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Agromyces salentinus sp. nov. and Agromyces neolithicus sp. nov.

Jurado, Valme, Groth, Ingrid, Gonzalez, Juan M., Laiz, Leonila, Saiz-Jimenez, Cesareo

International Journal of Systematic and Evolutionary Microbiology 2005; 55(1):153 · https://doi.org/10.1099/ijs.0.63199-0

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Summary auto-generated

This study describes two novel bacterial species isolated from soil samples at Grotta dei Cervi, an underground cave in Italy. Using polyphasic taxonomy combining 16S rRNA gene sequencing, chemotaxonomic analysis, and DNA-DNA relatedness studies, researchers identified two distinct Gram-positive bacterial strains, designated 20-5T and 23-23T, as new species within the genus Agromyces. Both strains formed filamentous, branching hyphae that fragmented into rod-like cells. The two isolates differed substantially in phenotypic characteristics, DNA G+C content (72.3 and 65.3 mol%, respectively), menaquinone composition, and cell wall amino acids. 16S rRNA sequence analysis showed less than 96% similarity to known Agromyces species, well below the 97% threshold for species designation. DNA-DNA relatedness values between the new strains and previously described Agromyces species were approximately 20-50%, confirming their distinct taxonomic positions. The authors propose these represent two new species: Agromyces salentinus sp. nov. (strain 20-5T) and Agromyces neolithicus sp. nov. (strain 23-23T), with type strains deposited in international culture collections.

Key findings

  • Two novel Agromyces species, A. salentinus and A. neolithicus, were identified from cave soil using polyphasic taxonomy combining 16S rRNA sequencing, chemotaxonomic data, and DNA-DNA hybridization
  • The strains showed <96% 16S rRNA gene sequence similarity to known Agromyces species and DNA-DNA relatedness values of only 20-50% compared to closest relatives
  • A. salentinus (72.3 mol% G+C) and A. neolithicus (65.3 mol% G+C) differed significantly in DNA G+C content, menaquinone composition, cell wall amino acids, and multiple phenotypic traits
  • Both strains were Gram-positive, aerobic to microaerophilic filamentous bacteria forming branching hyphae that fragmented into rod-like cells, consistent with genus Agromyces characteristics

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Abstract

A polyphasic study was carried out to clarify the taxonomic position of two Gram-positive bacteria isolated from soil samples of the Grotta dei Cervi (Italy), a relatively unexplored hypogean environment. The strains, 20-5T and 23-23T, showed phenotypic and phylogenetic characteristics that were consistent with their classification in the genus Agromyces. 16S rRNA gene sequence comparisons revealed that the two strains formed distinct phyletic lines within the genus Agromyces. Based on 16S rRNA gene sequence similarity, chemotaxonomic data and the results of DNADNA relatedness studies, it is proposed that the two isolates represent two novel species of the genus Agromyces. Pronounced differences in a broad range of phenotypic characteristics and DNA G+C content distinguished the two strains from each other and from previously described species of the genus Agromyces. Two novel species are proposed: Agromyces salentinus sp. nov. (type strain, 20-5T=HKI 0320T=DSM 16198T=NCIMB 13990T) and Agromyces neolithicus sp. nov. (type strain, 23-23T=HKI 0321T=DSM 16197T=NCIMB 13989T).