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

• Main Authors: Atef Jaouani, Mohamed Neifar, Valeria Prigione, Amani Ayari, Imed Sbissi, Sonia Ben Amor, Seifeddine Ben Tekaya, Giovanna Cristina Varese, Ameur Cherif, Maher Gtari
• Format: Article
• Language: English
• Published: Hindawi Limited 2014-01-01
• Series: BioMed Research International
• Online Access: http://dx.doi.org/10.1155/2014/439197

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 β-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 (n=3), Alternaria (n=4), Aspergillus (n=3), Penicillium (n=5), Ulocladium (n=2), and Engyodontium (n=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.