and a potent tool for amplifying the plant growth-promoting effects of Trichoderma spp.

Trichoderma harzianum DEMf 1V and Тrichoderma citrinoviride DEMf: TR3 are confirmed biocontrol agents used in this study to estimate the effects of selenium enrichment on their antifungal activity. Se-enriched cultures were prepared by growing on potato-dextrose broth supplemented with 2.5 and 5 mg Se/L added in the form of Na2SeO3. The antifungal activity of Se-enriched and control cultures was estimated by their ability to produce hydrolytic enzymes, which were detected using API ZYM, cellulase and protease tests. The antagonistic potential and impact of volatile compounds were observed in interactions with Botrytis cinerea, Fusarium oxysporum, and Fusarium graminearum. In Se-enriched T. harzianum DEMf 1V, the production of esterase, lipase, and N-acetyl-β-glucosaminidase was inhibited, while in Se-enriched Т. citrinoviride DEMf: TR3, only lipase production was interrupted. All cultures maintained the ability to produce cellulase and protease. Cultures of T. harzianum DEMf 1V grown with and without Se enrichment exhibited a high inhibition rate against B. cinerea (68–74%) and F. oxysporum (62–70%). The antagonistic activity of Se-enriched T. harzianum DEMf 1V against F. graminearum (65–66%) was higher compared to the control (60%). Se-enriched Т. citrinoviride DEMf: TR3 expressed lower inhibition against B. cinerea and F. graminearum compared to the control. Volatile compounds caused a low level of inhibition, indicating that they are among the antifungal mechanisms employed by the isolates, but not the dominant one. Further research should be directed towards the precise determination of metabolic changes induced by Se enrichment and the implications thereof for Trichoderma's antagonistic activities.

Sewage sludge (SS) is a nutrient-rich byproduct of wastewater treatment that presents both management challenges and valuable potential for agriculture. Direct land application of raw SS is the most cost-effective disposal approach; nonetheless, this method is restricted due to heavy metals, pathogens, and other contaminants. Composting has emerged as a sustainable strategy for stabilizing SS, enhancing its agronomic value, and ensuring compliance with environmental and regulatory standards. This review explores the physicochemical and microbiological properties of SS and the process of turning it into high-quality compost for applications as a soil amendment or nutrient supplement.

Antibiotics are significant microbial compounds that are commonly utilized to treat bacterial illnesses. Their use began in the early twentieth century, and there have been numerous antibiotics created worldwide since then. Antibiotics saved millions of lives and increased plant productivity because of their benefits in human and animal medicine and plant agriculture. However, its broad use has had major environmental repercussions, including buildup in agricultural ecosystems and the food chain, as well as wastewater and sewage sludge. Antibiotics are overused in animal agriculture and the veterinary sector in comparison to human use, and this overuse is linked to antibiotics leaching into the environment via feces and urine, posing a high risk of antibiotic contamination in manure and the transmission of antibiotic-resistant genes. The accumulation of antibiotics resulted in the creation of antibiotic-resistant bacteria, which entered the food chain. The majority of them are human pathogenic bacteria from a variety of genera, including Escherichia, Salmonella, Shigella, Listeria, and Campylobacter. These bacteria have antibiotic resistance genes and can cause serious health issues in humans. Antibiotics, such as tetracyclines, β-lactams, quinolones, macrolides, and sulfonamide, have been found in activated sludge, raw sewage, digested sludge, and treated effluents. Conventional wastewater treatment plants are not equipped to remove them. According to the literature, some bacteria found in agricultural ecosystems, food chains, and effluents may be multidrug resistant, which could have major ramifications for human health. This report summarizes the hazards and implications of antibiotic use and the occurrence of antibiotic-resistant microorganisms in the environment.

