Indigo-25 is a biological preparation intended for use in agriculture. The preparation is applied for pre-sowing treatment of cereal crops such as wheat and barley. The preparation contains a live bacterial culture of Kosakonia cowanii SYM00028 with a total bacterial titre of not less than 1*107 CFU/ml. The use of this preparation is single application, at a rate of 2 liters per ton of seeds. The preparation is in the form of a water emulsion and is suitable for use in agronomic practices aimed at improving seed quality and increasing crop yields.