The Growth of Dictyostelium discoideum upon Pathogenic Bacteria

Abstract

Species of the Dictyosteliaceae, a group of pseudoplasmodium-forming slime molds, are not uncommon in nature and can be readily isolated from soils, from decaying vegetation and from the dung of various animals. In contrast to the Myxogastrales which possess true plasmodia, the Dictyosteliaceae are characterized by myxamoebae which retain their identity throughout the whole life cycle of the organisms. During the vegetative stage these myxamoebae are free-living and feed by the ingestion and digestion of bacterial cells. With the exhaustion of the available food supply, the myxamoebae collect into aggregates termed pseudoplasmodia, and collectively build fruiting structures, or sorocarps. In these structures some myxamoebae become transformed into sterile, supportive cells to form a stalk, or sorophore, while others become differentiated into fertile spores forming a spore head, or sorus. The ubiquitous species Dictyostelium mucoroides Bref. has been more widely studied than other members of the group and from the work of Vuillemin (1902), Potts (1902), Pinoy (1903 and 1907), and Schuckmann (1924) a limited bacterial "host range" embracing twelve different species has been reported for it.