The invention relates to a liquid preparation comprising biologically active fungi and/or fungal organs and/or other microorganisms in a suspension, to a method for producing it and to the use thereof for biological protection of plants, for biological plant strengthening, or for biological soil improvement. Polyether-modified trisiloxane is a preferred liquid used. The preparation according to the invention is notable for easily manageable storage at room temperature, trouble-free transport, and simplicity of production and application.
