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In a previous study, raw cashew kernels were assayed for the fungal contamination focusing on strains belonging to the genus Aspergillus and on aflatoxins producers. These samples showed high contamination with Aspergillus section Nigri species and absence of aflatoxins. To investigate the diversity of secondary metabolites, including mycotoxins, the species of A. section Nigri may produce and thus threaten to contaminate the raw cashew kernels, 150 strains were isolated from cashew samples and assayed for their production of secondary metabolites using liquid chromatography high resolution mass spectrometry (LC-HRMS). Seven species of black Aspergilli were isolated based on morphological and chemical identification: A. tubingensis (44%), A. niger (32%), A. brasiliensis (10%), A. carbonarius (8.7%), A. luchuensis (2.7%), A. aculeatus (2%) and A. aculeatinus (0.7%). From these, 45 metabolites and their isomers were identified. Aurasperone and pyranonigrin A, produced by all species excluding A. aculeatus and A. aculeatinus, were most prevalent and were encountered in 146 (97.3%) and 145 (95.7%) isolates, respectively. Three mycotoxins groups were detected: fumonisins (B2 and B4) (2.7%) ochratoxin A (13.3%), and secalonic acids (2%), indicating that these mycotoxins could occur in raw cashew nuts. Thirty strains of black Aspergilli were randomly sampled for verification of species identity based on sequences of β-tubulin and calmodulin genes. Among them, 27 isolates were positive to the primers used and 11 were identified as A. niger, 7 as A. tubingensis, 6 as A. carbonarius, 2 as A. luchuensis and 1 as A. welwitschiae confirming the species names as based on morphology and chemical features. These strains clustered in 5 clades in A. section Nigri. Chemical profile clustering also showed also 5 groups confirming the species specific metabolites production.

HighlightsThe first study on characterization of the extracts obtained from industrial pecan nut processing byproducts.Chemical composition and biological activity of the extracts varied with type of byproduct and the pecan cultivars used in the process.Pecan shell extracts exhibited anticancer, antioxidant, and antimicrobial activity.Abstract. Industrial processing of pecan nuts produces large amounts of shells, which have economic significance for pecan growers and processors. Hence, it is imperative that valorization of pecan processing byproducts is explored. In this study, byproducts from commercial pecan shelling operations were evaluated as potential sources of biologically active phytochemicals. Shelling byproducts from Pawnee, Native, and Stuart cultivars were examined. Aqueous ethanol shell extracts were analyzed for their chemical composition using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF/MS). Total phenolic content, DPPH radical scavenging capacity, anticancer activity, and antimicrobial activity of the samples were investigated. The chemical composition and biological activity of the shell extracts varied significantly with the pecan cultivar and type of byproduct stream used in the study. The presence of nut meat pieces in the byproducts resulted in high oil content in the extracts. The extract from Pawnee cultivar showed high DDPH activity, low IC50 for cancer cell lines, and high IC50 for the healthy cell line (Vero). Extracts from all cultivars had antimicrobial activity against Escherichia coli at relatively high disk loadings. This is the first study on the biological activity of extracts obtained from commercial pecan shelling byproducts. The findings of this study have significant practical implications and provide the initial data much needed for valorization of industrial pecan shelling byproducts. Keywords: Anticancer activity, Antimicrobial activity, Chemical composition, Pecan shell extract.

BACKGROUND: Olive oil production is an important economical activity in the Aegean region of Turkey. However, the effluents of the olive oil producing mills with their high organic loads and toxic compounds are causing serious environmental problems. The anaerobic biological treatment of olive mill wastewater (OMWW) using the treatment plants of the regional industries could be a method of choice and within the scope of this study floccular and granular sludges were investigated in batch mode for their success in the treatment of OMWW while producing biogas.The major limitation of this treatment is the inhibition of methanogenic bacteria by the phenolic compounds in OMWW. Thus an integrated solution was suggested in which a pre-treatment step (dephenolization) was also introduced before biological step.

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