The growing demand to reduce the use of agrochemicals in all stages of food production underlines the need for eco-friendly and safe substitutes to insecticides. Despite the potential, microorganisms and their metabolites are still neglected among alternative pest control strategies. In the study, for the first time the impact of Bacillus amyloliquefaciens D5 ARV, B. siamensis 32DfEM, Azotobacter chroococcum F8/2, and Pseudomonas putida P1 ARV on Tribolium castaneum (Herbst, 1797) (Coleoptera: Tenebrionidae) mortality and behaviour was examined. The insecticidal effect was tested by adding cell or spore suspension to 1 g of wheat bran. API ZYM tests determined bacterial enzymatic profiles and completed with the tests for cellulases and chitinases production. A two-arm olfactometer tested the repellent effect. Volatile metabolites were detected by GC-MS analysis. B. amyloliquefaciens, A. chroococcum and B. siamensis caused 6.67 %, 10 % and 50 % mortality. All four soil bacteria showed a strong repellency for T. castaneum (p < 0.01) and the strongest was expressed by B. siamensis 32DfEM (p = 0.00009) which volatile blend consisted of 2,5-Dimethylpyrazine and 2-ethyl-6-methyl-pyrazine. Depending on the bacterial species, insects spent from 69 to 58 % of the total time in the control arm compared to the arm with bacterial volatiles (31-16 %). This represents a novel investigation in this field and demonstrates the significant repellent efficacy of soil bacteria, which could be utilized to control T. castaneum and other storage pests in an eco-safe and chemical-free approach.

Integrated pathogen management incorporates biological control and ecological services of plant growth-promoting bacteria as base components. The biocontrol activity of Bacillus amyloliquefaciens D5 ARV toward Fusarium oxysporum, Fusarium graminearum, Botrytis cinerea, and Macrophomina sp. was estimated through a confrontation test, and the potential of volatile and non-volatile organic compounds (VOCs). The results of the confrontation test showed 60, 46, 37, and 33% of F. oxysporum, F. graminearum, B. cinerea, and Macrophomina sp. growth inhibition, while VOCs effects reached 30%, 47%, 53%, and 0% growth inhibition, respectively. A collection of non-volatile metabolites was made at a stationary phase; afterward, they were sterilized by filtration or autoclaving. Autoclaving caused a significant loss of non-volatile metabolite antifungal activity. GC-MS analysis of VOCs detected the presence of compounds with antifungal and antimicrobial properties such as pentadecanoic acid, and hexanedioic acid, bis(2-ethylhexyl) ester. The multiple antifungal mechanisms revealed in this study are part of the B. amyloliquefaciens D5 ARV arsenal and make it a potentially powerful biocontrol agent against selected phytopathogens.

Microbial degradation, compared with many other degradation processes, is the most important pathway for the depletion of triazine herbicides in soil. The aim of this study was to determine the growth potential of Pseudomonas sp. CY in the presence of atrazine and additional carbon (sodium citrate) and nitrogen (ammonium-nitrate) sources. The experiment was performed with five treatments: i) 100 mg/L atrazine (control); ii) One hundred mg/L atrazine + sodium citrate (0.3 %, w/v); iii) One hundred mg/L atrazine + sodium citrate (0.3 %, w/v) + ammonium nitrate (0.6 %, w/v); iv) Atrazine (300 mg/L) + sodium citrate (0.3 %, w/v) and v) Atrazine (500 mg/L) + sodium citrate (0.3 %, w/v). The bacterial count was determined after incubation (7 days at 30°C) using the agar plate method, while atrazine degradation was determined by measuring the optical density at 221 nm. Pseudomonas sp. CY can partially utilize atrazine as the sole source of carbon and energy. The highest values of the bacterial count were determined at the highest initial atrazine concentrations; however, bacterial growth was not detected in these treatments. A significant impact of citrate on bacterial growth and atrazine degradation was observed, while the addition of nitrate decreased the atrazine degradation rate. This study confirmed that Pseudomonas sp. CY can be used as a prominent candidate for the remediation of atrazine-affected environments.

This study assesses the effects of Azotobacter biopriming on the early development of sugar beet. Azotobacter chroococcum F8/2 was screened for plant growth promoting characteristics and biopriming effects were estimated through germination parameters and the structural changes of the root tissues. A. chroococcum F8/2 was characterized as a contributor to nitrogen, iron, and potassium availability, as well as a producer of auxin and 1-aminocyclopropane-1-carboxilic acid deaminase. Applied biopriming had reduced mean germination time by 34.44% and increased vigor I by 90.99% compared to control. Volatile blend comprised 47.67% ethanol, 32.01% 2-methyl-propanol, 17.32% 3-methyl-1-butanol, and a trace of 2,3-butanedione. Root micromorphological analysis of bioprimed sugar beet revealed a considerable increase in primary, secondary xylem area, and vessels size. Obtained results determine A. chroococcum F8/2 as a successful biopriming agent, and active participant in nutrient availability and hormonal status modulation affecting root vascular tissue.

