PLATE COLONIZATION OF METHANOCOCCUS-MARIPALUDIS AND METHANOSARCINA-THERMOPHILA IN A MODIFIED CANNING JAR

Conditions have been optimized for colonization of fastidiously anaero bic microorganisms on solidified plating medium incubated in modified canning jars. Two species of methanogenic Archaea, the mesophilic, hyd rogen utilizer Methanococcus maripaludis and the moderately thermophil ic methylotroph Methanosarcina thermophila, were grown with high effic iency on agar-solidified medium in petri plates. Maximum colony size a nd plating efficiencies of 50-100% of total cell counts were obtained by optimizing inoculation method, H2S concentrations, and agar moistur e content. The simple modifications required provide a readily availab le source of inexpensive anaerobic growth vessels for investigations r equiring colonization of methanogens on solidified plating medium.