Flavus Strains Research Articles

Genome sequence of Aspergillus flavus A7, a marine-derived fungus with antibacterial activity.

Due to the specific properties of the marine environment, marine microorganisms have exclusive physicochemical characteristics that are different from those of terrestrial microorganisms, which can produce various secondary metabolites (SMs) with considerable structural diversity and biological activity. In this study, three strains of coepiphytic Aspergillus with potential antibacterial activities, A7 (Aspergillus flavus), B27 (Aspergillus flavipes), and R12 (Aspergillus sydowii), were isolated from the South China Sea. Via the Illumina MiSeq sequencing platform, the genomes of the three strains were sequenced, and genome comparison showed the highest diversity of the biosynthetic gene clusters (BGCs) in A7. In addition, a comparison of physiological and genomic characteristics between A7 and other A. flavus strains demonstrated the superior environmental adaptability of A7, which is apparently consistent with the genetic richness of BGCs. By assigning reads to known BGCs, putative BGCs were allocated in A7 that corresponded to various SMs, including naphthopyrone, pyranonigrin E, and cyclopiazonic acids. Based on gene homology analysis, we surmise that a region is involved in the biosynthesis of ustiloxin-like RiPPs, a less thoroughly studied SM in fungi. Our results provide genetic information for the investigation of marine Aspergillus spp., which may help to elucidate their chemical diversity and adaptive strategies.

Comparison of biological methods to control Aphis fabae Scopoli (Hemiptera: Aphididae) on kalanchoe crops in East Africa

Aphids cause considerable damage to numerous crops all over the world and insecticides are the main means of controlling them, despite their detrimental impacts on human and environmental health. This study assessed the effectiveness of the parasitoid Aphidius colemani Viereck (Hymenoptera: Braconidae), a mixture of predatory ladybird beetles, Hippodamia variegata Goeze, Chilocorus calvus Chiccl, and Cheilomenes propinqua Mulsant (Coleoptera: Coccinellidae), and an entomopathogenic strain of Aspergillus flavus Link (Eurotiales: Trichocomaceae), collected locally in Tanzania, to control Aphis fabae Scopoli (Hemiptera: Aphididae). After assessing the predation and parasitism rates of these natural enemies at different aphid densities in laboratory experiments, their ability to control aphids on kalanchoe was assessed in a greenhouse experiment over two seasons. The largest number of A. fabae parasitized or consumed in the laboratory was found at a density of 160 aphids per predator, or parasitoid. At that density, an adult female of A. colemani parasitized 114 A. fabae per day, on average, and adults of C. calvus, H. variegata, and C. propinqua consumed 75, 72, and 85 aphids per day, respectively. A. flavus spores applied at 1 × 107 spores ml−1 reduced the aphid population by 7.9 and 12.6 times within 10 days in the first and second seasons of the greenhouse experiments, respectively, as opposed to 2.8 and 2.5 times by releasing a mixture of the ladybirds at a rate of 5 adults/m2, and by 3.3 and 9.5 times by releasing A. colemani at a rate of 2 adults/m2. This study confirmed the potential of these locally collected bio-control agents for controlling A. fabae. However, use of the isolated A. flavus strain was undermined by its production of aflatoxin. Further research is therefore required to tap into the potential of a non-toxic strain of A. flavus and/or other entomopathogenic fungi.

Microbial Aspect of some processed meat products with special reference to aflatoxins

This work was carried out to evaluate the microbial aspect of some processed meat products sold in local markets in Kaliobia governorate with special reference to aflatoxin. Eighty samples of random meat products, sausages and Kofta (40 of each) were purchased from different shops at Kaliobia Governorate. All examined for their microbiological criteria. All the examined samples found to be contaminated with different types of microorganisms with the mean values of 11×106 ± 5.4×106.,and 2.04×106 ± 0.12×106 respectively for total aerobic bacterial counts; 6.7×103± 0.3×103,and 1.2×103 ±0.16×103 respectively for total coliforms;1.1x 103 ± 0.14 x 103 and 1.4 x 103 ± 0.27 x 103, respectively for total mould count;and 0.52 x 103 ± .08 x 103 and 0.47 x 103 ± .07 x 103 total yeast count. The incidence of mould in the examined sausage was higher than kofta samples.The average conc. of aflatoxins in sausage was 19.8±2.5a with frequency and incidence of 13 (32.5%), while in kofta was 11.5 ±3.3a with frequency and incidence of 12 (30%). Aspergillus and Penicillium species were the most prevalent species recovered from the examined meat product samples. The isolated A. flavus strains were screened for aflatoxin production. The public health significance of isolated microorganisms as well as recommended hygienic measures to keep meat products safe were discussed as the result showed that the unhygienic and poor sanitary conditions of meat products.

