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Research Article

Pseudonocardia benzenivorans sp. nov.

Kampfer, Peter, Kroppenstedt, Reiner M.

International Journal of Systematic and Evolutionary Microbiology 2004; 54(3):749 · https://doi.org/10.1099/ijs.0.02825-0

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Summary auto-generated

This study describes the identification and characterization of a novel bacterial species, Pseudonocardia benzenivorans, isolated from soil contaminated with chlorinated aromatic compounds in Germany. Strain B5T was recovered from an enrichment culture using 1,2,3,5-tetrachlorobenzene as the sole carbon source. The bacterium is gram-positive, rod-shaped, and non-spore-forming, with beige vegetative mycelium and white aerial mycelium. Phylogenetic analysis based on 16S rRNA gene sequences showed closest relationships to Pseudonocardia sulfidoxydans (98.8% similarity) and Pseudonocardia hydrocarbonoxydans (98.3% similarity). Chemotaxonomic analysis confirmed genus affiliation through characteristic menaquinone MK-8(H4), polar lipids including diphosphatidylglycerol and phosphatidylethanolamine, and specific fatty acid profiles. DNA-DNA hybridization experiments demonstrated low similarity values (38% and 23% respectively) to the two closest relatives, supporting species distinction. Physiological and biochemical tests further differentiated strain B5T from related species. The authors propose the formal designation Pseudonocardia benzenivorans sp. nov. with type strain B5T, expanding the genus Pseudonocardia to include this chlorinated-benzene-degrading organism.

Key findings

  • Pseudonocardia benzenivorans is a novel gram-positive, rod-shaped actinomycete isolated from chlorinated-benzene contaminated soil and capable of utilizing 1,2,3,5-tetrachlorobenzene as sole carbon source
  • 16S rRNA gene analysis shows the strain is most closely related to P. sulfidoxydans and P. hydrocarbonoxydans, but DNA-DNA hybridization values (38% and 23%) confirm it represents a distinct species
  • Chemotaxonomic characterization including menaquinone MK-8(H4), polar lipids, and fatty acid profiles supports classification within the genus Pseudonocardia
  • Physiological and biochemical tests differentiate P. benzenivorans from related Pseudonocardia species through differential substrate utilization and enzyme activity patterns

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Abstract

A Gram-positive, rod-shaped, non-spore-forming bacterium (B5T) was isolated from an enrichment culture that contained 1,2,3,5-tetrachlorobenzene as the sole source of carbon. On the basis of 16S rRNA gene sequence similarity studies, strain B5T was shown to belong to the family Pseudonocardiaceae and was related most closely to Pseudonocardia sulfidoxydans (98·8 %) and Pseudonocardia hydrocarbonoxydans (98·3 %). 16S rRNA gene sequence similarity to other Pseudonocardia species was <97 %. Chemotaxonomic data [major menaquinone, MK-8(H4); major polar lipids, diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol; major fatty acids, C16 : 0, iso-C16 : 0 and iso-C15 : 0] supported the affiliation of strain B5T to the genus Pseudonocardia. The results of DNADNA hybridizations and physiological and biochemical tests allowed genotypic and phenotypic differentiation of strain B5T from P. sulfidoxydans and P. hydrocarbonoxydans. Strain B5T therefore represents a novel species of the genus Pseudonocardia, for which the name Pseudonocardia benzenivorans sp. nov. is proposed, with the type strain B5T (=DSM 44703T=CIP 107928T).