ISOLATION OF NEW METHANOL-UTILIZING BACTERIA AND ITS THIAMINE-REQUIREMENT FOR GROWTHS

Non-pigmented methanol-dependent bacteria have been isolated in pure culture from a wide variety of natural sources. They are capable of growing only on methanol among many carbon sources tested, and showed no growth on ordinary nutrient media. These bacteria were identified as a new species, Methanomonas methylovora. The organisms are gram-negative, non- sporeforming rods, 0.4 to 0.7μ by 1.0 to 4.0μ in size, having a single polar flagellum. GC content of DNA is 51.2 to 53.6%. Some of them required a relatively high concentration of thiamine as an essential factor for cell growth, and produced an intracellular yellow pigment on methanol-containing agar medium.