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Wheat (Triticum L.) is a strategically important agricultural crop because its quality and yield provide food security for the population. Biological fertilizers improve the growth and development of agricultural crops. Unlike chemical ones, they have no toxic effect on people and the environment. This research assessed the positive effect of extremophilic microorganisms isolated from coal dump soils of the Kemerovo Region (Russia) on the growth and development of wheat. The study featured bacterial isolates of Achromobacter denitrificans, Klebsiella oxytoca, and Rhizobium radiobacter, as well as their consortia in four different ratios: 1:1:1 (Consortium A), 2:1:1 (Consortium B), 1:2:1 (Consortium C), 1:1:2 (Consortium D), respectively. The beneficial effect was assessed by determining such factors as nitrogen fixation, solubilization of phosphates, potassium, and zinc, and production of gibberellic acid, siderophores, and hydrogen cyanide. The wheat samples were checked for germination, root length, and stem length. R. radiobacter demonstrated the best nitrogen fixation properties. Consortium D, with two shares of R. radiobacter, yielded the best results for zinc solubilization. R. radiobacter proved to be the most efficient potassium solubilizer while the isolate of A. denitrificans was the best phosphate solubilizer. The largest amount of gibberellic acid belonged to K. oxytoca. Consortium C, which included two shares of this isolate, appeared to be the most effective siderophore producer. All samples but A. denitrificans were able to produce hydrogen cyanide. The best seed germination rate (84%) belonged to Consortium C, which contained a double share of K. oxytoca. Consortia C and B (two shares of A. denitrificans) had the greatest positive effect on the root length. Treatment with Consortium B resulted in the longest average stem length. Extremophilic microorganisms isolated from coal dump soils of the Kemerovo Region (Russia) had a good potential as biofertilizers that could improve wheat quality and local food security.

Abiotic and biotic stresses have a major impact on crop growth. Stress affects the root system and decreases the amount of nutrients in fruits. Modern agricultural technologies help replace mineral fertilizers with new generation biopreparation. Unlike chemical fertilizers, biofertilizers reduce the risk of adverse environmental impacts. Of special interest are extremophilic microorganisms able to survive in extreme conditions. We aimed to study the phytostimulating ability of extremophilic bacteria isolated from disturbed lands in the coal-mining region. We isolated microorganisms from disturbed lands and studied their cultural, morphological, and biochemical properties. Then, we determined their ability to synthesize indole-3-acetic acids. The extremophilic bacteria were identified and subjected to biocompatibility testing by co-cultivation. Next, we created consortia of pure cultures and analyzed biomass growth. Finally, the biopreparation was experimentally tested on Trifolium prantense L. seeds. We isolated 10 strains of microorganisms that synthesized 4.39 to 16.32 mg/mL of indole-3-acetic acid. The largest amounts of the acid were produced by Pantoea spp., Enterococcus faecium, Leclercia spp., Rothia endophytica, and Klebsiella oxytoca. A consortium of Pantoea spp., E. faecium, and R. endophytica at a ratio of 1:1:1 produced the largest amount of indole-3-acetic acid (15.59 mg/mL) and accumulated maximum biomass. The addition of 0.2% L-tryptophan to the nutrient medium increased the amount of indole-3-acetic acid to 18.45 mg/mL. When the T. prantense L. seeds were soaked in the biopreparation (consortium’s culture fluid) at a concentration of 2.5, the sprouts were 1.4 times longer on the 10th day of growth, compared to the control. The consortium of Pantoea spp., E. faecium, and R. endophytica (1:1:1) stimulated the growth of T. prantense L. seeds. Our findings can be further used to develop biofertilizers for agriculture.