A large number of soil microorganisms arc characterized as plant growth promoting, but there seems to be a lack of comprehensive knowledge regarding plant growth promoting soil yeasts. The aim of the experiment was to analyse the properties of three yeast species: Schwanniomyces occidentalis BK0302D, Cyberlindnera saturnus CK2404I and Candida tropicalis 2TD2912B, important for plant growth (ammonium sulphate transformation, phosphorus, potassium and zinc dissolution), and to evaluate the effect of yeast on the growth of common wheat and white mustard seedlings after seeds' inoculation. Common wheat and white mustard seeds were inoculated with the selected yeasts. The final measurements showed that the highest amount of nitrate (10.40 mu g mL(-1) NO3-) was produced by C. saturnus CK24041, while S. occidentalis BK0302D solubilized the largest amount of phosphorus (63.70 mu g mL(-1) P). All three strains are marked as potassium and zinc solubilizers with both acid and alkaline phosphatase activity. This is the first report on S. occidentalis and C. tropicalis ability to solubilize insoluble potassium and zinc, and C. saturnus ability to solubilize insoluble phosphorus, potassium and zinc. Also, C. tropicalis 2TD2912B exhibited high antagonistic activity (66% growth inhibition) toward Botrytis cinerea. In vivo trial was conducted in a low-nutrient substrate, and S. occidentalis BK0302D was found to have the most considerable influence on common wheat biomass production (34% increase). White mustard inoculation with C. saturnus CK24041 resulted in a 4-fold higher biomass production, while S. occidentalis BK0302D induced a 2-fold increase. The presented results confirmed the multi-functional plant growth promoting characteristics of the tested yeasts and their potential for broad application from conventional agriculture on low-nutrient soils to revegetation of disturbed substrates.

Agricultural production has benefited a lot from herbicides; however, the use of herbicides caused many environmental problems. Herbicide application can affect the biodiversity of an ecosystem by killing non-target organisms. Microorganisms in the soil are important factors for plant growth; they represent the biological factor of soil fertility. Herbicides can have a beneficial effect on the development of some microorganisms and a negative on others, leading to depletion of microbial diversity in soil. The objective of this work is to determine microbial activity in the soil and to isolate herbicide-resistant bacteria after the use of the "Stomp" herbicide. Agar plate method was used for the determination of microbial prevalence in the soil. The results showed an increase in the total number of bacteria, ammonifiers, fungi, and actinomycetes. Nine isolates, mostly Gram-positive spore-forming rods, showed an ability to grow in the mineral salt medium with different concentrations of "Stomp" herbicide. Isolates G1/1 and G1/2, showed high level of tolerance at the initial pendimethalin concentration of 25 mg/l. Those isolates have the potential to be used to decontaminate herbicide affected ecosystems.

Different priming methods were developed to improve seed germination and the early growth of seedlings. This study aimed to examine the combined effect of bacterial inoculation and static magnetic field on white mustard (Sinapis alba L.) germination. A plant growth-promoting bacterial strain Bacillus amyloliquefaciens D5 ARV was used for biopriming. The static magnetic field of 90 mT was applied for 5 and 15 min. Analyses of abscisic acid, chlorophyll, anthocyanins, flavonoids content, nitrogen balance index, and bacterial indole-3-acetic acid were used to explain observed effects. Bacterial inoculation improved seed germination, whereas exposure to 90 mT for 15 min suppressed germination. Such an unfavorable effect was neutralized when the treatment with the static magnetic field was combined with bacterial inoculation. The highest germination percentage was a result of synergistic action of B. amyloliquefaciens D5 ARV and 15 min long exposure to 90 mT, which induced an increase of 53.20% in the number of germinated seeds. The static magnetic field induced the increase of bacterial indole-3-acetic acid production threefold times. Biomagnetic priming caused a metabolic shift from primary to secondary metabolism in the white mustard seedlings. An adequate combination of biological priming and static magnetic field treatment can be successfully used in old seed revitalization and germination improvements. © 2021 Bioelectromagnetics Society.

