Summary auto-generated
Three airborne bacterial strains (I/26-Cor1T, I/32A-Cor1, and I/74-Cor2) were collected from the Museo Correr in Venice and characterized using biochemical, physiological, chemotaxonomic, and molecular genetic analyses. All three strains were Gram-negative, rod-shaped, red-pigmented bacteria that resembled members of the genus Hymenobacter. Comprehensive testing including 16S rRNA gene sequencing, DNA G+C content determination (60-63 mol%), fatty acid analysis, menaquinone composition (MK-7 predominant), and genomic fingerprinting was performed. Strains I/26-Cor1T and I/32A-Cor1 showed nearly identical characteristics across all analyses, with only minor differences in genomic fingerprints and polar lipid profiles. Both strains shared 95.8% 16S rRNA gene sequence similarity with Hymenobacter actinosclerus. Based on their unique combination of physiological and molecular characteristics, the authors propose these two strains represent a novel species, Hymenobacter aerophilus sp. nov., with I/26-Cor1T as the type strain. Strain I/74-Cor2 was designated as Hymenobacter sp. I/74-Cor2 due to ambiguous taxonomic status within the genus Hymenobacter.
Key findings
- Three red-pigmented airborne bacteria from Venice museum air were identified as members of genus Hymenobacter with unusually high genomic G+C content (60-63 mol%) compared to other Cytophaga-Flavobacterium-Bacteroides group members
- Strains I/26-Cor1T and I/32A-Cor1 are proposed as novel species Hymenobacter aerophilus sp. nov., sharing >95% 16S rRNA similarity and nearly identical physiological and chemotaxonomic characteristics
- The new species exhibits characteristic menaquinone MK-7, meso-diaminopimelic acid cell wall composition, and specific fatty acid and polar lipid profiles that distinguish it from related Hymenobacter species
- Strain I/74-Cor2 remains taxonomically uncertain within Hymenobacter but shows closer phylogenetic relationship to H. actinosclerus than to H. roseosalivarius based on 16S rRNA analysis and ARDRA patterns
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Abstract
S. Buczolits, EBM. Denner, D. Vybiral, M. Wieser, P. Kampfer and H. J. Busse
Institut fur Bakteriologie, Mykologie und Hygiene, Veterinarmedizinische Universitat, Veterinarplatz 1, A-1210 Wien, Austria
Three aerobic, Gram-negative, rod-shaped, non-spore-forming, red-pigmented, airborne bacteria (I/26-Cor1(T), I/32A-Cor1 and I/74-Cor2) collected in the Museo Correr (Venice, Italy) were investigated to determine their taxonomic status by analysing their biochemical, physiological and chemotaxonomic features and the G+C content of genomic DNA and by comparing their genomic fingerprints. Additionally, the almost complete 16S rRNA gene sequence of strain I/26-Cor1(T) was analysed. The three strains were nearly identical in their morphological, physiological, biochemical and chemotaxonomic properties. The strains contained a menaquinone system with the predominant menaquinone MK-7 and a fatty acid profile with C15:0 anteiso, C15:0 iso and C16:1 predominant. Phosphatidylethanolamine and several unidentified lipids were detected in the polar lipid profiles. The polyamine pattern consisted of sym-homospermidine as the major compound. meso-Diaminopimelic acid was found as the characteristic cell-wall diamino acid. The DNA base composition of the three strains ranged from 60 to 63 mol% G+C. Phylogenetically, strain I/26-Cor1(T) was most closely related to Hymenobacter actinosclerus (95.8% 16S rRNA gene sequence similarity). Physiological and genomic characteristics indicated that the two strains I/26-Cor1(T) and I/32A-Cor1 are representatives of the same species. The phylogenetic distance to any validly described taxon as indicated by 16S rRNA gene sequence similarities demonstrates that I/26-Cor1(T) and I/32A-Cor1 represent a novel species, for which the name Hymenobacter aerophilus sp. nov. is proposed, with the type strain I/26-Cor1(T) (=DSM 13606(T)=LMG 19657(T)). I/32A-Cor1 (=DSM 13607=LMG 19658) is another strain of the species Hymenobacter aerophilus. Since the taxonomic status of strain I/74-Cor2 within the genus Hymenobacter was not determined unambiguously, it is designated Hymenobacter sp. I/74-Cor2 (=DSM 13611=LMG 19659).