The strain Bacillus subtilis IMV B-7023 is part of the complex bacterial preparation Azogran for crop production. This bacterium has the ability to increase the availability of phosphorus for plants through the synthesis of different organic acids. Using GS-MS, the qualitative and quantitative composition of organic acids in the culture medium of bacilli was investigated depending on the source of phosphorus nutrition in the nutrient medium. It was established that B. subtilis IMV B-7023 synthesizes the greatest amount of organic acids at cultivation in a glucose-mineral medium with calcium glycerophosphate after 24 hours. Among them: acetic, isobutyric, butyric, isovaleric, valeric, caproic, enanthic, caprylic, pelargonic. The content of the acetic acid was 32.5 µg/mL and prevailed over other acids. In the presence of calcium glycerophosphate as the sole source of carbon and phosphate nutrition, the concentration of butyric acid increased by 14.5 µg/mL, valeric – by 17.0 µg/mL, caproic – by 36.6 µg/mL, caprylic – by 9.3 µg/mL, and pelargonic – by 13.1 µg/mL, compared with the previous variant. In the presence of Ca3(PO4)2, B. subtilis IMV B-7023 produced the acetic and isobutyric acids. The concentrations of these compounds reached a maximum (300.0 and 90.0 μg/mL) after 48 hours of cultivation of bacteria, and then decreased.