Quinolactacin A

Almond production in Portugal is of great importance for the economy of their main producing areas. However, the contamination of these nut fruits with fungi and mycotoxins poses a significant risk to food safety and security. This work intended to evaluate the influence of storage conditions on the microbial and mycotoxin stability and safety of almonds throughout long-term storage. Two almond varieties-Lauranne and Guara-were submitted to three different storage conditions, namely, 4°C with noncontrolled relative humidity (RH), 60% RH at 25°C, and 70% RH at 25°C, for a storage period of 9 months. Samples were collected after 0, 3, 6, and 9 months of storage and analyzed for microbial loads (aerobic mesophiles, yeasts, and molds), mold incidence and diversity, and mycotoxin contamination. In total, 26 species were identified belonging to 6 genera: Aspergillus, Cladosporium, Fusarium, Penicillium, Paecilomyces, and Talaromyces. For the variety Guara, mycotoxins related to Aspergillus sect. Flavi, such as aflatoxins, averufin, versicolorin C, and norsolorinic acid, were detected only after 9 months of storage at 70% and 60% RH. Penicillium mycotoxins, such as quinolactacin A and roquefortine C, were also detected. For the variety Lauranne, Penicillium mycotoxins were detected, such as citrinin, quinolactacins A and B, roquefortines C and D, cyclopenin, cyclopenol, penitrem A, viridicatin, and viridicatol. Mycotoxins related to Aspergillus, such as aspulvinone E, flavoglaucin, paspalin, asperglaucide, asperphenamate, cyclo(L-Pro-L-Tyr), and cyclo(L-Pro-L-Val), were also detected. PRACTICAL APPLICATION: (Optional, for JFS Research Articles ONLY) The quality of almonds depends on the storage period and the RH and temperature at which they are stored. Storage of almonds at 60% RH at 25°C is a good storage condition to maintain the stability and safety of nuts in terms of microbial and mycotoxin contaminations.

Fungi are a prospective resource of bioactive compounds, but conventional methods of drug discovery are not effective enough to fully explore their metabolic potential. This study aimed to develop an easily attainable method to elicit the metabolic potential of fungi using Aspergillus nidulans laeA as a transcription regulation tool. In this study, functional analysis of Aspergillus nidulans laeA (AnLaeA) and Aspergillus sp. Z5 laeA (Az5LaeA) was done in the fungus Aspergillus sp. Z5. Heterologous AnLaeA-and native Az5LaeA-overexpression exhibited similar phenotypic effects and caused an increase in production of a bioactive compound diorcinol in Aspergillus sp. Z5, which proved the conserved function of this global regulator. In particular, heteroexpression of AnLaeA showed a significant impact on the expression of velvet complex genes, diorcinol synthesis-related genes, and different transcription factors (TFs). Moreover, heteroexpression of AnLaeA influenced the whole genome gene expression of Aspergillus sp. Z5 and triggered the upregulation of many genes. Overall, these findings suggest that heteroexpression of AnLaeA in fungi serves as a simple and easy method to explore their metabolic potential. In relation to this, AnLaeA was overexpressed in the fungus Penicillium sp. LC1-4, which resulted in increased production of quinolactacin A.

The occurrence of secondary metabolites and co-contaminants in dairy cow feed samples (n = 115), concentrate, roughage, and mixed feed, collected from Ratchaburi and Kanjanaburi provinces, Thailand, between August 2018 and March 2019 were investigated using LC-MS/MS based multi-toxin method. A total of 113 metabolites were found in the samples. Fungal metabolites were the predominant compounds, followed by plant metabolites. Among major mycotoxins, zearalenone and fumonisins were most frequently detected in concentrate and mixed feed samples, while deoxynivalenol and aflatoxin B1 were found at the frequency lower than 50%. Other metabolites, produced by Aspergillus, Fusarium, Penicillium, and Alternaria species, occurred in the samples. Flavoglaucin, 3-nitropropionic acid, averufin, and sterigmatocystin were the most prevalent Aspergillus metabolites. Common Fusarium metabolites occurring in the samples included moniliformin, beauvericin, and enniatins. For Penicillium metabolites, mycophenolic acid, questiomycin A, quinolactacin A, oxaline, citrinin, and dihydrocitrinone were frequently detected. The toxic Alternaria metabolites, alternariol, and alternariol monomethyl ether showed the high incidence in the samples. Plant metabolites were commonly found, mainly cyanogenic compounds and isoflavones, from cassava and soybean meal used as feed ingredients. Overall, 96.6% of feed samples contained at least two metabolites, in a range from 2 to 69. According to co-contamination of mycotoxins found in feed samples, zearalenone were mostly found in combination with fumonisin B1, deoxynivalenol, and aflatoxin B1. Fumonisin B1 co-occurred with aflatoxin B1 and deoxynivalenol. The mixtures of deoxynivalenol and aflatoxin B1, and of zearalenone, fumonisin B1 and deoxynivalenol were also found. Due to known individual toxicity of fungal and plant metabolites and possible additive or synergistic toxic effects of multi-mycotoxins, the occurrence of these metabolites and co-contaminants should be monitored continuously to ensure food safety through the dairy supply chain.