Extremophilic bacteria as biofertilizer for agricultural wheat

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.