Influence of a glyphosate-based herbicide on growth parameters and aflatoxin B1 production by Aspergillus section Flavi on maize grains

Glyphosate-based herbicides (GBH) are the main pesticides applied worldwide on maize production. Glyphosate-resistant weeds led to the repeated application of high doses of the pesticide. In addition to environmental conditions, the presence of GBH affects the development of Aspergillus species and aflatoxin B1 (AFB1) production under in vitro conditions. The aim of this work was to evaluate the influence of a commercial GBH on growth and AFB1 production by Aspergillus flavus and Aspergillus parasiticus strains under different water activity (aW) conditions. The following concentrations of active ingredient glyphosate were evaluated: 20, 50, 200 and 500mM. The lag phase prior to growth and growth rate did not change at 20 and 50mM (that is, at field recommended doses) at 0.98 and 0.95 aW; however, at increasing GBH concentrations, between 200 and 500mM, the growth rate decreased at all aW conditions. In general, as the GBH concentration increased, AFB1 production decreased. However, a significant increase in toxin accumulation was found only at one of the aW conditions (0.95) at 21 days with 50mM of GBH in A. flavus and 20 and 50mM of GBH in A. parasiticus. These results show that, even though Aspergillus section Flavi growth did not increase, AFB1 production increased on maize grains at GBH concentrations similar to those of field recommended doses under favorable water availability and temperature conditions.

Inhibitory Effects of Litsea cubeba Oil and Its Active Components on Aspergillus flavus

Aspergillus flavus (A. flavus) is a frequent harmful fungal pathogen. It can infect traditional Chinese medicine materials and release aflatoxin, to cause both economic and human health effects. By comparing the inhibitory potential of Litsea cubeba oil and its active components to A. flavus CGMCC 3.4408, citral was confirmed to be the main component that inhibits the growth of A. flavus CGMCC 3.4408, and the EC50 was 163.65 mg L−1. The inhibitory effect of citral on A. flavus CGMCC 3.4408 was studied for colony growth rate, mycelium biomass, aflatoxin production, and microstructure. Citral slowed down the growth rate of colonies and reduced mycelium biomass and toxin production. Moreover, citral altered the morphology of fungal spores and mycelium. In addition, citral also has the inhibitory effects on the isolates of A. flavus from moldy traditional Chinese medicinal materials. Thus, citral can be used as a potential agent to check the growth of A. flavus or related fungal strains.

Revisiting an Aspergillus flavus Strain Isolated from an Egyptian Sugarcane Field in 1930.

The aflatoxin type B and G producer Aspergillus novoparasiticus was described in 2012 and was firstly reported from sputum, hospital air (Brazil), and soil (Colombia). Later, several survey studies reported the occurrence of this species in different foods and other agricultural commodities from several countries worldwide. This short communication reports on an old fungal strain (CBS 108.30), isolated from Pseudococcus sacchari (grey sugarcane mealybug) from an Egyptian sugarcane field in (or before) 1930. This strain was initially identified as Aspergillus flavus; however, using the latest taxonomy schemes, the strain is, in fact, A. novoparasiticus. These data and previous reports indicate that A. novoparasiticus is strongly associated with sugarcane, and pre-harvest biocontrol approaches with non-toxigenic A. novoparasiticus strains are likely to be more successful than those using non-toxigenic A. flavus strains. Further studies on the association between A. novoparasiticus and Pseudococcus sacchari might shed light on the distribution (and aflatoxin contamination) of this species in sugarcane. Additionally, the interaction between A. novoparasiticus, Pseudococcus sacchari, and sugarcane crop under different scenarios of climate change will be critical in order to get more insight into the host–pathogen interaction and host resistance and propose appropriate prevention strategies to decrease mycotoxin contamination and crop loss due to A. novoparasiticus attack.

