ORIGINAL PAPER Nocardia casuarinae sp. nov., an actinobacterial endophyte isolated from root nodules of Casuarina glauca Faten Ghodhbane-Gtari • Imen Nouioui • Karima Salem • Amir Ktari • Maria del Carmen Montero-Calasanz • Louis S. Tisa • Hans-Peter Klenk • Maher Gtari Received: 19 December 2013 / Accepted: 30 March 2014 Ó Springer International Publishing Switzerland 2014 Abstract An actinobacterium strain BMG51109a was isolated from surface sterilized root nodules of Casuarina glauca collected in Tunisia. The 16S rRNA gene sequence of strain BMG51109a showed most similarity (96.53–96.55 %) to the type strains of Nocardia transvalensis, N. aobensis and N. elegans. Chemotaxonomic analysis supported the assignment of the strain to Nocardia genus. The major menaquin- one was MK-8(H 4 c) while the polar lipid profile contained diphosphatidylglycerol, phosphatidylmono- methylethanolamine, glycophospholipid, phosphati- dylinositol, one uncharacterized phospholipid and three glycolipids. Whole-cell sugar analysis revealed the presence of meso-diaminopimelic acid, arabinose and galactose as diagnostic sugars, complemented by glucose, mannose and ribose. The major cellular fatty acids were tuberculostearic, oleic, palmitoleic and stearic acids. Physiological and biochemical tests showed that strain BMG51109a could be clearly distinguished from its closest phylogenetic neigh- bours. On the basis of these results, strain BMG51109a T (= DSM 45978 T = CECT 8469 T ) is proposed as the type strain of the novel species Nocardia casuarinae sp. nov. Keywords Nocardia casuarinae Á Casuarina Á Root nodule Á Sp. nov Introduction The Nocardia genus contains more than 75 validly named species described mostly during the last decade through a combination of genotypic and phenotypic clustering (Goodfellow and Maldonado 2010). Nocar- dia strains are best known as pathogen agents of suppurative and granulomatous diseases in humans and animals, particularly mycetoma and nocardiosis (Beaman and Beaman 1994; Boiron et al. 1993; Brown-Elliott et al. 2006; Goodfellow 1998; McNeil and Brown 1994). Several strains have been isolated from soils, cave, sand, river banks (Goodfellow and Maldonado 2010). Some strains of the genus Nocardia are biotechnologically important thanks to their inter- esting secondary metabolites such as amicoumacin B, (Sun et al. 2009), nocardicins (Aoki et al. 1976; F. Ghodhbane-Gtari Á I. Nouioui Á K. Salem Á A. Ktari Á M. Gtari (&) Laboratoire Microorganismes et Biomole ´cules Actives, Universite ´ Tunis El Manar (FST) & Universite ´ Carthage (INSAT), Campus Universitaire, 2092 Tunis, Tunisia e-mail: maher.gtari@fst.rnu.tn M. C. Montero-Calasanz Á H.-P. Klenk Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Brunswick, Germany L. S. Tisa Department of Molecular, Cellular, & Biomedical Sciences, University of New Hampshire, Durham, NH, USA 123 Antonie van Leeuwenhoek DOI 10.1007/s10482-014-0168-6