Abstract Objective: Aflatoxin is known as one of the most important mycotoxins that threatens of human life. The toxin is produced by Aspergillus species which are common cause of contamination of agricultural products. For this reason, the use of organic compounds has always been considered in order to inhibit the growth of fungi and production of toxin. The aim of this study was to investigate the effect of vitamin C on the growth rate of fungi and the level of aflR gene expression (gene responsible for aflatoxin production). Material and method: At first, Aspergillus parasiticus ATCC15517 was cultured in SDA medium containing vitamin C with concentrations of 200, 100, 50, 25, 12.5, 6.25, 3.1 mg / ml at 28 ° C for 72 hours. Then, the amount of aflatoxin produced in the presence of vitamin C was measured by HPLC method. Finally, by extracting the DNA of cultured samples, the aflR gene expression level was evaluated by real-time PCR at different concentrations of vitamin C. Result: The results showed that the deformation of mycelium was started in medium with 50 mg / ml of vitamin C and only fungal spores were observed at higher concentrations. The results of measurement of toxin showed that the level of total aflatoxin and the subset of B 1, B 2, G 1 and G 2 were 5.9, 1.9, 0.2, 3.5 and 0.3 ppm in the presence of vitamin, respectively. While without the presence of vitamin C, these values were 207.5, 73.6, 4.5, 123.4, 6 ppm, respectively. Measuring the expression level of aflR genes, showed that at a concentration of 25 mg / ml of vitamin C, the level of gene expression is down 68%, and at the concentration of 50 mg / ml, the level of gene expression is decreased up to 81%. Conclusion: This study showed that vitamin C, as a human-compatible compound, could be considered as a good way to keep agricultural products from fungal aflatoxin.
Background and Purpose: Fusarium species are avid producers of secondary toxic and carcinogenic metabolites such as fumonisin. Contamination of food and feed products with fumonisin can be hazardous to the health of humans and animals and may lead to agricultural loss. Accordingly, in this study, we aimed to evaluate the effects of Candida parapsilosis on the growth and fumonisin production of Fusarium species. Materials and Methods:Mycelial growth rate of 26 Fusarium isolates, including F. verticillioides (n=6), F. proliferatum (n=18), F. solani (n=1), and F. oxysporum (n=1), in the presence of 42 C. parapsilosis strains was investigated by pour-plate method. The decline in fumonisin production was measured in co-cultured fungi in coarsely ground maize after four weeks of incubation in the dark at 22°C, using ELISA technique. For data analysis, paired t-test was performed, using SPSS version 20. Results:The mycelial growth and fumonisin production of Fusarium isolates significantly decreased in the presence of C. parapsilosis in comparison with the control cultures (P<0.05). The percentage of mycelial growth inhibition ranged from 56.36% to 74.54%. The minimum and maximum decline in total fumonisin production was 12% and 78%, respectively. F. oxysporum and F. solani were found to be minor fumonisin producers among the studied Fusarium species. On the other hand, a decline was reported in the growth of Fusarium species and fumonisin production in the presence of C. parapsilosis. Conclusion: C. parapsilosis showed notable inhibitory activities against Fusarium isolates. Therefore, this fungal species could be considered as a biocontrol agent against the growth and fumonisin production of toxigenic Fusarium species in the future.
Background and Purpose: The pandemic of COVID-19 has caused a worldwide health crisis. Candidemia is a potentially lethal condition that has not yet been enough discussed in patients with COVID‐ 19. The current study aimed to investigate the prevalence of candidemia among Iranian COVID‐ 19 patients and characterize its causative agents and the antifungal susceptibility pattern. Materials and Methods: The present cross-sectional survey was carried out from March 2020 to March 2021 at Imam Khomeini Hospital, Tehran, Iran. Blood specimens were obtained from patients with confirmed coronavirus infection who also had criteria for candidemia and were examined for any Candida species by conventional and molecular techniques. Susceptibility of isolates to amphotericin B, voriconazole, itraconazole, fluconazole, caspofungin, and 5-flucytosine was tested using the CLSI broth dilution technique. Results: In total, 153 patients with COVID-19 were included and candidemia was confirmed in 12 (7.8 %) of them. The majority of patients were ≥ 50 years of age (n=9) and female (n=8). Moreover, 6 out of the 12 patients were diabetic. The presence of central venous catheters, broad-spectrum antibiotic therapy, ICU admission, andmechanical ventilation was observed in all patients. The C. albicans (n=7, 58.3 %) and C. dubliniensis (n=2, 16.7%) were the most common isolated species. Amphotericin B and 5-flucytosine were the most active drugs. Despite antifungal treatment, 4 out of 12 patients (33.3 %) died. Conclusion: Due to the high mortality, the early diagnosis and proper treatment of candidemia are essential requirements for optimal clinical outcomes in COVID-19 patients.
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