Tolérance a la salinité et activité solubilisatrice du phosphore dicalcique des endophytes fongique d’origine algale

Abstract

A new, more sustainable agricultural system must be developed to increase production without compromising human and animal health ; and the preservation of essential resources, such as soil, water and diversity. Filamentous endophytic fungi, whether used individually, in combination with each other or with other microorganisms, contribute significantly to the promotion of plant growth and to the mitigation of various biotic and abiotic stresses. Thus, the present study focuses on endophytic fungi carrying features linked to the support of plant growth in saline environments. Six endophytic isolates including Aspergillus niger, Aspergillus sp. Penicillium sp., Scopulariopsis sp. and Gliocladium (plus an unidentified isolate) were isolated from marine algae collected from the coastal area of Stidia, in the Mostaganem region. The salinity tolerance of endophytes was studied. To do this, their colonies, grown on PDA medium, were exposed to different concentrations of NaCl ranging from 50 to 425 mM. Depending on the isolate, the endophytes showed good growth and high sporulation capacity in the presence of high concentrations of NaCl up to 425mM. These isolates were then tested in vitro for one of the important traits specific to promoting plant growth, namely phosphorus solubilization. Among the isolates tested, three showed solubilization efficiency by the screening test on solid medium (Aspergillus niger, Penicillium sp. and Gliocladium sp.). The latter were selected to test their ability to solubilize phosphorus, in vitro, in a liquid medium. They then showed an excellent solubilizing power of dicalcium phosphorus.