Selection, identification, and ecological application potential of key bacteria in biological soil crusts of deserts.

To address the challenges of nutrient deficiency and plant growth in desertified areas, we screened and identified key strains with extracellular hydrolase production and phosphorus and potassium solubilizing functions from biological soil crusts (BSC), and evaluated their survival capabilities under stressed conditions. Among the 13 strains screened from BSC, YD-7 exhibited the highest activity for amylase and cellulase, with hydrolysis zone diameters of 2.27 and 1.70 cm, respectively. YD-8 and YD-5 exhibited the highest activity for protease, with hydrolysis zone diameters of 2.79 and 2.15 cm, respectively. In the tests for phosphorus and potassium solubilizing abilities, strains YD-5, YD-7, and YD-8 showed high activity, with soluble phosphorus contents of 43.66, 37.23, and 35.61 mg·L^-1, respectively. Growth experiments under stress conditions indicated that these strains exhibited good growth characteristics (survival rate >50%) under conditions of PEG-6000 concentration below 10%, tempera-tures of 28-36 ℃, pH values of 4-9, and NaCl concentration below 3%. Analysis based on phylogenetic tree revealed that YD-5, YD-7, and YD-8 were identified as <i>Acinetobacter haemolyticus</i>, <i>Stenotrophomonas maltophilia</i>, and <i>Klebsiella pneumoniae</i>, respectively. All the three strains have the potential for improving the quality of desert soils.