POLYPHASIC CHARACTERIZATION OF THE GENUS LEPTOTHRIX - NEW DESCRIPTIONS OF LEPTOTHRIX MOBILIS SP-NOV AND LEPTOTHRIX DISCOPHORA SP-NOV NOM REV AND EMENDED DESCRIPTION OF LEPTOTHRIX CHOLODNII EMEND

Strain Feox-1 was isolated from the sediment of a big freshwater lake (Chiemsee) in Upper Bavaria, Germany. The site of isolation was charac terized by dark-brown ferromanganese deposits produced by sheared bact eria belonging to the genus Leptothrix. Cells of the newly isolated st rain were gram-negative, rod-shaped and highly motile by a single pola r flagellum. Although sheaths were not formed strain Feox-1 could be a ffiliated to the genus Leptothrix by its ability to oxidize manganese at circumneutral pH values. A polyphasic approach was used to determin e the taxonomic status of Feox-1 and of the other currently available Leptothrix strains which have been only partly described. Physiologica l tests, fatty acid analyses, DNA-DNA hybridization experiments and se quencing of 16S rRNA genes indicated that Feox-1 belongs to a new spec ies, for which the name Leptothrix mobilis is proposed. Main character istics of the newly proposed species are as follows: Good growth occur s in the range of 10 to 37 degrees C and pH 6.5 to 8.5. Only very few compounds are utilized as sole carbon source. Cells contain as major f atty acids hexadecanoic acid, cis-9-hexadecenoic acid and octadecenoic acid; minor fatty acids are 3-hydroxydecanoic acid, dodecanoic acid, tetradecanoic acid and cis-9,10-methyleneactadecanoic acid. The guanin e-plus-cytosine content of the DNA is 68 mol%. Taxonomic studies of st rains belonging to the non-validly described species ''Leptothrix disc ophora'' and to Leptothrix cholodnii led to the description of Leptoth rix discophora sp. nov. nom. rev. and to an emended description of Lep tothrix cholodnii. In addition, the two strains LMG 8142 and LMG 8143 originally assigned to ''Leptothrix discophora'' were transferred to L eptothrix cholodnii.