Apparatus for the automatic testing of substances for potential carcinogenicity, comprising: - a plate support on which at least one micro-well plate can be placed, the micro-well plate comprising a plurality of substance/salmonella mixtures or substance/salmonella/liver enzymes mixtures in the respective wells of the plate; - a movable pipetting unit comprising a predetermined number of pipettes, wherein the pipettes of the pipetting unit are arranged at an inclination angle (α, -α) relative to a normal to the plane of the plate support; - a dish support on which a corresponding number of dishes can be placed, each dish having a bottom and an upstanding side wall surrounding the bottom as well as a solid culture medium arranged on the bottom of the dish; - spinning means for spinning the dishes; - closing means for placing a lid on each of the dishes so as to close the respective dishes; - transport means (64,65) for transporting the closed dishes to an intermediate storage capable of collecting a plurality of closed dishes so as to forward them to an incubator, characterized in that - adjacently arranged pipettes of the pipetting unit are arranged at opposite inclinations (α, -α) relative to the normal, wherein the angle (α, -α) is in the range up to 10° relative to the normal such that it is possible to use standard pipette tips and 96 well micro-well plates and to introduce adjacently arranged pipette tips into adjacently arranged wells of the micro-well plate without collision; - the apparatus comprises a number of containers containing a liquid culture medium, the number of containers corresponding to the number of pipettes of the pipetting unit; - the apparatus comprises heating means which are capable of being positioned above the respective solid culture medium arranged in the respective dishes on the dish support, wherein the heating means comprise a number of IR-heaters (70,71) corresponding to the number of dishes that can be arranged on the dish support at the same time. - a plate support on which at least one micro-well plate can be placed, the micro-well plate comprising a plurality of substance/salmonella mixtures or substance/salmonella/liver enzymes mixtures in the respective wells of the plate; - a movable pipetting unit comprising a predetermined number of pipettes, wherein the pipettes of the pipetting unit are arranged at an inclination angle (α, -α) relative to a normal to the plane of the plate support; - a dish support on which a corresponding number of dishes can be placed, each dish having a bottom and an upstanding side wall surrounding the bottom as well as a solid culture medium arranged on the bottom of the dish; - spinning means for spinning the dishes; - closing means for placing a lid on each of the dishes so as to close the respective dishes; - transport means (64,65) for transporting the closed dishes to an intermediate storage capable of collecting a plurality of closed dishes so as to forward them to an incubator, - adjacently arranged pipettes of the pipetting unit are arranged at opposite inclinations (α, -α) relative to the normal, wherein the angle (α, -α) is in the range up to 10° relative to the normal such that it is possible to use standard pipette tips and 96 well micro-well plates and to introduce adjacently arranged pipette tips into adjacently arranged wells of the micro-well plate without collision; - the apparatus comprises a number of containers containing a liquid culture medium, the number of containers corresponding to the number of pipettes of the pipetting unit; - the apparatus comprises heating means which are capable of being positioned above the respective solid culture medium arranged in the respective dishes on the dish support, wherein the heating means comprise a number of IR-heaters (70,71) corresponding to the number of dishes that can be arranged on the dish support at the same time.