Screening of Sonoran desert fungal strains for feruloyl esterase activity
During last two decades, feruloyl esterases have been intensely studied for industrial or medical applications. Also screening of microbes from thermal and extreme environments as source of this kind of enzymes with improved properties is an active research field. In this context, screening and selection of fungal strains, for feruloyl esterase activity, were developed at Sonoran Desert, one of the hottest and driest regions of America. Sampling was carried out from soil and plant residues decomposing on soil. Samples were suspended in water, diluted, spread onto agar and cultured at 40 °C. Isolated strains were spread onto selective agar, choosing those with feruloyl esterase hydrolytic halo/colony diameters ratio>2. Selected strains were identified by molecular methods and their secretomes were assessed for methyl hydroxy cinnamates specificity. Twenty thermotolerant fungal strains, showing high feruloyl esterase activity, were found and identified as Aspergillus flavus (2), Aspergillus fumigatus (2), Aspergillus tamarii (2), Aspergillus terreus (11), Neurospora tetrasperma (1) and Phialophora alba (2). At least 10 of those shown 2.5 to 3.8 higher feruloyl esterase activities, than Aspergillus terreus ATCC1012, a mesophile strain. Secretomes exposed scarce specificity for substrates. Selected feruloyl esterases-producing strains show high potential to be used as biotechnological tools.
Bácame-Valenzuela, F.J., J.A. Rodríguez, J.C. Mateos-Díaz, M. Kirchmayr, E. Valenzuela-Soto, Y. Reyes-Vidal, M. Esqueda, A. Asaff
Journal of Pure and Applied Microbiology 9 (Spl. Edn. 1):131-138