Plate colonization of Methanococcus maripaludis and Methanosarcina thermophila in a modified canning jar

Abstract Conditions have been optimized for colonization of fastidiously anaerobic microorganisms on solidified plating medium incubated in modified canning jars. Two species of methanogenic Archaea, the mesophilic, hydrogen utilizer Methanococcus maripaludis and the moderately thermophilic methylotroph Methanosarcina thermophila , were grown with high efficiency on agar-solidified medium in petri plates. Maximum colony size and plating efficiencies of 50–100% of total cell counts were obtained by optimizing inoculation method, H₂S concentrations, and agar moisture content. The simple modifications required provide a readily available source of inexpensive anaerobic growth vessels for investigations requiring colonization of methanogens on solidified plating medium.