Abstract
The present study was aimed to establish the antagonistic effects of Ocimum sanctum L. essential oil (OSEO) on growth and zearalenone (ZEA) production of Fusarium graminearum. GC–MS chemical profiling of OSEO revealed the existence of 43 compounds and the major compound was found to be eugenol (34.7%). DPPH free radical scavenging activity (IC50) of OSEO was determined to be 8.5 μg/mL. Minimum inhibitory concentration and minimum fungicidal concentration of OSEO on F. graminearum were recorded as 1250 and 1800 μg/mL, respectively. Scanning electron microscope observations showed significant micro morphological damage in OSEO exposed mycelia and spores compared to untreated control culture. Quantitative UHPLC studies revealed that OSEO negatively effected the production of ZEA; the concentration of toxin production was observed to be insignificant at 1500 μg/mL concentration of OSEO. On other hand ZEA concentration was quantified as 3.23 μg/mL in OSEO untreated control culture. Reverse transcriptase qPCR analysis of ZEA metabolic pathway genes (PKS4 and PKS13) revealed that increase in OSEO concentration (250–1500 μg/mL) significantly downregulated the expression of PKS4 and PKS13. These results were in agreement with the artificially contaminated maize grains as well. In conlusion, the antifungal and antimycotoxic effects of OSEO on F. graminearum in the present study reiterated that, the essential oil of O. sanctum could be a promising herbal fungicide in food processing industries as well as grain storage centers.
Highlights
The existence of fungal species and their toxic secondary metabolites viz. mycotoxins in food and feed commodities is a major concern for microbiological safety and food security (Pitt and Hocking, 2009)
Chemical Composition Based on the dry weight calculation, the yield of Ocimum sanctum L. essential oil (OSEO) was determined as 1.79% (w/w)
Chemical profile of OSEO was revealed by GC-mass spectra (MS) analysis and a total of 43 compounds were identified accounting to 98.03% of the total weight (Table 2)
Summary
The existence of fungal species and their toxic secondary metabolites viz. mycotoxins in food and feed commodities is a major concern for microbiological safety and food security (Pitt and Hocking, 2009). Mycotoxins in food and feed commodities is a major concern for microbiological safety and food security (Pitt and Hocking, 2009). Fungi and their mycotoxins could cause massive financial loss to global economy, because of their deleterious effects in cereal crops besides humans and farm animals (Rocha et al, 2014). Among the toxigenic and pathogenic fungal species, Fusarium graminearum has been given special attention in agriculture commodities due to its ability to grow in diverse climatic conditions, and to produce different mycotoxins including ZEA and type-B trichothecenes (Morgavi et al, 2007; Bernhoft et al, 2012). In another study, Pleadin et al (2012) reported a maximum concentration of 5.11 mg/kg ZEA in maize
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