BackgroundBacteriocins are antimicrobial peptides that are produced by bacteria as a defense mechanism in complex environments. Identification and characterization of novel bacteriocins in novel strains of bacteria is one of the important fields in bacteriology.Methodology/FindingsThe strain GI-9 was identified as Brevibacillus sp. by 16 S rRNA gene sequence analysis. The bacteriocin produced by strain GI-9, namely, laterosporulin was purified from supernatant of the culture grown under optimal conditions using hydrophobic interaction chromatography and reverse-phase HPLC. The bacteriocin was active against a wide range of Gram-positive and Gram-negative bacteria. MALDI-TOF experiments determined the precise molecular mass of the peptide to be of 5.6 kDa and N-terminal sequencing of the thermo-stable peptide revealed low similarity with existing antimicrobial peptides. The putative open reading frame (ORF) encoding laterosporulin and its surrounding genomic region was fished out from the draft genome sequence of GI-9. Sequence analysis of the putative bacteriocin gene did not show significant similarity to any reported bacteriocin producing genes in database.ConclusionsWe have identified a bacteriocin producing strain GI-9, belonging to the genus Brevibacillus sp. Biochemical and genomic characterization of laterosporulin suggests it as a novel bacteriocin with broad spectrum antibacterial activity.

A Gram-positive, yellow-pigmented, actinobacterial strain, DW152 T , was isolated from a dairy industry effluent treatment plant. 16S rRNA gene sequence analysis indicated that strain DW152 T 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 DW152 T had ai-C 15 : 0 and i-C 15 : 0 as major cellular fatty acids, and MK-8(H 2 ) as the major menaquinone. The cell-wall peptidoglycan of strain DW152 T had L-lysine as the diagnostic amino acid and the type was A4a.The DNA G+C content of strain DW152 T was 68.0 mol%. In 16S rRNA gene sequence analysis, strain DW152 T 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 DW152 T 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 DW152 T (5MTCC10523 T 5DSM 23694 T ).