No abstract

Within the framework of our genome-based program to discover new antibiotic lipopeptides from Pseudomonads, brabantamides A-C were isolated from plant-associated Pseudomonas sp. SH-C52. Brabantamides A-C displayed moderate to high in vitro activities against Gram-positive bacterial pathogens. Their shared structure is unique in that they contain a 5,5-bicyclic carbamate scaffold. Here, the biosynthesis of brabantamide A (SB-253514) was studied by a combination of bioinformatics, feeding experiments with isotopically labelled precursors and in vivo and in vitro functional analysis of enzymes encoded in the biosynthetic pathway. The studies resulted in the deduction of all biosynthetic building blocks of brabantamide A and revealed an unusual feature of this metabolite: its biosynthesis occurs via an initially formed linear di-lipopeptide that is subsequently rearranged by a novel FAD-dependent Baeyer-Villiger monooxygenase.

Strain PB-6250T, isolated from soil in Japan, was first identified in 1992. In contrast to its original taxonomic classification, its 16S rRNA gene sequence showed the highest similarity (99.2 %) to the sequence of Lysobacter enzymogenes DSM 2043T, with Lysobacter antibioticus DSM 2044T being the next most closely related species (98.7 %) with a validly published name. Chemotaxonomic data (fatty acid profile, quinone and polar lipid composition) and the G+C content of strain PB-6250T were compared with those of the closely related type strains L. enzymogenes LMG 8762T, L. antibioticus LMG 8760T, L. capsici DSM 19286T and L. gummosus LMG 8763T; this supported the affiliation of strain PB-6250T to the genus Lysobacter. Phylogenetic analyses, DNA-DNA-hybridization data, biochemical and physiological characteristics strongly supported the genotypic and phenotypic differentiation of strain PB-6250T from species of Lysobacter with validly published names. Strain PB-6250T, therefore represents a novel species, for which the name Lysobacter firmicutimachus sp. nov. is proposed. The type strain is PB-6250T (=LMG 28994T=DSM 102073T).

Strain ATCC 31962 was formerly taxonomically classified as Empedobacter haloabium and reported to be the producer of the lipopeptide antibiotic empedopeptin. Here, we report the draft genome sequence of ATCC 31962, which encodes regions that suggest a distinct biosynthetic capacity and suggests its taxonomic reclassification.