SECONDARY METABOLITE PROFILING OF FOOD-BORNE ALTERNARIA

DA CRUZ CABRAL, LUCÍA; FOG NIELSEN, KRISTIAN; ANDERSEN, BIRGITTE; PAVICICH, MARÍA AGUSTINA; PATRIARCA, ANDREA

Ghent

Congreso; First Mycokey International Conference; 2017

H2020

SECONDARY METABOLITE PROFILING OF FOOD-BORNE ALTERNARIALucía da Cruz Cabral1, María Agustina Pavicich1, Birgitte Andersen2, Kristian Fog Nielsen2 and Andrea Patriarca1*1 Laboratorio de Microbiología de Alimentos/Departamento de Química Orgánica/Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires/Buenos Aires, Argentina2 Section for Microbial ecology and physiology/DTU Bioengineering/Technical University of Denmark/Kgs. Lyngby, Denmark* Corresponding author: andreap@qo.fcen.uba.ar The genus Alternaria includes both plant pathogenic and saprophytic species, which can affect crops in the field or cause post-harvest spoilage of plant fruits and kernels. Alternaria species have the ability to produce a wide variety of secondary metabolites, which play important roles in food safety. Alternariol (AOH), alternariol monomethylether (AME), tenuazonic acid (TA), altenuene (ALT), tentoxin (TEN) and altertoxins (ATXs) are the main compounds thought to pose a risk to human health. However, food-borne Alternaria species are able to produce many more metabolites, whose toxicity has been tested incompletely or not tested at all. To understand the full chemical potential of food associated Alternaria spp., and their distribution on crops and food products, the secondary metabolite profiles of Alternaria strains isolated from food substrates were analysed.A total of 360 strains isolated from tomato (107), pepper (64), wheat (94), blueberry (44), apple (45), and walnut (6) were analysed. The morphological characterization was made according to Simmons (2007), based on the three-dimensional sporulation pattern, microscopic morphology, and colony characteristics. The metabolite profiling was done on DRYES (14 days, 25°C) by micro-extraction with ethyl acetate-1% formic acid (Andersen et al., 2015). Detection was performed by UHPLC-HRMS. MS was performed in ESI+ and ESI- in the scan range m/z 100?1000, with a mass accuracy < 1.5 ppm. Data processing involved an aggressive dereplication approach, matching Alternaria and related genera compounds with data based on accurate mass and isotopic pattern, and UV/Vis data. MS/HRMS were further conducted for matching fragmentations with the molecular structure. Through morphological identification the strains were classified into the species-groups (sp.-grp.) A. alternata (7), A. arborescens (39), A. tenuissima (261), and A. infectoria (19). The remaining 34 strains could not be assigned to a specific sp.-grp. and were referred to as Alternaria sp. All sp.-grp. were distributed among the different food products except for A. infectoria, which was only isolated from wheat. A total of 45 known secondary metabolites produced by Alternaria spp. from food were detected. Additionally, 44 compounds of unknown structure were produced by these strains. The metabolite profiles overlapped among the food species, except for strains belonging to the A. infectoria sp.-grp., which had no metabolites in common with the other strains. AOH and AME were the compounds produced by most of the strains (283 and 285, respectively), followed by Pyrenochaetic acid A (269), ALT (248), Altechromone A (247), TEN (224), TA (209) and its isopropyl derivative (186), ATX-I (159), and Altersetin (145). More than 100 strains were also able to produce alterperylenol, 3-Hydroxyalternariol 5-O-methyl ether, ATX-II, altenuisol, altenusin, and dihydrotentoxin. These metabolites were produced by strains from all food products analysed. Toxicological data on these compounds would be necessary to design regulatory guidelines on Alternaria metabolites in food products.