The invention relates to a composition for stimulating the development of plants, comprising at least one strain of Tsukamurella paurometabola, a biofertiliser agent which optimises the use of organic material by plants, facilitating the assimilation of nitrogen and phosphorus. Said agent can increase the growth and development of plants when applied directly to the soil or to a natural or artificial substrate containing an organic material, or when applied to any kind of soil or substrate containing an organic supplement.