Pure cultures of methane-oxidizing bacteria isolated from soil, from the rumen of a fistulated cow, and from coalmine water were found to be identical in morphological, cultural, and physiological characteristics with Methanoojonas otiethanooxidoans of Brown and Strawinski. Two of the isolates were serologically related to the organism of Brown and Strawinski. All the strains required methane for good growth, but a delayed moderate growth occurred on methanol. No other substanices were utilized as carbon and energy source. Nitrogen re(luirements were satisfied by nitrates, anuimonium salts, peptone, or certain amnino acids. The taxonomic position of the species is discussed. Since the first description of methane-oxidizing bacteria by S6hngen (1906), numerous investigators have relported studies dealing with microbial oxidation of methane and other gaseous hYdrocarbons. Among the more recent rel)orts are those of Hutton and ZoBell (1949), Dworkin and Foster (1956), Strawinski and Brown (1957), B3rown and Strawinski (1957, 1958), and Leadbetter and Foster (1958). Recent reviews of hydrocarbon oxidation by microorganisms have been provided 1y Fuhs (1961) and Foster (1962). In most reports dealing with methane-oxidizing bacteria, the descriptions of the organisms involved have been inadequate to afford detailed coml)arison with those described by other investi'rators, and the cultures are not available for coml)arative studies. This rep)ort describes the methods employed in the isolation of three additional strains of methane-dependent organisms, an(d compares them with the organism named Alethanomonas nmethanooxidans bv Brown and Strawinski (1958).

Baton lRouge), AND C. S. MCCLESKEY. Identity of the pink-pigmented methanol-oxidizing bacteria as Vib:-io extorquens. J. Bacteriol. 88:1065-1070. 1964.-Pink-pigmented bacteria isolated from enrichnment cultures of methane oxidizers were found to possess similar morphological, cultural, and physiological characteristics. All the strains utilized methanol, formate, oxalate, succinate, glycerol, and benzene as sole carbon sources; methanol, formate, and glycerol afforded best growth. Most strains utilized fructose and ribose; other carbohydrates tested were not available as carbon and energy sources. There was strain variation in the use of hexane, heptane, n-propanol, n-butanol, acetate, and propionate. Methane, ethane, n-propane, and n-butane were not utilized. Our isolates, and Pseudonmonas tnethanica of Harrington and Kallio (not the methane-de

Growth and sporulation cycles of Rhizopus nigricans were compared using 23 amino acids and 2 inorganic compounds as nitrogen sources.When supplied individually, all monoamino-monocarboxylic acids supported growth. Heaviest mycelium was obtained from arginine, glycine, ornithine, or alanine. No growth was observed in lysine, cystine, cysteine, tyrosine, dihydroxy-phenylalanine, histidine, or tryptophan. When the amino acids were supplied as a mixture by a process of single elimination, most rapid germination occurred in the absence of valine or aspartic acid. Greatest initial growth was observed when arginine, lysine, aspartic acid, or leucine were omitted. Most profuse growth after a period of 15 hours was noted in the absence of cystine, serine, or aspartic acid. Earliest sporulation took place when aspartic acid, tyrosine, threonine, or dihydroxyphenylalanine were omitted. Organisms produced an acidic reaction in the media which retarded growth considerably,Unexplained similarities between germination–sporulation responses observed and those reported for the genus Bacillus may be of interest or significance.

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