title: The Tunisian oasis ecosystem is a source of antagonistic Bacillus spp. producing diverse antifungal lipopeptides.
abstract: The use of microbial products has become a promising alternative approach to controlling plant diseases caused by phytopathogenic fungi. Bacteria isolated from the date palm tree rhizosphere of the Tunisian oasis ecosystem could provide new biocontrol microorganisms adapted to extreme conditions, such as drought, salinity and high temperature. The aim of this study was to screen bacteria isolated from the rhizosphere of the date palm tree for their ability to inhibit phytopathogenic fungi, and to identify molecules responsible for their antifungal activity. Screening for antifungal activity was performed on twenty-eight isolates. Five antagonistic isolates were selected and identified as different species of Bacillus using phenotypical methods and a molecular approach. The five antagonistic Bacillus isolated showed tolerance to abiotic stresses (high temperature, salinity, drought). Their ability to produce lipopeptides was investigated using a combination of two techniques: PCR amplification and MALDI-ToF mass spectrometry. Analyses revealed that the antagonistic isolates produced a high diversity of lipopeptides that belonged to surfactin, fengycin, iturin and kurstakin families. Their antagonistic activity, related to their capacity for producing diverse antifungal lipopeptides and their tolerance to abiotic stresses, highlighted Bacillus strains isolated from the rhizosphere of the date palm tree as potential biocontrol agents for combatting plant diseases in extreme environments.
authors.affiliation: Université Lille, Institut Charles Viollette, EA 7394, Avenue Paul Langevin, F-59655 Villeneuve d'Ascq, France; Faculté des Sciences de Sfax, Laboratoire de Biotechnologie Microbienne affilié au Laboratoire de Biotechnologies Végétales Appliquées à l'Amélioration des Cultures in vitro, B.P. 802, 3018 Sfax, Tunisia. Electronic address: amel_elarbi@yahoo.fr.
authors.forename: Amel
authors.initials: A
authors.lastname: El Arbi
authors.affiliation: Université Lille, Institut Charles Viollette, EA 7394, Avenue Paul Langevin, F-59655 Villeneuve d'Ascq, France. Electronic address: alice.rochex@polytech-lille.fr.
authors.forename: Alice
authors.initials: A
authors.lastname: Rochex
authors.affiliation: Université Lille, Institut Charles Viollette, EA 7394, Avenue Paul Langevin, F-59655 Villeneuve d'Ascq, France. Electronic address: gabrielle.chataigne@polytech-lille.fr.
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Chataigné
authors.affiliation: Université Lille, Institut Charles Viollette, EA 7394, Avenue Paul Langevin, F-59655 Villeneuve d'Ascq, France. Electronic address: max.bechet@univ-lille1.fr.
authors.forename: Max
authors.initials: M
authors.lastname: Béchet
authors.affiliation: Université Lille, Institut Charles Viollette, EA 7394, Avenue Paul Langevin, F-59655 Villeneuve d'Ascq, France. Electronic address: didier.lecouturier@univ-lille1.fr.
authors.forename: Didier
authors.initials: D
authors.lastname: Lecouturier
authors.affiliation: Université Lille, Institut Charles Viollette, EA 7394, Avenue Paul Langevin, F-59655 Villeneuve d'Ascq, France. Electronic address: segolone.arnauld@polytech-lille.fr.
authors.forename: Ségolène
authors.initials: S
authors.lastname: Arnauld
authors.affiliation: Faculté des Sciences de Sfax, Laboratoire de Biotechnologie Microbienne affilié au Laboratoire de Biotechnologies Végétales Appliquées à l'Amélioration des Cultures in vitro, B.P. 802, 3018 Sfax, Tunisia. Electronic address: Neji.Gharsallah@fss.rnu.tn.
authors.forename: Néji
authors.initials: N
authors.lastname: Gharsallah
authors.affiliation: Université Lille, Institut Charles Viollette, EA 7394, Avenue Paul Langevin, F-59655 Villeneuve d'Ascq, France. Electronic address: philippe.jacques@polytech-lille.fr.
authors.forename: Philippe
authors.initials: P
authors.lastname: Jacques
mesh_terms: D000898:Antibiosis; D000935:Antifungal Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D001407:Bacillus / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D017753:Ecosystem; D005658:Fungi / Q000187:drug effects / Q000254:growth & development; D005670:Fusarium / Q000187:drug effects; D055666:Lipopeptides / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism* / Q000494:pharmacology; D065749:Phoeniceae / Q000382:microbiology; D010935:Plant Diseases / Q000517:prevention & control; D058441:Rhizosphere; D012988:Soil Microbiology; D014416:Tunisia
chemical_list: D000935:Antifungal Agents; D055666:Lipopeptides
keywords: Antifungal lipopeptides; Bacillus; Biological control; Date palm rhizosphere; Oasis ecosystem