Abstract
Three indigo-reducing obligately alkaliphilic strains, M3T, 41A and 41C, were isolated. The isolates grew at pH 912, but not at pH 78. They were Gram-positive, facultatively anaerobic, straight rod-shaped strains with peritrichous flagella. The isolates grew in 014 % (w/v) NaCl, with optimum growth at 313 %. They grew at temperatures between 10 and 45 °C, with optimum growth at around 3037 °C. They did not hydrolyse starch or gelatin. DL-lactate was the major end-product from D-glucose. No quinones could be detected. The peptidoglycan type was A4β, OrnD-Asp. The major cellular fatty acids were C16 : 0, C16 : 17c and C18 : 19c. The DNA G+C content was 42·643·2 mol%. Phylogenetic analysis based on 16S rRNA gene sequence data indicated that the isolates belong to the genus Alkalibacterium. DNADNA hybridization revealed low similarity (less than 16 %) of the isolates with respect to the two closest phylogenetically related strains, Alkalibacterium olivapovliticus and Alkalibacterium psychrotolerans. On the basis of phenotypic and chemotaxonomic characteristics, phylogenetic data and DNADNA relatedness, the isolates merit classification as a novel species of the genus Alkalibacterium, for which the name Alkalibacterium iburiense is proposed. The type strain is M3T (=JCM 12662T=NCIMB 14024T).