Effects of Exiguobacterium sp. DYS212, a Saline-Alkaline-Tolerant P-Solubilizing Bacterium, on Suaeda salsa Germination and Growth

Soil nutrient availability under saline-alkali stress limits plant primary productivity. P-solubilizing bacteria (PSB) improve inorganic P dissolution and promote plant growth. However, the application studies of saline-alkaline-tolerant PSB are still scarce. We isolated one PSB strain from bird droppings in saline-alkali regions and identified its growth characteristics and resistance to salt and alkali. A potting experiment with PSB addition was performed to analyze the effect of this strain on the germination and growth of Suaeda salsa. The PSB were identified as Exiguobacterium sp. DYS212 strain, and it utilized glucose, ammonium sulfate, and yeast extract powder well. The strain is halophilic, has the ability to dissolve inorganic P, and improved P-solubilization under 1–5.5% salinity (available P > 200 mg L−1), reached a maximum at 2.5% NaCl concentration yielding 410.73 mg L−1 of available P. The PSB promoted seed germination, especially under high alkaline stress, wherein the growth promoting rate increased to 5.26%. The PSB improved the growth of S. salsa, in terms of plant height, stem diameter, and biomass (up to 2.5 times), under saline and alkaline conditions. This study highlights the potential of Exiguobacterium sp. isolates as biofertilizers, and provides reference for environment sustainability of saline-alkali region.