ORIGINAL RESEARCH PAPER Antifungal activities of an endophytic Pseudomonas fluorescens strain Pf1TZ harbouring genes from pyoluteorin and phenazine clusters Olfa Kilani-Feki • Oussama Khiari • Ge ´rald Culioli • Annick Ortalo-Magne ´ • Nabil Zouari • Yves Blache • Samir Jaoua Received: 20 January 2010 / Accepted: 16 April 2010 / Published online: 11 May 2010 Ó Springer Science+Business Media B.V. 2010 Abstract Pseudomonas fluorescens Pf1TZ was inhibitory in vitro to a number of phytopathogenic fungi and could protect vine plantlets against Botrytis cinerea. Total protection was reached after 3 weeks of bacterial inoculation. The endophytism of Pf1TZ was confirmed by confocal microscopy using its inherent fluorescence. The molecular characterization of Pf1TZ indicated the presence of genes from clusters encoding pyoluteorin and phenazine. The chromatographic purification and LC-MS n analysis revealed that the most active one has a molecular mass of 504 Da. Keywords Antifungal activity Á Plant protection Á Phenazine Á Pseudomonas fluorescens Á Pyoluteorin Introduction Biological control is an alternative strategy to reduce the use of chemicals thus contributing to the environ- ment preservation. Biofungicides are produced by bacteria, fungi or yeasts. Antagonistic bacteria repre- sent a realistic alternative to prevent plant diseases. They may act by several mechanisms including antag- onism or antibiosis, competition, predation or hyper- parasitism and stimulation of the natural defence of plants. Several Pseudomonas strains have been studied for their antagonism and their ability to protect plants (Amein et al. 2008). They have several advantages namely their abundance in the rhizosphere, which represent 0.1–1% of rhizobacteria (Haas and Keel 2003), a great adaptation capacity to the nutrients present in their environment (Ghiglione et al. 2000) and the synthesis of several antagonistic molecules, such as 2,4-diacetylphloroglucinol, pyrrolnitrin, HCN, phenazine and pyoluteorin, which were the subject of detailed studies for their activities, production and action modes (Ayyadurai et al. 2006). Many Pseudo- monas strains, including P. fluorescens Pf5 (Nowak- Thompson et al. 1994) and Pseudomonas sp. M18 (Hu et al. 2005) produce bioactive molecules. Electronic supplementary material The online version of this article (doi:10.1007/s10529-010-0286-9) contains supplementary material, which is available to authorized users. O. Kilani-Feki Á O. Khiari Á N. Zouari Á S. Jaoua (&) Laboratory of Biopesticides, Centre of Biotechnology of Sfax, P.O. Box 1177, 3038, Sfax, Tunisia e-mail: samir.jaoua@cbs.rnrt.tn; samirjaoua@qu.edu.qa S. Jaoua Biological and Environmental Sciences Department, College of Arts and Sciences, Qatar University, P.O. Box 2713, Doha, Qatar G. Culioli Á A. Ortalo-Magne ´ Á Y. Blache Laboratoire MAPIEM (EA 4323), Universite ´ du Sud Toulon Var, 83957 La Garde Cedex, France 123 Biotechnol Lett (2010) 32:1279–1285 DOI 10.1007/s10529-010-0286-9