Proposal of a type strain for Frankia alni (Woronin 1866) Von Tubeuf 1895, emended description of Frankia alni, and recognition of Frankia casuarinae sp. nov. and Frankia elaeagni sp. nov.
Before the establishment of pure cultures, the species Frankia alni, 'Frankia casuarinae' and 'Frankia elaeagni' were proposed to encompass all causal agents of the nitrogen-fixing root nodules of dicotyledonous plants from the genera Alnus, Casuarina or Elaeagnus. The sole Frankia species with a validly published name, the type species F. alni, was described by Woronin (1866) as present in the root of alder. Until now no type strain has been designated for F. alni, even though the absence of a type strain has seriously inhibited the application of modern taxonomic methods to the genus Frankia. Thus, we propose that strain ACN14aT, isolated in pure culture from Alnus viridis ssp. crispa with morphological properties matching the original description of F. alni, be recognized as the type strain of this species according to Rule 18f of the International Code of Nomenclature of Bacteria. We compared ACN14aT to two strains, CcI3T and BMG5.12T, isolated from Casuarina cunninghamiana and Elaeagnus angustifolia, respectively, based on chemotaxonomy, phenotype microarray data and molecular data retrieved from genome sequences. All three tested strains grew as branched hyphae, produced vesicles and multilocular sporangia containing non-motile spores and metabolized short fatty acids, TCA-cycle intermediates and carbohydrates. Chemotaxonomically, the three strains were indistinguishable with respect to phospholipids (phosphatidylinositol, diphosphatidylglycerol, glycophospholipids and phosphatidylglycerol) and cell-sugar composition (glucose, mannose, ribose, rhamnose, galactose and xylose, with the latter two being diagnostic for the genus). The major fatty acids identified in all three strains were iso-C16 : 0, C17 : 1ω8c, C15 : 0, C17 : 0 and C16 : 0. ACN14aT and BMG5.12T also shared C15 : 1ω6c, while C18 : 1ω9c was found to be unique to BMG5.12T. The major menaquinones identified in all three novel type strains were MK-9(H8), MK-9(H6) and MK-9(H4). MK-9(H2) was shared by ACN14aT and BMG5.12T, while MK-10(H4) and MK-8(H4) were only found in BMG5.12T. Analysis of 16S rRNA gene sequences showed 98.1-98.9 % identity between strains ACN14aT, CcI3T and BMG5.12T. Digital DNA-DNA hybridization values between the three type strains were well below 70 %. These results confirm the separation of the strains into three distinct species, Frankia alni, Frankia casuarinae sp. nov. and Frankia elaeagni sp. nov. Thus, we propose ACN14aT (=DSM 45986T=CECT 9034T), CcI3T (=DSM 45818T=CECT 9043T) and BMG5.12T (=DSM 46783T=CECT 9031T) as the respective type strains.
Laboratoire Microorganismes et Biomolécules Actives, Université Tunis El Manar (FST) & Université de Carthage (INSAT), 2092 Tunis, Tunisia.|School of Biology, Newcastle University, Ridley Building 2, Newcastle upon Tyne, NE1 7RU, UK.
Imen
I
Nouioui
Laboratoire Microorganismes et Biomolécules Actives, Université Tunis El Manar (FST) & Université de Carthage (INSAT), 2092 Tunis, Tunisia.
Faten
F
Ghodhbane-Gtari
School of Biology, Newcastle University, Ridley Building 2, Newcastle upon Tyne, NE1 7RU, UK.
Maria Del Carmen
MDC
Montero-Calasanz
Leibniz Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Inhoffenstraße 7B, 38124 Braunschweig, Germany.
Markus
M
Göker
Leibniz Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Inhoffenstraße 7B, 38124 Braunschweig, Germany.
Jan P
JP
Meier-Kolthoff
Leibniz Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Inhoffenstraße 7B, 38124 Braunschweig, Germany.
Peter
P
Schumann
Central Facility for Microscopy, HZI - Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany.
Manfred
M
Rohde
School of Biology, Newcastle University, Ridley Building 2, Newcastle upon Tyne, NE1 7RU, UK.
Michael
M
Goodfellow
Ecologie Microbienne, Centre National de la Recherche Scientifique UMR 5557, Université de Lyon, Université Claude Bernard Lyon I, INRA, UMRA1418, Cedex, 69622 Villeurbanne Cedex, France.
Maria P
MP
Fernandez
Ecologie Microbienne, Centre National de la Recherche Scientifique UMR 5557, Université de Lyon, Université Claude Bernard Lyon I, INRA, UMRA1418, Cedex, 69622 Villeurbanne Cedex, France.
Philippe
P
Normand
Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, 289 Rudman Hall, 46 college Road, Durham, NH 03824-2617, USA.
Louis S
LS
Tisa
School of Biology, Newcastle University, Ridley Building 2, Newcastle upon Tyne, NE1 7RU, UK.
Hans-Peter
HP
Klenk
Laboratoire Microorganismes et Biomolécules Actives, Université Tunis El Manar (FST) & Université de Carthage (INSAT), 2092 Tunis, Tunisia.
Maher
M
Gtari
D015373:Bacterial Typing Techniques; D001482:Base Composition; D004269:DNA, Bacterial / Q000235:genetics; D005227:Fatty Acids / Q000737:chemistry; D040161:Frankia / Q000145:classification*; D009693:Nucleic Acid Hybridization; D010743:Phospholipids / Q000737:chemistry; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D024482:Vitamin K 2 / Q000737:chemistry
D004269:DNA, Bacterial; D005227:Fatty Acids; D010743:Phospholipids; D012336:RNA, Ribosomal, 16S; D024482:Vitamin K 2