Abstract
Aflatoxins are produced as secondary metabolites by A. flavus, A. parasiticus, A. nomius and A. tamarii. The aflatoxin biosynthetic pathway involves several enzymatic steps and genes (apa-2, ver-1) that appear to be regulated by the aflR gene in these fungi. The aim of this work was the detection of aflatoxins by the HPLC method and the ascertainment of factors influencing their production. A. parasiticus CCM F-108, A. parasiticus CCF 141, A. parasiticus CCF 3137 and two isolates A. flavus were used. These toxigenic isolates were recovered from spice (strain 1) and wraps (strain 2). The gene for the production of aflatoxin B1 for each species of fungi was detected using an optimized PCR method. Rhodotorula spp.*, Lactococcus lactis subsp. lactis CCM 1881, Flavobacterium spp. and fungal strain Pythium oligandrum* were tested for inhibition of aflatoxins production and fungal growth. Having used the HPLC detection, various preservatives (propionic acid, citric acid, potassium sorbate) were tested from the viewpoint of their influence on the growth of aflatoxigenic fungi followed by the production of aflatoxins. The growth of A. flavus and A. parasiticus and aflatoxin production in Potato Dextrose Agar supplemented with propionic acid (1000-2000-3000 mg/kg), citric acid (2000-3000-4000 mg/kg) and potassium sorbate (500-800-1000 mg/kg) was tested by Agar Dilution Method. After 72 h of incubation was evaluated growth of fungi, all samples were frozen for later extraction and aflatoxins quantification by HPLC. Effect of peptone and sucrose additions were studied in yeast extract (2%) supplemented with peptone (5-10-15%) or sucrose (15%). Growth inhibition of Aspergillus by Pythium oligandrum was tested on wood surface. As shown, the highest inhibition effect on the aflatoxins production was obtained when propionic acid was applied in concentrations since 1000 mg/kg. A total inhibition of the fungi growth and aflatoxins production was observed in all samples containing peptone in the concentration range tested. Significant limitation of the growth and production of aflatoxins was also observed in the presence of other microorganisms such like Pythium oligandrum and Rhodotorula spp.
Highlights
Microscopic filamentous fungi present a worldwide problem
Production of aflatoxins in potato dextrose broth The optimized polymerase chain reaction (PCR) reaction selectivity was tested on collection cultures and it was proven that both PCR methods are highly specific for the determination of aflatoxinogenic strains of A. flavus and A. parasiticus isolated from food and feed
Production of aflatoxin B1 corresponds to the data in the literature on the production of aflatoxin B1 found in Aspergillus parasiticus FVB 1981 isolated from peanut sauce, which were incubated in YES broth at 28 °C for 7 days, 10.8 ng/mL (Abarca et al, 1988)
Summary
Microscopic filamentous fungi present a worldwide problem. Fungal physiology refers to the nutrition, metabolism, growth and reproduction of fungal cells. It generally relates to interaction of fungi with their biotic and abiotic environment, including cellular response to stress. Fungi are responsible for the organic pollutants detoxification and for the bioremediation of heavy metals in the environment. The fungal negative effect on humans, animals and plants is the main reason for monitoring the contamination of food and feed (Gunterus et al 2007, Huang et al 2009). Some fungi colonize plant seeds and thereby cause loss of stored harvests and reduce seed germination rates, they can produce mycotoxins which have mutagenic properties. Some fungi are pathogens of plants or animals (and even other fungi). Fungi can cause diseases in humans, many of them as so-called opportunistic pathogens that attack people whose immune systems are weakened
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
