The main objective of this study is to evaluate the effect of selected essential oils thyme chemotype linalool (Thymus zygis L.), thyme chemotype tymol (Thymus vulgaris L.), eucalyptus (Eucalyptus globulus Labill.), lavender (Lavandula angustifolia Mill.), mint (Mentha piperita L.), almond (Prunbus dulcis Mill.), cinnamon bark (Cinnamomum zeylanicum Nees), litsea (Litsea cubeba Lour. Pers), lemongrass (Cympogon citrati L. Stapf), and ginger (Zingiber officinalis Rosc.) in the vapor phase on growth, sporulation, and mycotoxins production of two Aspergillus strains (Aspergillus parasiticus CGC34 and Aspergillus ochraceus CGC87), important postharvest pathogens of green and roasted coffee beans. Moreover, the effect of the essential oils (EOs) on the sensory profile of the coffee samples treated with EOs was evaluated. The major components of tested EOs were determined by gas chromatography and mass spectrometry (GC–MS) and gas chromatography with flame ionization detector (GC-FID). The results showed that almond, cinnamon bark, lemongrass, and litsea EOs are able to significantly inhibit the growth, sporulation, and mycotoxins production by toxigenic fungi. Sensory evaluation of coffee beans treated with EOs before and after roasting showed that some EOs (except lemongrass and litsea) do not adversely affect the taste and aroma of coffee beverages. Thus, application of the vapors of almond and cinnamon EOs appears to be an effective way that could serve to protect coffee during its transport and storage from toxigenic fungi.
This study aimed to investigate the antagonistic effect of three strains of the genus Bacillus on toxigenic fungi contaminating food commodities, with emphasis on two ochratoxigenic isolates (A. ochraceus, A. westerdijkiae) and two aflatoxigenic isolates (A. flavus and A. parasiticus). In vitro studies were carried out using two different methods for cultivation tested bacilli with fungal isolatescoincubation and dual culture method. The most sensitive isolate was A. ochraceus by both used methods. B. mycoides (5.72 ± 6.4 mm) and B. subtilis (5.08 ± 2.84 mm) were able to inhibit its growth and sporulation during ten days of cultivation (both inhibited the sporulation of A. ochraceus 100%) in coincubation. The most effective in the dual culture method were B. subtilis and B. thuringiensis against A. ochraceus (growth inhibition rate 84.40%; 90.55%) and A. flavus (growth inhibition rate 91.54%; 92.43%). The most effective sporulation inhibitors were B. subtilis and B. thuringiensis, which completely inhibited the sporulation of A. ochraceus and A. parasiticus after ten days of coincubation. Likewise, all tested bacterial strains showed complete inhibition of ochratoxin A synthesis in A. ochraceus and A. westerdijkiae exposure to bacterial volatiles. So, the current study illustrated that strains of the genus Bacillus could significantly inhibit the growth, sporulation, and mycotoxin production of toxigenic aspergilli and showing the great potential as a biocontrol agent of preand post-harvest food diseases caused by microscopic filamentous fungi. ARTICLE INFO
A total of 20 samples of green and roasted coffee beans (the same varieties as green coffee beans were used) [Coffea arabica L. (19 samples) and Coffea robusta L. (1 sample)] were collected from the various coffee roasters in Slovakia (2017/2020) and their mycobiota were analyzed. Mycological analysis was carried using standard media with focus on genera Aspergillus and Penicillium. To determine endogenous and exogenous mycobiota the method of direct placing of surface-sterilized coffee beans (green and roasted) on agar plates and the plate dilution method were used. All obtained pure cultures were classified into the genera and identified to the species according to micro- and macromorphological properties. Next the potentially toxigenic isolates were tested on their ability to produce mycotoxins (cyclopiazonic acid, penitrem A, sterigmatocystin, aflatoxins (AFB1, AFG1), ochratoxin A, patulin, roquefortine C, citrinin, and griseofulvin). From green coffee samples with higher isolation frequency (FR%) and relative density (RD%) were the genus Aspergillus (FR 100% and RD 67.39%) and the genus Penicillium (FR 90% and RD 24.60%) recorded. Aspergillus section Nigri was the most widespread in green coffee samples (RD 47.7%). The genus Aspergillus was the most occurred genus in roasted coffee bean samples, too (RD 36.58%; FR 90%). In green and roasted coffee samples were detected mainly producers of aflatoxins (AFB1 and AFG1), cyclopiazonic acid, OA, sterigmatocystin and patulin. Due to the detected presence of mycotoxins in green as well as in roasted coffee bean samples, it is very important to prevent fungal contamination and control of coffee beans before and after roasting process.
This study was aimed to monitor the inhibitory effect of selected species of the genus Lactobacillus on growth and ochratoxin A production of the microscopic filamentous fungus Aspergillus ochraceus (SLO-B-245). Nine species of the genus Lactobacillus were used in this study, namely L. bifermentatus. L. perolens, L. reuteri, L. paracasei, L. paraplantarum, L. plantarum, L. salivarius, L. fructivorans and L. pentosus. All strains were isolated from dairy products and their identification was performed by MALDI TOF MS (Bruker Daltonics, Germany, Maldi Biotyper). The antifungal activity was carried out using the overlay technique. Solid culture media inoculated with bacterial and fungal inocula were cultivated under aerobic conditions at 37 ºC for 8 days. Diameters (Ø mm) of the grown fungal colonies were measured every two days. To determine the inhibition of ochratoxin A production, the thin-layer chromatography method (TLC) was used. L. plantarum and L. paraplantarum were able to inhibit the growth of A. ochraceus (SLO-B-245) completely (100% inhibition), while L. fructivorans appeared to be the least effective (10.73%). Interestingly, the latter one was able to completely inhibit or partially suppress ochratoxin A production. We hope that our results can contribute to the search for harmless substances for the biological control of fungi in food. Lactobacilli and similar organisms could be very promising alternatives for food preservation.
Nowadays, it is very important to find out the protection of plant products as an alternative to synthetic fungicides. The promising alternative is the use of the essential oils (EOs). The aim of our research was to evaluate the antifungal effect of angelica (Angelica archangelica L.), anise (Pimpinella anisum L.), fennel (Foeniculum vulgare Miller.), camphore (Cinnamonum camphorum Nees & Eberm), litsea (Litsea deccanensis L.), cumin (Carum carvi L.), dill (Anethum graveolens L.), thyme (Thymus vulgaris L.), mint (citrate) (Mentha citrata L.), mint (piperita) (Mentha piperita L.), laurel (Laurus nobilis L.), cinnamon (Cinnamomum zeylanicum L.) EOs against three isolates of the genus Rhizopus obtained from moldy plants source the chemical composition of selected EOs was determined by gas chromatography coupled with mass spectrometry (GC – MS) and by gas chromatography with flame ionization detector (GC – FID). The antifungal activity of EOs against the growth of Rhizopus spp. was investigated by gas diffusion method (625 μL/L of air). The mycelium growth inhibition was measured on the 2nd, 4th, and 7th days of cultivation. Six EOs: litsea, mint (citrata), mint (piperita), cumin, thyme and cinnamon completely inhibited the growth of all tested fungi. For these EOs the minimum inhibitory doses were determined. According to probit analyses, the most effective tested EO was thyme and the least effective was cumin. Our results indicated that EOs are effective in the vapor phase and had a potential antifungal activity against Rhizopus stolonifer strains. So, they could be utilized in novel biological fungicide development.
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