Open AccessFrankia irregularis sp. nov., an actinobacterium unable to nodulate its original host, Casuarina equisetifolia, but effectively nodulates members of the actinorhizal Rhamnales
Author(s) -
Imen Nouioui,
Faten GhodhbaneGtari,
Manfred Rhode,
Vartul Sangal,
HansPeter Klenk,
Maher Gtari
Publication year - 2018
Publication title -
international journal of systematic and evolutionary microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 173
eISSN - 1466-5034
pISSN - 1466-5026
DOI - 10.1099/ijsem.0.002914
Subject(s) - frankia , biology , actinorhizal plant , botany , casuarina equisetifolia , microbiology and biotechnology , peptidoglycan , actinobacteria , symbiosis , sporangium , 16s ribosomal rna , root nodule , gene , bacteria , genetics , spore , cell wall
A red pigmented actinobacterium designated G2 T , forming extremely branched vegetative hyphae, vesicles and mutilocular sporangia, was isolated from Casuarina equisetifolia nodules. The strain failed to nodulate its original host plant but effectively nodulated members of actinorhizal Rhamnales. The taxonomic position of G2 T was determined using a polyphasic approach. The peptidoglycan of the strain contained meso-diaminopimelic acid as diagnostic diamino acid, galactose, glucose, mannose, rhamnose, ribose and xylose. The polar lipid pattern consisted of phosphatidylinositol (PI), diphosphatidylglycerol (DPG), glycophospholipids (GPL1-2), phosphatidylglycerol (PG), aminophospholipid (APL) and unknown lipids (L). The predominant menaquinones were MK-9 (H4) and MK-9 (H6) while the major fatty acids were iso-C16 : 0, C17 : 1ω8c and C15 : 0. The size of the genome of G2 T was 9.5 Mb and digital DNA G+C content was 70.9 %. The 16S rRNA gene showed 97.4-99.5 % sequence identity with the type strains of species of the genus Frankia. Digital DNA -DNA hybridisation (dDDH) values between G2 T and its nearest phylogenetic neighbours Frankia elaeagniand Frankia discariaewere below the threshold of 70 %. On the basis of these results, strain G2 T (=DSM 45899 T =CECT 9038 T ) is proposed to represent the type strain of a novel species Frankia irregularis sp. nov.