Diversity and Enzymatic Profiling of Halotolerant Micromycetes from Sebkha El Melah, a Saharan Salt Flat in Southern Tunisia

Twenty-one moderately halotolerant fungi have been isolated from sample ashes collected from Sebkha El Melah, a Saharan salt flat located in southern Tunisia. Based on morphology and sequence inference from the internal transcribed spacer regions, 28S rRNA gene and other specific genes such as -tubulin, actin, calmodulin, and glyceraldehyde-3-phosphate dehydrogenase, the isolates were found to be distributed over 15 taxa belonging to 6 genera of Ascomycetes: Cladosporium ( = 3), Alternaria ( = ∘4), Aspergillus ( = 3), Penicillium ( = 5), Ulocladium ( = 2), and Engyodontium ( = 2). Their tolerance to different concentrations of salt in solid and liquid media was examined. Excepting Cladosporium cladosporioides JA18, all isolates were considered as alkali- halotolerant since they were able to grow in media containing 10% of salt with an initial pH 10. All isolates were resistant to oxidative stresses and low temperature whereas 5 strains belonging to Alternaria, Ulocladium, and Aspergillus genera were able to grow at 45 C. The screening of fungal strains for sets of enzyme production, namely, cellulase (CMCase), amylase, protease, lipase, and laccase, in presence of 10% NaCl, showed a variety of extracellular hydrolytic and oxidative profiles. Protease was the most abundant enzyme produced whereas laccase producers were members of the genus Cladosporium.