Abstract: The invention relates to a solid-state fermenter for the cultivation of micro-organisms on solid substrates, in particular for large volumes. The field of application of the invention is the microbiological industry. The solid-state fermenter according to the invention comprises one or more air-proof and waterproof fermenter levels arranged on top of one another, connected with the wall of the container in such a way that neither air nor water can flow past laterally, with a culture substrate to be found on the fermenter levels for the micro-organisms to be cultivated, and wherein the cooling of the fermenter material is done by cooling lances rising vertically from the fermenter base and leading through the fermenter levels (4) and a seal (6) is installed between the fermenter levels (4), which is pressed against the inner wall of the fermenter by the mass of the level above it (4).