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The present study examines the influence of the natural preservatives carvacrol, eugenol, trans-cinnamaldehyde and the essential oil (EO) Origanum vulgare on ochratoxin A (OTA) production and the mycelial growth of two food-related moulds, Penicillium verrucosum and Aspergillus westerdijkiae, by broth macro-dilution assay for 21 days. With the addition of ½ minimum inhibitory concentration (MIC) carvacrol, eugenol and O. vulgare EO, the mycelial dry weight of both moulds decreased significantly over the whole incubation period of 7, 14 and 21 days. Trans-cinnamaldehyde slightly stimulated the growth of A. westerdijkiae and P. verrucosum at 14 and 21 days of incubation. Growth inhibition did not accompany inhibition of OTA production. Although the growth of both moulds was inhibited after the addition of ½ MIC carvacrol, eugenol and O. vulgare EO, the OTA production of the strong mycotoxin producer A. westerdijkiae was stimulated. Only trans-cinnamaldehyde inhibited the production of OTA with the addition of ½ MIC. P. verrucosum produced significantly less OTA than A. westerdijkiae, and its mycotoxin production was almost completely inhibited by the addition of ½ MIC of the natural preservatives. [ABSTRACT FROM AUTHOR]

This study deals with the efficacy of Origanum onites, Salvia officinalis, and Mentha piperita essential oils (EOs) and their mixture (1:1:1, v/v/v) against ochratoxigenic P. verrucosum D-99756 and modelling the effects of EOs on fungal growth using modified Gomperz and logistic models. O. onites, S. officinalis, and M. piperita EOs were used at their minimal lethal concentration levels at 65, 125, and 250 μL/mL, respectively, which were determined in our preliminary studies. Inactivation of fungi sporulation by EO treatments was higher than 50-60% within 48 h, while 78.50-81.41% lethality was observed at the end of the 168 h for all of the tested EOs. The most effectiveness time for lethal effect was found at 84 h for O. onites and S. officinalis, while it was 168 h for mix EOs (p < 0.05). The modified Gompertz model successfully produced better fits than the logistic model as evidenced by the root mean square error, the modelling efficiency, and accuracy efficiency. In conclusion, data confirmed the potential use of plant and spice EOs for their fungistatic and fungicidal effects in food systems. [ABSTRACT FROM AUTHOR]

Cereals are among the most vulnerable substrates to mycotoxin contamination. One of the major fungal species colonising the ecosystem of stored grain isPenicillium verrucosumbecause of its ability to produce ochratoxin A (OTA). Knowledge of favourable environmental conditions promoting fungal growth and mycotoxin biosynthesis seems to be a crucial step towards preventing mycotoxin formation in stored grain. The aim of the study was to examine the effect of temperature and different cereal substrates (wheat, triticale, rye, barley, maize, rice) on fungal growth and OTA and citrinin (CIT) production by a mycotoxin-producingP. verrucosumstrain at one moisture content. The correlation between fungal growth and mycotoxin biosynthesis was also investigated. For this purpose, cereal substrates moistened, autoclaved and inoculated withP. verrucosumspores were stored at 10°C, 20°C and 30°C for 40 days. After the storage period, the ergosterol (ERG) content as a fungal growth biomarker and OTA and CIT levels were determined using HPLC. Fungal growth was observed on all cereals at each temperature. Maximum ERG levels were found at 30°C and the values ranged from 401 to 3280 mg kg−1of grain. Among tested cereals, the highest ergosterol content was found on rice at all applied temperatures. Accumulation of OTA and CIT was detected in samples stored at 20°C and 30°C, while optimal conditions for the production of both mycotoxins were observed at 20°C. The maximum concentration of OTA (31.9 ± 4.3 (SD) μg kg−1) and CIT (74.8 ± 5.7 μg kg−1) were found on rice. The ability to biosynthesise OTA and CIT at 10°C was not detected. Analysis of variance showed that single factors, temperature and cereal matrices and their interactions had significant effects on ERG, OTA and CIT levels. Optimal conditions for fungus growth did not coincide with the ones for mycotoxin formation. [ABSTRACT FROM AUTHOR]

