Diversity of Filamentous Fungi of Area from Brazilian Caatinga and High-Level Tannase Production Using Mango (Mangifera indica L.) and Surinam Cherry (Eugenia uniflora L.) Leaves under SSF

Tannase is a biotechnologically important enzyme that can be produced during fungal fermentation of organic matter. The Caatinga is an exclusive Brazilian ecosystem that has been largely unexplored by science, particularly its filamentous fungal diversity. This study evaluated the diversity of filamentous fungi in the Caatinga soils of Pernambuco, Brazil, and their potential for tannase production by solid-state fermentation (SSF) of mango (Mangifera indica L.) and Surinam cherry (Eugenia uniflora L.) leaves. A total of 4711 isolates were obtained, 2090 during the rainy seasonand 2621 during the dry season. The isolates belonged to 18 genera and 66 species, with Aspergillus and Penicillium having the highest species richness. The dry season had a higher diversity index. Aspergillus was the dominant genus, and A. flavus, A. sclerotiorum, and A. ochraceus the most abundant species. A representative of each species was tested for tannase production using dried mango and Surinam cherry leaves as substrates; the leaves contained 14.28 and 7.0 g/L tannin, respectively. Most fungal species produced tannase, but the highest yields were obtained when mango leaves were used as substrate for Penicillium restrictum (accession URM 6044), Aspergillus flavofurcatus (URM 6142), and A. stromatoides (URM 6609), which produced 104.16, 87.51, and 81.83 U/mL tannase, respectively. These yields exceeded previously published reports. Filamentous fungi from Caatinga soils have great potential for producing tannase by SSF, and low-cost mango leaves make excellent substrate.