The goal of the present work was to determine the diversity of prokaryotes involved in anaerobic oil degradation in oil fields. The composition of the anaerobic oil-degrading methanogenic enrichment obtained from an oil reservoir was determined by 16S rRNA-based survey, and the facultatively anaerobic chemoorganotrophic bacterial strain HO-Ch2^T was isolated and studied using polyphasic taxonomy approach and genome sequencing. The strain HO-Ch2^T grew optimally at 28 °C, pH 8.0, and 1–2% (w/v) NaCl. The 16S rRNA gene sequence of the strain HO-Ch2^T had 98.8% similarity with the sequence of Actinotalea ferrariae CF5-4^T. The genomic DNA G + C content of strain HO-Ch2^T was 73.4%. The average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values between the genome of strain HO-Ch2^T and Actinotalea genomes were 79.8–82.0% and 20.5–22.2%, respectively, i.e., below the thresholds for species delineation. Based on the phylogenomic, phenotypic, and chemotaxonomic characterization, we propose strain HO-Ch2^T (= VKM Ac-2850^T = KCTC 49656^T) as the type strain of a new species within the genus Actinotalea, with the name Actinotalea subterranea sp. nov. Based on the phylogenomic analysis of 187 genomes of Actinobacteria we propose the taxonomic revision of the genera Actinotalea and Pseudactinotalea and of the family Actinotaleaceae. We also propose the reclassification of Cellulomonas carbonis as Actinotalea carbonis comb. nov., Cellulomonas bogoriensis as Actinotalea bogoriensis comb. nov., Actinotalea caeni as Pseudactinotalea caeni comb. nov., and the transfer of the genus Pseudactinotalea to the family Ruaniaceae of the order Ruaniales.

The composition and structure of the cell wall glycopolymers of Paenarthrobacter species (P. aurescens VKM Ac-1105^T, P. histidinovorans VKM Ac-1978^T, and P. nicotinovorans VKM Ac-1988^T, previously assigned to the genus Arthrobacter) were studied. All strains under study were found to contain a neutral polysaccharide, (1 → 6)-linked β-D-galactofuranan with the 2,3-diacetamido-2,3-dideoxy-α-glucopyranose (α-GlcpNAc3NAc) residues that glycosylate most of the hydroxyl groups at C-2 of galactofuranose. Acid hydrolysates of the cell walls contained galactose, glucose, arabinose, glucosamine, and galactosamine. The polysaccharide structure was established by chemical and NMR spectroscopic methods. The galactofuranan structure has not been previously described for representatives of other Actinobacteria genera. The data obtained expand our understanding of the chemical structure of microbial cell walls and may be used in taxonomy of actinobacteria, especially to differentiate at the phenotype level and to justify the description of new genera in the family Micrococcaceae.

Presence of the cell wall glycopolymer rhamnan was established for members of the genus Curtobacterium (family Microbacteriaceae) by using chemical and NMR spectroscopic methods. The rhamnan with the repeating unit, →2)-α-L-Rhap-(1→3)-α-L-Rhap-(1→, was found in C. flaccumfaciens pv. flaccumfaciens VKM Ас-1923^T, C. flaccumfaciens pv. poinsettiae VKM Ас-1924^T, C. pusillum VKM Ac-2099^T, C. herbarum VKM Ac-2512^T, and Curtobacterium sp. VKM Ac-1811. Each of the studied strains also contained a second, acidic phosphate-free polysaccharide. NMR spectra of these polysaccharides differed, indicating the structural differences. Cell wall hydrolysates of all studied strains were found to contain rhamnose, mannose, glucose, galactose, and glucosamine. Further research will facilitate more detailed characterization of the composition of cell wall glycopolymers in Curtobacterium species, as well as evaluation of their taxonomic significance. The data on the polymer structure will contribute to understanding of the mechanisms of colonization and infection of higher organisms by Curtobacterium species and bacterial interaction in microbial communities and with abiotic environmental objects.

A hexasaccharide 1-phosphate polymer of original structure and two teichoic acids (TA) belonging to different structural types were found in Arthrobacter uratoxydans VKM Ac-1979^T cell wall. The poly(hexasaccharide 1-phosphate) combines features of teichuronic acids and glycosyl 1-phosphate polymers, and its structure has never been reported earlier. Its composition includes residues of α- and β-D-glucuronic acid as well as α-D-galacto-, β-D-gluco-, α-D-mannopyranose, and 6-O-acetylated 2-acetamido-2-deoxy-α-D-glucopyranose. The phosphodiester bond in the polymer joins the glycoside hydroxyl of α-D-glucuronic acid and O6 of α-D-galactopyranose. TA 1 is β-D-glucosylated 1,3-poly(glycerol phosphate), and TA 2 is 3,6-linked poly[α-D-glucosyl-(1→2)-glycerol phosphate]. The phosphate-containing polymers were studied by chemical methods and on the basis of one-dimensional ¹H-, ¹³C-, and ³¹P-NMR spectra, homonuclear two-dimensional ¹H/¹H COSY, TOCSY, ROESY, and heteronuclear ¹H/¹³C HSQC, HSQC-TOCSY, HMBC, and ¹H/³¹P HMBC experiments. The set and structure of the polymers revealed as well as the cell wall sugars (galactose, glucose, mannose, glucosamine) and glycerol can be used in microbiological practice for taxonomic purposes.