Phosphate-solubilizing characteristics of yeasts

Phosphorus (P) is an essential element for plant development and metabolism. Because of its low availability and mobility in soils, it is often a limiting nutrient of plant growth. When phosphorus content in soil is insufficient, symptoms of phosphorus deficiency can appear, such as purple spots on leaves and stems or inhibition of development and maturation. To provide adequate nutrients for plant growth, appropriate fertilizers should be applied. However, overuse of chemical fertilizers can cause unanticipated environmental effects. To decrease the negative environmental effects resulting from continued use of chemical fertilizers, we can inoculate plants with phosphate-solubilizing microorganisms. Phosphate-solubilizing microorganisms are crucial in dissolving fertilizer phosphorus and bound phosphorus in soil in a manner that is both environmentally friendly and sustainable. In this study, we selected yeasts with calcium-phosphate-solubilizing ability and found that this ability to be regulated by environmental factors (e.g. amount of soluble phosphate, liquid or solid agar plates condition, and type of inorganic phosphate). Arabidopsis thaliana was inoculated with selected yeasts; we found that Cryptococcus laurentii (JYC370) promoted plant growth in an inorganic phosphate (Pi)-deficient medium supplemented with calcium phosphate dibasic dihydrate. The amount of cellular inorganic phosphate was also higher in yeast-treated plants than in control plants grown in the Pi-deficient medium. This result reveals the potential of these strains for biofertilizer applications and commercial use as biofertilizer agents in the future.