Description of Azoarcus nasutitermitis sp. nov. and Azoarcus rhizosphaerae sp. nov., two nitrogen-fixing species isolated from termite nest and rhizosphere of Ficus religiosa

Antonie Van Leeuwenhoek. 2020 Jul;113(7):933-946. doi: 10.1007/s10482-020-01401-w. Epub 2020 Mar 28.


A polyphasic taxonomic approach was used to characterise two presumably novel bacteria, designated strains CC-YHH838T and CC-YHH848T isolated from termite nest and rhizosphere of Ficus religiosa, respectively. These two nitrogen-fixing strains were observed to be Gram-staining-negative, aerobic rod, and colonies were yellowish in color. Growth of strains was observed at 20-37 °C, pH 7-8, and in the presence of 1-2% NaCl. Phylogenetic analyses based on 16S rRNA genes revealed a distinct taxonomic position attained by strain CC-YHH838T and CC-YHH848T associated with Thauera hydrothermalis (97.1% sequence identity), and formed a separate branch with Azoarcus indigens (95.4%), Aromatoleum aromaticum (96.2%), and lower sequence similarity to other species. The calculation of OrthoANI values pointed out strains CC-YHH838T and CC-YHH848T gave 78.9% and 79.8% compared to Thauera hydrothermalis, respectively. The major fatty acids (> 5%) were C16:0, C17:0 cyclo, C10:0 3-OH, C16:1ω7c/C16:1ω6c and C18:1ω7c/C18:1ω6c. The polar lipid profile comprised phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and unidentified aminophospholipid and phospholipids; the predominant polyamines were putrescine and spermidine. The predominant respiratory system was ubiquinone (Q-8) and the DNA G + C contents were 61.4 ± 0.1 mol% and 60.2 ± 1.3 mol%, respectively. Based on the phylogenetic and polyphasic comparisons, strains CC-YHH838T and CC-YHH848T are proposed to represent two novel species within the genus Azoarcus in the family Rhodocyclaceae, for which the name Azoarcus nasutitermitis sp. nov. (type strain CC-YHH838T = BCRC 81059T = JCM 32001T) and Azoarcus rhizosphaerae sp. nov. (type strain CC-YHH848T = BCRC 81060T = JCM 32002T) were proposed.

Keywords: Azoarcus nasutitermitis; Azoarcus rhizosphaerae; Polyphasic taxonomy; Rhizosphere; Rhodocyclaceae.

MeSH terms

  • Animals
  • Azoarcus / classification*
  • Azoarcus / genetics
  • Azoarcus / isolation & purification*
  • Azoarcus / physiology
  • Bacterial Typing Techniques
  • Base Composition
  • DNA, Bacterial / genetics
  • Fatty Acids / analysis
  • Ficus / microbiology*
  • Isoptera / microbiology*
  • Nitrogen
  • Nitrogen Fixation
  • Phospholipids / analysis
  • Phylogeny*
  • RNA, Ribosomal, 16S / genetics
  • Rhizosphere*
  • Rhodocyclaceae
  • Soil Microbiology*
  • Thauera
  • Whole Genome Sequencing


  • DNA, Bacterial
  • Fatty Acids
  • Phospholipids
  • RNA, Ribosomal, 16S
  • Nitrogen

Supplementary concepts

  • Aromatoleum aromaticum
  • Azoarcus indigens
  • Thauera hydrothermalis