With the company Reciclados Palancia Belcaire, we have worked on the development of a fertilizer enriched with biostimulant microorganisms, from biostabilized material and compost resulting from the treatment of the organic fraction of municipal solid waste. To this end, AINIA optimized the lactic fermentation process through bioaugmentation and modification of operating variables; the bacteria present with biostimulant capacity were isolated and subjected to a microencapsulation process. The final product was tested in combination with biostabilized material, compost, and conventional fertilizer. The company received funding from the Valencian Innovation Agency to carry out this project.