Micrococcus flavus sp nov., isolated from activated sludge in a bioreactor

Bacterial strain LW4(T) was isolated from activated sludge of a wastewater-treatment bioreactor. Cells of strain LW4(T) were Gram-positive cocci, with a diameter of 0.7-1.0 pm. Colonies produced on LB agar plates were yellow, smooth, circular and 0.5-1.5 mm in diameter. Strain LW4T was aerobic and grew over the temperature range 26-34 degrees C and pH range 5-9, with optimal growth at 30.5-31.5 degrees C and pH 6.0-6.2. The cell-wall peptidoglycan of strain LW4(T) contained amino acid residues of lysine, glutamic acid, alanine, glycine and aspartic acid. The most abundant cellular fatty acids of strain LW4(T) were anteiso-C-15:0 (32.15%) and isoC(15:0) (31.65%). Major respiratory quinones were MK-8(H-2) (57.3%) and MK-7(H-2) (32.9%). The DNA G+C content was 71.4 mol% (T-m). 16S rRNA gene sequence analysis indicated that strain LW4(T) was phylogenetically related to members of the genus Micrococcus, with similarities ranging from 96.5 to 97.3%. Levels of DNA-DNA relatedness of strain LW4(T) to Micrococcus luteus DSM 20030(T), Micrococcus lylae DSM 20315(T) and Micrococcus antarcticus AS 1.2372(T) were 55, 48 and 36%, respectively. Based on these results, it is concluded that strain LW4(T) represents a novel species of the genus Micrococcus, for which the name Micrococcus flavus sp. nov. is proposed. The type strain is strain LW4(T) (= CGMCC 1.5361(T) = JCM 14000(T)).