The improvement of wastewater treatment techniques is of crucial importance for effluent quality, but it also results in an increased amount of waste sludge. Dehydrated sludge contains organic matter and nutrients, and therefore it can be used in agriculture and bioremediation, but it is considered a potential source of environmental pollution. As the sludge analyzed in the research does not contain impermissible levels of organic and inorganic pollutants, the aim of the research was to examine microbiological, particularly sanitary, aspects and potential for its further use. Microbial diversity was determined by the standard serial dilution technique and selective media, and sanitary quality indicators (total coliforms, fecal coliforms, Escherichia coli and Salmonella spp.) were determined by the MPN method. The abundance of fungi, actinomycetes, and bacteria (ammonifiers, spore-forming bacteria and Pseudomonas spp.) indicate possibilities for further use of the sludge. The chemical analysis included the following parameters: total nitrogen (N), phosphorus in the form of P2O5 (available P), organic carbon (C), C/N ratio, pH, and water content. The chemical composition indicates the potential of sewage sludge to be used as a soil fertilizer, but its C/N ratio is not adequate to enable successful conversion to biosolids by the composting process. The obtained results indicate a significant level of microbiological contamination, which was most pronounced in the centre of the stabilized sludge pile. The research showed the necessity to conduct further studies on the microbial diversity and sanitary aspects of sewage sludge for proper waste sludge management.

Pinus sylvestris bark represents a rich source of active compounds with antifungal, antibacterial, and antioxidant properties. The current study aimed to evaluate the antifungal potential of P. sylvestris bark against Botryosphaeria dothidea, Dothiorella sarmentorum, and Neofusicoccum parvum (Botryosphaeriaceae) through its chemical (water extracts) and biological (Trichoderma spp. isolated from the bark) components. The water bark extracts were prepared at two temperatures (80 and 120 °C) and pH regimes (7 and 9). The presence of bark extracts (30%) caused inhibition of mycelial growth of B. dothidea and D. sarmentorum for 39 to 44% and 53 to 60%, respectively. Moreover, we studied the antagonistic effect of three Trichoderma isolates originating from the pine bark. Trichoderma spp. reduced growth of B. dothidea by 67%–85%, D. sarmentorum by 63%–75% and N. parvum by 55%–62%. Microscopic examination confirmed typical mycoparasitism manifestations (coiling, parallel growth, hook-like structures). The isolates produced cellulase, β-glucosidase and N-acetyl-β-glucosaminidase. The volatile blend detected the emission of several volatile compounds with antimicrobial activity, including nonanoic acid, cubenene, cis-α-bergamotene, hexanedioic acid, and verticillol. The present study confirmed in vitro potential of P. sylvestris bark extracts and Trichoderma spp. against the Botryosphaeriaceae. The study is an important step towards the use of environmentally friendly methods of Botryosphaeriaceae disease control.

Red clover (Trifolium pratense L.) seeds were inoculated with several plant growth-promoting bacteria (PGPB) and sown in the substrate contaminated with polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organometallic derivatives of tin (OT). The aim was to determine if selected PGPB strains can promote the growth of red clover in the substrate contaminated with several organic pollutants. The influence of bacteria on red clover growth (height, root length and biomass) was monitored during the three-month experimental period. The most significant improvements of seedling height were noted in the treatment with Bacillus amyloliquefaciens D5 ARV and Pseudomonas putida P1 ARV. Root growth was positively affected by Serratia liquefaciens Z-I ARV. The same isolates significantly affected biomass production. Those isolates caused total biomass increases of 70%, 48% and 33% compared to control. Bacterial strains used in this study were already confirmed as PGPB by biochemical testing, as well as by an in vivo test of mixed inoculums on several woody plants grown in the coal-mine overburden site. This work is the first-time record on their individual effects on one plant species. Obtained results confirmed that inoculation with several PGPB strains can enhance red clover growth in polluted soil.

Botryosphaeriales represent a diverse order of fungal pathogens of various woody plant species. In Serbia, these fungi are important pathogens of forest, ornamental, and fruit trees causing die-back, cankers, leaf blights, fruit, and root rot. The aim of this study was to evaluate the antifungal activity of Pinus sylvestris bark extracts and Trichoderma spp. against Botryosphaeria dothidea, Dothiorella sarmentorum, and Neofusicoccum parvum (Ascomycota, Botryosphaeriales) isolated from Picea abies, Thuja occidentalis, and Prunus laurocerasus trees planted in urban areas in Serbia. Bark extracts were prepared in water solution at two temperatures (80 and 120 °C). The extracts were tested using two concentrations (20% and 30%). Moreover, two Trichoderma isolates obtained from P. sylvestris bark were tested against Botryosphaeriales and their antagonistic potential was estimated in vitro using a confrontation test. Mycelial growth of B. dothidea and D. sarmentorum was significantly inhibited in the presence of bark extracts, while N. parvum showed no growth inhibition. Botryosphaeria dothidea growth was inhibited by 35 to 39% in the case of 20% extracts and by 39 to 44% in the case of 30% extracts. The growth inhibition of D. sarmentorum was between 48% and 56% in the case of 20% extracts and between 53% and 60% in the case of 30% extracts. The two Trichoderma isolates showed antifungal activity against the selected pathogens. An isolate BKG 4 showed the highest inhibition level, and it inhibited the growth of B. dothidea, D. sarmentorum, and N. parvum by 85%, 75%, and 62%, respectively. Preliminary results suggest that both P. sylvestris bark extracts and Trichoderma spp. could be used as biocontrol agents against B. dothidea, D. sarmentorum, and N. parvum, and this should be a further studied.

