The invention relates to a fungal strain of the genus Trichoderma with the designation HSA12 and to compositions that contain said fungal strain or spores thereof. The invention further relates to the use of the fungal strain or spores thereof in different methods, for example in a method for promoting and/or stabilizing plant growth and/or for increasing the yields of cultivated plants, which methods comprise inoculating soil, roots and/or above-ground plant parts with the fungal strain or spores with compositions containing said fungal strain or spores thereof, in order, inter alia, to increase the efficiency of nutrient intake and to improve the stress tolerance of cultivated plants. The invention further relates to the use of the fungal strain or spores thereof in a method for improving the structure and health of the soil or for decontaminating or remediating soil or a body of water and in a method for stabilizing or reestablishing endangered or desired wild plant populations. The invention further relates to a set of primer pairs for amplifying microsatellite loci of the genome of the fungal strain in order to determine molecular markers and to identify the fungal strain, and to a method for determining the fungal strain.
