Yarrowia lipolytica as a Phosphate-Solubilizing Yeast for Plant Growth Promotion

Abstract Background Phosphorus (P) availability is a major constraint to crop production in highly weathered tropical soils, highlighting the need for sustainable alternatives to improve P use efficiency. This study evaluated the plant growth-promoting potential of Yarrowia lipolytica through in vitro characterization and greenhouse experiments. Results The yeast exhibited high calcium phosphate solubilization (71.2%), lower solubilization of iron and aluminum phosphates, and the ability to mineralize phytate (6.75 mg L − 1 ). Acidification of the culture medium, together with high acid and alkaline phosphatase activities, indicated that organic acid production and phosphatase secretion were the main mechanisms involved in P mobilization. The yeast also produced the phytohormones indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA), supporting an additional mechanism for plant growth promotion. Under greenhouse conditions, inoculation significantly increased plant height, stem diameter, fruit number, and fruit yield of Micro-Tom tomato, with the greatest responses observed at the highest inoculation dose. In contrast, no significant effects were detected in rice, bean, or maize grown in a highly weathered, nutrient-poor soil, although inoculated plants consistently showed a positive growth trend. Conclusions Overall, Y. lipolytica exhibits multiple plant growth-promoting traits, particularly those related to phosphorus mobilization and phytohormone production, demonstrating its potential as an agricultural bioinput. However, its effectiveness in promoting plant growth depends on substrate fertility, the availability of compatible phosphorus sources, and inoculation dose.