Gallic acid (3,4,5-trihydroxybenzoic acid) was produced by microbial biotransformation of coffee pulp tannins byPenicillium verrucosum. Gallic acid production was optimized using response surface methodology (RSM) based on central composite rotatable design. Process parameters such as pH, moisture, and fermentation period were considered for optimization. Among the various fungi isolated from coffee by-products,Penicillium verrucosumproduced 35.23 µg/g of gallic acid on coffee pulp as sole carbon source in solid-state fermentation. The optimum values of the parameters obtained from the RSM were pH 3.32, moisture 58.40%, and fermentation period of 96 hr. Gallic acid production with an increase of 4.6-fold was achieved upon optimization of the process parameters. The results optimized could be translated to 1-kg tray fermentation. High-performance liquid chromatography (HPLC) analysis and spectral studies such as mass spectroscopy (MS) and1H-nuclear magnetic resonance (NMR) confirmed that the bioactive compound isolated was gallic acid. Thus, coffee pulp, which is available in enormous quantity, could be used for the production of value-added products that can find avenues in food, pharmaceutical, and chemical industries. [ABSTRACT FROM AUTHOR]

Mycotoxins are natural, secondary metabolites produced by fungi on agricultural commodities in the field and during storage under a wide range of climatic conditions. The ochratoxin A (OTA) is a nephrotoxic mycotoxin produced by several species of Aspergillus and Penicillium. In this study, the influence of carbon and nitrogen sources on ochratoxigenic Penicillium species was assessed. The ochratoxigenic Penicillium species were isolated from poultry feed samples of Andhra Pradesh, India. The isolated ochratoxigenic Penicillium species were identified, screened and characterised as OTA producers by high performance thin layer chromatography (HPTLC) and confirmed by high performance liquid chromatography (HPLC). This experiment was carried out using Czapak yeast Autolysate (CYA) medium with different carbon (C) and nitrogen (N) sources at pH 6.5 and incubated at 25 ± 2°C under dark condition. Maximum OTA production was recorded in the presence of D-glucose followed by D-galactose and D-lactose as carbon sources. Similarly, the maximum amount of OTA production was observed in thiourea followed by potassium nitrate as nitrogen source. However, OTA production, final pH of the medium, and mycelial yield and OTA production of both the species of Penicillium varied with C and N present in the medium. The kinetics of the both species of Penicillium was observed for 30 days at an interval of three days. The maximum amount of OTA was detected by 12 and 15 days incubation periods for Penicillium nordicum and Penicillium verrucosum, respectively. [ABSTRACT FROM AUTHOR]

Citrinin production characteristics of Penicillium citrinum and Penicillium verrucosum in black table olives stored at five different temperatures were investigated. Citrinin in both the media and olives were detected by thin layer chromatography (TLC). P. verrucosum produced citrinin at 20°C and 25°C on malt extract agar (MEA), czapek yeast extract agar (CYA), and yeast extract agar (YES), but not in olives. P. citrinum produced citrinin at 20°C, 25°C, and 30°C on both the media and in black olives. Citrinin was also detected in black olive samples stored in water at 30°C for 60 days of storage. NaCl in brine affected citrinin production in a positive way. [ABSTRACT FROM AUTHOR]

Ochratoxin A (OTA) is a secondary metabolite produced by several species of Aspergillus and Penicillium ; among them Aspergillus ochraceus and Penicillium verrucosum are two ochratoxigenic species capable of growing in different climates and thus contamination of food crops with OTA can occur worldwide. OTA can be found in a wide range of foods such as cereals, coffee, cocoa, spices, beer, wine, dried vine fruit, grapes and meat products. OTA is toxic to animals, it presents neurotoxic, immunotoxic and nephrotoxic effects. It has been implicated in a human kidney disorder known as Balkan Endemic Nephropathy. This review focuses on the ecophysiology of ochratoxin-producing Aspergillus ochraceus and Penicillium verrucosum , the effect of environmental factors on their germination, mycelial growth, and OTA production. Knowledge of environmental conditions required for sucessive stages of fungal development represent the first step towards preventing mycotoxin formation. Predictive models for different stages of fungal development are presented, which allow prediction of the time before spoilage as a function of the abiotic factors. Finally, the implications of these studies in management of barley, coffee and grapes are described. This can help to identify the critical control points in their production, storage and distribution processes. [ABSTRACT FROM AUTHOR]