Procedures for the isolation and characterization of Metha7zonzo?zas n~ethatto-oxidans Brown and Strawinslii are described. Isolates from varied sources are alike in cellular morphology, inasmuch a s they form only microcolonies, and in their dependence on methane or methanol as carbon and energy sources for growth. Both organic and inorganic nitrogen sources are used. The organism is a Gram negative non-sporeformillg rod, 1.5 to 3.0 p by 1.0 p in size, and motile by means of a single polar flagellum. In growing cultures the osygen/methane ratio was approsinlately 1.1 and in resting cells 1.7. The R.Q. for methane with resting cells was 0.43. Resting cells were unable t o oxidize organic compounds other than methane, methanol, formaldehyde, and formate. Formic acid was detected in test solutions after cell suspensions had metabolized methane, methanol, and formaldehyde. Using sodium sulphite as trapping agent for formaldehyde, it was found that 60 t o 70y0 of the methane or methanol consumed was converted to formaldehyde. I n the presence of iodoacetate, 70% of the methane consumed was present terminally as methanol. Thus i t was shown that methanol, formaldehyde, and formic acid are sequential intermediates in the osidation of methane by these organisms.In 1905 Kaserer concluded that inethane was oxidized by bacteria but he did not attempt t o isolate the responsible organisms. Shortly thereafter Sohngen (16) described a methane-oxidizing bacterium which he named Bacillus methanicz~s. Since that time, bacteria capable of utilizing inethane have been reported by inany ~vorlters including Munz (13), Giglioli and Masoni (9), Aiyer (I), A4ogilevsltii (12), Boltova, Kusnetsova, and I

Conditions have been established for the oxidation of naphthalene by a pseudomonad based on the yields of ether extractable substances. Vigorous aeration yielded approximately three times the product obtained from unaerated controls. Oxidations with media adjusted initially to pH 8 gave higher yields than those adjusted to lower pH levels. Calcium and copper appeared to be necessary for maximum yields. Under the conditions described, the non-naphthalenic ether extractable substances amounted to as much as 29% of the original 1% naphthalene. Purification and analysis of the crude extract showed that it consisted largely of salicylic acid. Some properties of the remaining material are described.

Little information has been contributed to the mechanisms of biological degradation of polycyclic hydrocarbons. The oxidation of naphthalene has received the most attention. Strawinski and Stone (1943, 1954) reported the isolation of substantial amounts of salicylic acid ("most" of the 2.9 mg per ml medium of ether extractable product) from the breakdown of naphthalene by Pseudomonas aeruginosa. Salicylic acid has been verified as an intermediate in naphthalene oxidation by Treccani (1953), Walker and Wiltshire (1953), and Murphy and Stone (1955). These latter systems were not entirely satisfactory for intermediary studies. Either the intermediate compound (salicylate) was recovered in small amounts; i.e., 23 mg from 2 L culture medium (Walker and Wiltshire, 1953), 0.6 mg per ml medium (Murphy