Heavy-metal contaminants are one of the most relevant problems of contemporary agriculture. High toxicity and the ability to accumulate in soils and crops pose a serious threat to food security. To solve this problem, it is necessary to accelerate the pace of restoration of disturbed agricultural lands. Bioremediation is an effective treatment for agricultural soil pollution. It relies on the ability of microorganisms to remove pollutants. The purpose of this study is to create a consortium based on microorganisms isolated from technogenic sites for further development in the field of soil restoration in agriculture. In the study, promising strains that can remove heavy metals from experimental media were selected: Pantoea sp., Achromobacter denitrificans, Klebsiella oxytoca, Rhizobium radiobacter, and Pseudomonas fluorescens. On their basis, consortiums were compiled, which were investigated for the ability to remove heavy metals from nutrient media, as well as to produce phytohormones. The most effective was Consortium D, which included Achromobacter denitrificans, Klebsiella oxytoca, and Rhizobium radiobacter in a ratio of 1:1:2, respectively. The ability of this consortium to produce indole-3-acetic acid and indole-3-butyric acid was 18.03 μg/L and 2.02 μg/L, respectively; the absorption capacity for heavy metals from the experimental media was Cd (56.39 mg/L), Hg (58.03 mg/L), As (61.17 mg/L), Pb (91.13 mg/L), and Ni (98.22 mg/L). Consortium D has also been found to be effective in conditions of mixed heavy-metal contamination. Due to the fact that the further use of the consortium will be focused on the soil of agricultural land cleanup, its ability to intensify the process of phytoremediation has been studied. The combined use of Trifolium pratense L. and the developed consortium ensured the removal of about 32% Pb, 15% As, 13% Hg, 31% Ni, and 25% Cd from the soil. Further research will be aimed at developing a biological product to improve the efficiency of remediation of lands withdrawn from agricultural use.

Wheat is a vital agricultural crop whose phytopathogens include fungi of the genera Fusarium and Alternaria. Synthetic pesticides, which are used to combat them, have a negative impact on the environment. Therefore, there is a need for developing safe and effective biopesticides. We aimed to create a consortium of extremophilic microorganisms isolated from natural sources to protect wheat from the diseases caused by Alternaria and Fusarium fungi. Ten isolates of extremophilic microorganisms were tested for their antimicrobial activity against Escherichia coli and their antagonistic activity against phytopathogens. Based on the results, we developed microbial consortia and evaluated their effectiveness in protecting wheat from phytopathogens. Five of the strains under study showed the highest activity, three of which were biocompatible, namely Leclercia sp., Sphingomonas paucimobilis, and Lactobacillus plantarum. Four consortia were created from these microorganisms, of which consortium B (with a 2:1:1 ratio of the strains, respectively) proved the most effective. In particular, it increased the area free from the phytopathogen by 4.2% compared to the average values of its individual microorganisms. Also, the consortium had a phytostimulating effect on wheat seedlings (germination of 73.2–99.6%) and protected the seeds infected with phytopathogens from morphometric changes. The resulting consortium can be used as a biopesticide since it is highly effective in protecting wheat from Alternaria and Fusarium pathogens.

Intensifying agricultural production involves an active use of agrochemicals, which results in disrupted ecological balance and poor product quality. To address this issue, we need to introduce biologized science-intensive technologies. Bacteria belonging to the genera Azotobacter and Pseudomonas have complex growth-stimulating properties and therefore can be used as a bioproduct to increase plant productivity. We aimed to create a growth-stimulating consortium based on the strains of the genera Azotobacter and Pseudomonas, as well as to select optimal cultivation parameters that provide the best synergistic effect. We studied strains Azotobacter chroococcum B-4148, Azotobacter vinelandii B-932, and Pseudomonas chlororaphis subsp. aurantiaca B-548, which were obtained from the National Bioresource Center “All-Russian Collection of Industrial Microorganisms” of Kurchatov Institute. All the test strains solubilized phosphates and produced ACC deaminase. They synthesized 0.98–1.33 mg/mL of gibberellic acid and produced 37.95–49.55% of siderophores. Their nitrogen-fixing capacity ranged from 49.23 to 151.22 μg/mL. The strain had high antagonistic activity against phytopathogens. In particular, A. chroococcum B-4148 and A. vinelandii B-932 inhibited the growth of Fusarium graminearum, Bipolaris sorokiniana, and Erwinia rhapontici, while P. chlororaphis subsp. aurantiaca B-548 exhibited antagonism against F. graminearum and B. sorokiniana. Since all the test strains were biologically compatible, they were used to create several consortia. The greatest synergistic effect was achieved by Consortium No. 6 that contained the strains B-4148, B-932, and B-548 in a ratio of 1:3:1. The optimal nutrient medium for this consortium contained 25.0 g/L of Luria-Bertani medium, 8.0 g/L molasses, 0.1 g/L magnesium sulfate heptahydrate, and 0.01 g/L of aqueous manganese sulfate. The optimal cultivation temperature was 28°C. The microbial consortium created in our study has high potential for application in agricultural practice. Further research will focus on its effect on the growth and development of plants, in particular cereal crops, under in vitro conditions and in field experiments.

The biological fixation of atmospheric nitrogen by rhizobia plays a key role in the cycle of ecosystems and their productivity. In agriculture, it is often used to increase the yield of legumes. We aimed to assess the stimulatory properties of three bacterial strains (Ensifer meliloti 441 B-219, Ensifer mexicanus B-4064, and Rhizobium tropici B-216) and their potential for promoting wheat growth under laboratory conditions. The bacterial were obtained from the All-Russian Collection of Industrial Microorganisms (National Bioresource Center, Kurchatov Institute). To explore their potential for agronomic practices, we determined their stimulating properties and assessed antagonistic activity against such phytopathogens as Fusarium graminearum F-877, Bipolaris sorokiniana F-529, Botrytis cinerea F-1006, Erwinia rhapontici B-9292, and Xanthomonas campestris B-4102. Finally, we studied the effect of the strains on germination and the contents of photosynthetic pigments, nitrogen, and protein in the above-ground parts of wheat plants under laboratory conditions. All the test rhizobia strains demonstrated various stimulating properties. In particular, they produced phytohormones, fixed nitrogen, solubilized phosphates and zinc, and synthesized ACC deaminase. The strains also exhibited pronounced antagonistic activity against F. graminearum, B. sorokiniana, and Xanthomonas campestris. According to the laboratory tests, the wheat seeds treated with E. meliloti 441 B-219 and R. tropici B-216 had longer shoots and roots, as well as higher contents of chlorophyll and carotenoids in some wheat varieties. R. tropici also had a strong positive effect on the weight of shoots and roots in all wheat varieties. E. mexicanus B-4064 exhibited a positive effect only on germination in some varieties. However, none of the strains had a significant effect on the nitrogen content. The test rhizobia strains have significant potential for stimulating plant growth, but they do not contribute to a significant increase in nitrogen availability for wheat.

Ризобактерии для снижения биотического стресса яровой пшеницы (Triticum aestivum L.), вызванного фитопатогенными грибами