Potassium-Solubilizing Activity of Bacillus aryabhattai SK1-7 and Its Growth-Promoting Effect on Populus alba L.

Abstract

In the present study, the potassium-solubilizing characteristics of Bacillus aryabhattai SK1-7 and its growth-promoting effect on plants were evaluated to determine the biotechnological potential of this bacterium in alleviating soil potassium deficiency. The potassium-solubilizing activity of SK1-7 was determined by fermentation. Additionally, the fermentation broth was determined by flame spectrophotometry. The aluminum and silicon ion contents in SK1-7 fermentation broth were determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) after digestion with nitric acid hydrogen peroxide hydrofluoric acid. Scanning electron microscopy (SEM)-based observations were performed to assess the morphological changes in potassium feldspar surfaces digested by potassium-solubilizing bacteria. In addition, the effects of SK1-7 on plant growth and soil physical and chemical properties were analyzed. After incubation for 7 days in a potassium-solubilizing medium, the concentration of potassium dissolved reached 10.8 μg/mL and the percentage of potassium released was 32.6%. The pH rapidly decreased from 7.2 to 4.321 within the first day and then further decreased to 3.90 after 7 days. After 7 days, the concentrations of aluminum and silicon in the fermentation broth were 1.01 and 24.19 μg/mL, respectively. The growth promotion assay results showed that SK1-7 has good growth-promoting effects on poplar and can effectively improve the available potassium content in poplar rhizosphere soil. The SK1-7 strain can effectively dissolve insoluble potassium to release soluble potassium ions and clearly promotes the growth of poplar after being applied to soil. Thus, the SK1-7 strain is a potassium-solubilizing microorganism with good application prospects.

The Contrivance of Plant Growth Promoting Microbes to Mitigate Climate Change Impact in Agriculture

“…The accumulation of osmoprotectants, electrically neutral, non-toxic and low molecular weight metabolites, reduces osmotic stress. Their effectiveness is based on supporting of turgor pressure in cells and ion transport across the plasma membrane [ 51 , 61 , 104 ]. Proline is a particularly important osmoprotectant for plants under drought conditions.…”

“…Fixing nitrogen from the atmosphere into organic forms allows plants to assimilate these compounds. Some of the PGPB can solubilize phosphate, potassium and zinc salts [ 104 , 116 , 117 , 118 , 119 , 120 ]. In addition, the activity of some PGPB leads to an increase in root surface area and root morphology, which improves nutrient uptake [ 121 ].…”

“…Abiotic stresses, as mentioned earlier, adversely impact on physical-chemical soil properties and microbial communities [ 23 , 103 , 135 ]. As a selection factor, long-term abiotic stress contributes to the evolution of specific microorganisms, able to survive in adverse environmental conditions [ 23 , 104 ]. Bacteria belonging to particular species differ in stress tolerance.…”

Psychrotolerant Mesorhizobium sp. Isolated from Temperate and Cold Desert Regions Solubilizes Potassium and Produces Multiple Plant Growth Promoting Metabolites

“…Only a small fraction of the K requirements of the plant is attained by direct contact through root interception, and the major fraction (90%) is held in insoluble forms [ 13 ]. The majority of the K required by plants must be transported in the soil to the roots [ 14 ], and the movement of K ions is a significant element in the supply of K. This transport happens mostly in soil fluid, the liquid phase of the soil, by mass flow (with the water going to the roots of a plant) and diffusion through the concentration gradient created by the absorbent surface, i.e., roots. Near the roots, the soil solution is rapidly exhausted of nutrients due to removal by the plants [ 15 , 16 ].…”

“…An array of such bacteria, such as Bacillus sp. [ 2 , 14 ], Pseudomonas sp. [ 25 ], Paenibacillus sp.…”