Identification of brazilian aspergilli based on a polyphasic approach including MALDI-TOF ICMS

Abstract

Microbial culture collections were established to preserve cultures of fungi and bacteria for taxonomical studies. However, nowadays they are also important for the ex situ conservation of microbial biodiversity. They are responsible for collecting, cataloguing, identifying and preserving strains for biomedical research, teaching, industry, agriculture, etc. Hence, this current work performed a polyphasic study based on morphology, biochemistry and MALDI-TOF ICMS to identify aspergilli from different environments in Brazil. Thirteen isolates of Aspergillus spp. deposited at the Filamentous Fungi Collection of Ribeirão Preto (CFF-RP) were analysed. Strains were grown on Czapek-Dox Agar (CZA) and Malt Extract Agar (MEA) at 30°C for morphology. Biochemical characterisation (production of ochratoxin A and fumonisin B2) was performed by HPLC. The MALDI-TOF ICMS analysis were performed on an Axima LNR system (Kratos Analytical, Shimadzu, Manchester, UK) equipped with a nitrogen laser (337 nm), using a mass range from m/z=2000 to 20000 Da and Escherichia coli DH5α strain for external calibration. The fungal identifications were performed using SARAMIS software (AnagnosTech mbH, Postdam-Golm, Germany). One A. thermomutatus was an OTA producer. In contrast, fumonisin B2 was no detected for all strains studied. The MALDI-TOF ICMS results corroborated the morphological identifications. Of the 13 isolates, 38, 31, 15.5 and 15.5% were A. fumigates, A. niveus, A. thermomutatus and A. ochraceus, respectively. These results contribute to knowledge about microbial biodiversity from the Brazilian environment.