Zeolites can mitigate ammonium losses to the environment by taking up the ions from sources such as farmyard manure and ammonium-bearing fertilizers. This ability can improve nitrogen fertilizing practice given that ammonium ions loaded onto zeolite are available for plant uptake. The main goal of this study was to assess the influence of zeolite (clinoptilolite) and ammonia-loaded clinoptilolite on growth and yield of red clover (Trifolium pratense L.), as well as their influence on the microbial dynamics in soil. Plants sown in pots were cut four times, and dry matter yield (DM) of each harvest was weighed. The number of culturable bacteria, moulds, ammonifiers, Azotobacter sp. and actinomycetes was determined at the beginning of the experiment, and after each harvest. Two control treatments (soil without fertilizer and soil supplemented with mineral fertilizer - CAN) were included in the study. The application of ammonia-loaded clinoptilolite positively and significantly affected the microbial activity and provided higher yields (from 4.9 g/pot in ammonia-loaded clinoptilolite treatment to 4.3 g/pot in soil with zeolite treatment). Our results suggest that the addition of clinoptilolite to organic fertilizers (manure, composts) could be recommended. The increase of microbial communities’ abundances and their activity represented the key benefit from clinoptilolite application.

Overburden waste dumps represent a huge threat to environmental quality. The reduction of their negative impact can be achieved by vegetation cover establishment. Usually, this action is complicated due to site-specific characteristics, such as nutrient deficiency, elevated metal concentration, low pH value, lack of moisture and lack of organic matter. Establishment of vegetation can be facilitated by inoculation with plant growth promoting bacteria (PGPB) which improve the physicochemical and biological properties of degraded substrates and make them more hospitable for plants. In this study we selected several strains based on the ability to produce ammonia, indole-3-acetic acid, siderophores and lytic enzymes, and to solubilize inorganic phosphates. This selection resulted in microbial consortia consisting of Serratia liquefaciens Z-I ARV, Ensifer adhaerens 10_ ARV, Bacillus amyloliquefaciens D5 ARV and Pseudomonas putida P1 ARV. The effects of PGPB consortia on one-year-old London plane (Platanus × acerifolia [Aiton] Willd.) seedlings replanted into overburden waste from Kolubara Mine Basin were examined. After seven months, inoculated seedlings were 32% higher with 45% wider root collar diameter and over 80% higher total dry biomass compared to uninoculated seedlings grown in Kolubara’s overburden. Inoculation resulted in higher amounts of total soluble proteins, higher chlorophyll and epidermal flavonoids content and higher total antioxidative capacity in the leaves. This study represents a successful search for effective PGPB strains and shows that microbial consortia have an important role in enhancing the growth of seedlings in nutrient deficient and degraded substrates such as overburden waste from open-pit coal mines. Positive response of London plane seedlings suggest that inoculation may help widening the opus of species for reforestation of post mining areas and speed up natural succession processes and recovery of degraded landscapes.

Modern, efficient, and cost-effective approach to remediation of heavy metal-contaminated soil is based on the application of microorganisms. In this paper, four isolates from agricultural and urban contaminated soil showed abundant growth in the presence of copper(II) sulfate pentahydrate (CuSO4·5H2O) up to 2 mM. Selected yeasts were identified by molecular methods as Candida tropicalis (three isolates) and Schwanniomyces occidentalis (one isolate). C. tropicalis (4TD1101S) showed the highest percentage of bioaccumulation capabilities (94.37%), determined by the inductively coupled plasma optical emission spectrometry (ICP-OES). The Raman spectra of C. tropicalis (4TD1101S) analyzed in a medium with the addition of 2 mM CuSO4·5H2O showed certain increase in metallothionein production, which represents a specific response of the yeast species to the stress conditions. These results indicate that soil yeasts represent a potential for practical application in the bioremediation of contaminated environments.