Micrococcus lactis sp. nov., isolated from dairy industry waste

Abstract

A Gram-positive, yellow-pigmented, actinobacterial strain, DW152T, was isolated from a dairy industry effluent treatment plant. 16S rRNA gene sequence analysis indicated that strain DW152T exhibited low similarity with many species with validly published names belonging to the genera Micrococcus and Arthrobacter. However, phenotypic properties including chemotaxonomic markers affiliated strain DW152T to the genus Micrococcus. Strain DW152T had ai-C15 : 0 and i-C15 : 0 as major cellular fatty acids, and MK-8(H2) as the major menaquinone. The cell-wall peptidoglycan of strain DW152T had l-lysine as the diagnostic amino acid and the type was A4α. The DNA G+C content of strain DW152T was 68.0 mol%. In 16S rRNA gene sequence analysis, strain DW152T exhibited significant similarity with Micrococcus terreus NBRC 104258T, but the mean value of DNA–DNA relatedness between these strains was only 42.3 %. Moreover, strain DW152T differed in biochemical and chemotaxonomic characteristics from M. terreus and other species of the genus Micrococcus. Based on the above differences, we conclude that strain DW152T should be treated as a novel species of the genus Micrococcus, for which the name Micrococcus lactis sp. nov. is proposed. The type strain of Micrococcus lactis sp. nov. is DW152T ( = MTCC10523T  = DSM 23694T).