The objective of this study was to evaluate the efficiency of fungus Aspergillus niger M22 in phosphate solubilization in liquid medium and lettuce development. Both Araxá phosphate and rock residue were added at the dose of 3 g to 100 mL of culture medium yeast extract glucose. The phosphate treatments were inoculated with 1 mL of fungal culture containing 108 UFC mL-1 incubated at 28° C under 190-rpm shaking, for eight days. Both pH and P content were evaluated at the end of the incubation period. To evaluate the potential of M22 in solubilizing nutrients for lettuce plants, combinations of pellets of Aspergillus nigers isolate, of Araxá apatite rock and fertilizer were used as treatments. Isolate M22 presented a higher amount of P soluble in Araxá phosphate than in phosphate rock residue. M22 increased about four times the amount of P soluble in Araxá phosphate medium in relation to the control and about three times in the medium with phosphate rock residue. Isolate M22 demonstrated capacity of solubilizing phosphates. Araxá apatite rock possesses potential to be utilized as a source of phosphorus and potassium.