Roselyn Brown

Gordonia amicalis sp. nov., a novel dibenzothiophene-desulphurizing actinomycete

The taxonomic position of a dibenzothiophene-desulphurizing soil actinomycete was established using a polyphasic taxonomic approach. The organism, strain IEGMT, was shown to have chemical and morphological properties typical of members of the genus Gordonia. The tested strain formed a distinct phyletic line within the evolutionary radiation occupied by the genus Gordonia, with Gordonia alkanivorans DSM 44369T, Gordonia desulfuricans NCIMB 40816T and Gordonia rubropertincta DSM 43197T as the most closely related organisms. Strain IEGMT has a range of phenotypic properties that distinguish it from representatives of all of the validly described species of Gordonia. It was also sharply distinguished from the type strains of Gordonia desulfuricans and Gordonia rubropertincta on the basis of DNA-DNA relatedness data. The combined genotypic and phenotypic data show that strain IEGMT merits recognition as a new species of Gordonia. The name proposed for the new species is Gordonia amicalis; the type strain is IEGMT (= DSM 44461T = KCTC 9899T).

Diversity of culturable actinomycetes in hyper-arid soils of the Atacama Desert, Chile

The Atacama Desert presents one of the most extreme environments on Earth and we report here the first extensive isolations of actinomycetes from soils at various locations within the Desert. The use of selective isolation procedures enabled actinomycetes to be recovered from arid, hyper-arid and even extreme hyper-arid environments in significant numbers and diversity. In some cases actinomycetes were the only culturable bacteria to be isolated under the conditions of this study. Phylogenetic analysis and some phenotypic characterisation revealed that the majority of isolates belonged to members of the genera Amycolatopsis, Lechevalieria and Streptomyces, a high proportion of which represent novel centres of taxonomic variation. The results of this study support the view that arid desert soils constitute a largely unexplored repository of novel bacteria, while the high incidence of non-ribosomal peptide synthase genes in our isolates recommend them as promising material in screening for new bioactive natural products.

Caboxamycin, a new antibiotic of the benzoxazole family produced by the deep-sea strain Streptomyces sp. NTK 937*

Caboxamycin, a new benzoxazole antibiotic, was detected by HPLC-diode array screening in extracts of the marine strain Streptomyces sp. NTK 937, which was isolated from deep-sea sediment collected in the Canary Basin. The structure of caboxamycin was determined by mass spectrometry, NMR experiments and X-ray analysis. It showed inhibitory activity against Gram-positive bacteria, selected human tumor cell lines and the enzyme phosphodiesterase.

Corynebacterium mooreparkense sp. nov. and Corynebacterium casei sp. nov., isolated from the surface of a smear-ripened cheese

Ten isolates each of two different bacterial species isolated from the surface of a smear-ripened cheese were found to exhibit many characteristics of the genus Corynebacterium. The isolates were Gram-positive, catalase-positive, non-spore-forming rods that did not undergo a rod/coccus transformation when grown on complex media. Chemotaxonomic investigation revealed that the strains belonged unambiguously to the genus Corynebacterium. Their cell walls contained arabinose, galactose and short-chain mycolic acids (C22 to C36) and their peptidoglycan contained meso-diaminopimelic acid. The G+C content of the DNA was 51-60 mol%. MK-9 (H2) was the principal menaquinone. The 16S rDNA sequences of four isolates of each bacterium were determined and aligned with those of other members of the coryneform group. Phylogenetic analysis showed that the strains represented two new sublines within the genus Corynebacterium; Corynebacterium variabile and Corynebacterium ammoniagenes were their nearest known phylogenetic neighbours. Corynebacterium variabile and Corynebacterium ammoniagenes showed the highest levels of sequence homology with the isolates; however, DNA-DNA hydridization studies indicated that the Corynebacterium strains isolated from the cheese smear did not belong to either Corynebacterium variabile or Corynebacterium ammoniagenes (26 and 46% chromosomal similarity, respectively). On the basis of the phylogenetic and phenotypic distinctiveness of the unknown isolates, it is proposed that the bacteria be classified as two new Corynebacterium species, for which the names Corynebacterium mooreparkense sp. nov. and Corynebacterium casei sp. nov. are proposed. Type strains have been deposited in culture collections as Corynebacterium mooreparkense LMG S-19265T (= NCIMB 30131T) and Corynebacterium casei LMG S-19264T (= NCIMB 30130T).

Microbacterium gubbeenense sp. nov., from the surface of a smear-ripened cheese.

Phenotypic and phylogenetic studies were performed on 11 strains of a Microbacterium-like organism isolated from the surface of a smear-ripened cheese. The isolates were Gram-positive, catalase-positive, facultatively anaerobic, oxidase-negative, non-spore-forming, non-motile, small, slender rods and grew in 12% (w/v) NaCl. Chemotaxonomic investigation revealed that all the isolates belonged unambiguously to the genus Microbacterium. They contained type B1 peptidoglycans with L-lysine as the diamino acid and glycolyl acyl types; rhamnose and galactose were the cell wall sugars. The G+C content ranged from 69 to 72 mol%. The major menaquinones were MK-11 and MK-12 and the major fatty acids were anteiso C15:0 and C17:0 and iso C16:0. Phylogenetic analysis of the 16S rRNA sequences of four isolates showed that they represented a new subline in the genus Microbacterium, with Microbacterium barkeri as their nearest phylogenetic neighbour. M. barkeri showed the highest sequence similarity to the isolates; however, DNA-DNA hybridization showed that the isolates had only 38% chromosomal similarity to M. barkeri. Based on the phylogenetic and phenotypic distinctiveness of the isolates, it is proposed that they be classified as a new Microbacterium species, for which the name Microbacterium gubbeenense sp. nov. is suggested. The type strain has been deposited as LMG S-19263T (= NCIMB 30129T). The GenBank accession number for the 16S rDNA sequence of the type strain is AF263563.

Gordonia desulfuricans sp. nov., a benzothiophene-desulphurizing actinomycete

The taxonomic position of two actinomycetes isolated from soil was established using a polyphasic approach. The organisms, designated 213ET and 213F, were found to have chemical and morphological properties consistent with their assignment to the genus Gordonia. Nearly complete sequences of the 16S rDNA genes of the two strains were determined following the isolation and direct sequencing of the amplified genes. The tested strains were found to have identical 16S rDNA sequences and formed a phylogenetic line within the evolutionary radiation occupied by the genus Gordonia that was most closely related to Gordonia rubropertincta DSM 43197T. However, DNA-DNA relatedness data showed that strain 213ET and Gordonia rubropertincta DSM 43197T belonged to distinct genomic species. Strains 213ET and 213F also shared an identical phenotypic profile which distinguished them from representatives of validly described Gordonia species. The combined genotypic and phenotypic data show that strains 213ET and 213F merit recognition as a new species of Gordonia. The name proposed for the new species is Gordonia desulfuricans, for which the type strain is 213ET (= NCIMB 40816T).

Albidopyrone, a new α-pyrone-containing metabolite from marine-derived Streptomyces sp. NTK 227

Albidopyrone, a new α-pyrone-containing secondary metabolite, was produced by Streptomyces sp. NTK 227, a strain isolated from Atlantic Ocean sediment and found to be a member of the Streptomyces albidoflavus 16S rRNA gene clade. The structure of the compound was determined by MS and NMR spectroscopy, and found to have a moderate inhibitory activity against protein-tyrosin phosphatase B.