Actinomyces naturae sp. nov., the first Actinomyces sp. isolated from a non-human or animal source

Abstract

Three facultatively anaerobic, Gram-positive staining, rod-shaped, non-spore forming, flagellated bacterial strains, BL-75, BL-79(T) and BL-104, were isolated from chlorinated solvent-contaminated groundwater. Phylogenetic analysis based on 16S rRNA gene sequence comparisons showed them to represent a distinct lineage within the genus Actinomyces with sequence identities in the range of <88-95.4% with previously described Actinomyces species. The strains were oxidase and catalase negative. Nitrate was not reduced. Esculin was hydrolyzed. Growth occurred in the temperature range of 20-43°C (optimum 30-37°C) and pH range 4.5-9.0 (optimum pH 6.5). Substrates supporting growth included various mono-, di-, and tri-saccharides. The end products of glucose fermentation were acetate, lactate, succinate and formate. Fermentative growth was observed in the presence of near saturation concentrations of perchloroethene (PCE) and toluene and in the presence of 1,2-dichloroethane and 1,1,2-trichloroethane at concentrations up to at least 24.4 mM and 11.2 mM, respectively. The dominant cellular fatty acids when grown in peptone/yeast extract/glucose (PYG) medium were C(18:1) ω9c, C(16:0), and C(14:0). The peptidoglycan was found to contain the amino acids alanine, glutamic acid, lysine, and ornithine at approximate molar ratios of 1.7 Ala: 2.3 Glu: 1.3 Lys: 1.0 Orn. The cell wall sugars were found to include rhamnose and mannose. The polar lipids were found to include diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phospholipid (PL), phosphoglycolipids (PGL), and glycolipids (GL). The main respiratory quinone of strain BL-79(T) was MK-9(H(4)), with minor components MK-10(H(4)) and MK-8(H(4)). The DNA mol% G+C content of the type strain is 69.8%. On the basis of phylogenetic and phenotypic characteristics, these strains could be differentiated from previously described species of the genus Actinomyces. Strains BL-75, BL-79(T) and BL-104 are designated as a novel species, for which the name Actinomyces naturae sp. nov. is proposed. This is the first Actinomyces species isolated from an environmental rather than human or animal sources. The type strain of Actinomyces naturae is BL-79(T) (= CCUG 56698(T) = NRRL B-24670(T)).

Actinomyces and Related Organisms in Human Infections

“…Rao et al (26), however, isolated Actinomyces naturae from chlorinated solvent-contaminated groundwater. The optimal temperature for growth of this species, 30°C to 37°C, suggests that the primary source may have been an animal.…”

Actinomyces Species Isolated from Breast Infections

“…Humans and animals are the natural reservoirs of Actinomyces species, which until recently have not been found to exist freely in nature (29). Their normal habitat is the mucosal membranes of the oropharynx, gastrointestinal tract, and female genital tract.…”

Nocardia and Actinomyces

“…Classification traditionally relied on morphological and biochemical characteristics of the species but it resulted in misidentification, so a classification based on genotypic methods, including 16S ribosomal RNA and DNA probe analysis, has been useful in definitive identification [140]. Most Actinomyces seem to occur primarily as a normal inhabitant of the mucous membranes of humans and animals, especially of the oral cavity and gastrointestinal tract [138], although one species was isolated from chlorinated solvent-contaminated groundwater [141]. Actinomyces spp.…”