Efficacy of Cinnamomum cassia essential oil against food-borne molds and aflatoxin B1 contamination

The present study deals with the antifungal and antiaflatoxigenic potential of Cinnamomum cassia essential oil (CCEO) against aflatoxigenic food borne Aspergillus flavus strain (AF-LHP-PE-4), and probable mode of action including the safety profile on male mice. CCEO completely inhibited fungal growth and aflatoxin B1 secretion at its minimum inhibitory concentration (0.06 µL/mL). CCEO inhibited ergosterol biosynthesis in cell membranes and also disturbed the membrane fluidity. Significant enhancement in leakage of cellular ions and 260 and 280 nm absorbing cellular materials in response to increased concentrations of CCEO indicated the plasma membrane as the probable site of antifungal toxicity. The antiaflatoxigenic potency of CCEO was confirmed in terms of reduction in the level of cellular methylglyoxal (MG), the inducer of aflatoxin. Antioxidant activity of CCEO was confirmed through DPPH free radical scavenging activity as well as total phenolic content. Chemical profiling of CCEO by gas chromatography-mass spectrometry (GC-MS) analysis revealed the presence of cinnamaldehyde (84.01%) as the most abundant compound. CCEO exhibited a high LD50 (10410.75 µL/kg) on male mice, strengthening its favorable safety profile. This is the first report on CCEO as novel green preservative against food storage molds and aflatoxin B1 secretion.

Mycotoxicological and physicochemical study of infant flour marketed in south-west of Algeria and anti-mycotoxin effect of the aqueous extract of Anethum graveolens L.

The current work focuses on a mycotoxicological study and the control of the physicochemical quality of infantile flours marketed in the city of Bechar in the South-West of Algeria, thus aiming to study phenolic composition, antioxidant activity and efficacy of the anti-mycotoxin effect of the aqueous extract of Anethum graveolents L. The mycotoxicological analysis revealed that the first sample of the infant flour type I (FIT I/E1) is unsatisfactory product with a contamination rate 12.54 × 103UF/g whose 40% of Aspergillus flavus strains isolated are producers of aflatoxin B1and 50% of A ochraceus are producers of ochratox in A. The aqueous extract of A graveolens L. showed significant anti-mycotoxin activity, A flavuswas inhibited from a minimum inhibitory concentration MIC of 300 μg/ml and A ochraceusat 650 μg/ml. The total phenol content is also determined for extract. The antioxidant activitie was estimated and the aqueous extract showed a good scavenging activity with a concentration providing 50% inhibition (IC50)value of 0,14±0,31 mg/ml.

Modelling the effect of temperature and water activity on the growth rate of Aspergillus flavus and aflatoxin production in peanut meal extract agar

Aspergillus flavus is the predominant species that produce aflatoxins in stored peanuts under favourable conditions. This study aimed to describe the growth and aflatoxin production by two A. flavus strains isolated from imported raw peanuts and to model the effects of temperature and aw on their colony growth rate as a function of temperature and aw in Peanut Meal Extract Agar (PMEA). A full factorial design with seven aw levels (0.85–0.98 aw) and five temperature levels (20–40 °C) was used to investigate the growth and aflatoxin production. Colony diameter was measured daily for 28 days while AFB1 and total aflatoxin were determined on day 3, 7, 14, and 21. The maximum colony growth rate, μmax (mm/day) was estimated by using the primary model of Baranyi, and the μmax was then fitted to the secondary model; second-order polynomial and linear Arrhenius-Davey to describe the colony growth rate as a function of temperature and aw. The results indicated that both strains failed to grow at temperature of 20 °C with aw <0.94 and aw of 0.85 for all temperatures except 30 °C. The highest growth rate was observed at 30 °C, with 0.98 aw for both strains. The analysis of variance showed a significant effect of strain, temperature, and aw on the fungal growth and aflatoxin production (p < 0.05). Furthermore, both secondary models were in good agreement with the observed μmax. However, the polynomial model was found to be a better predictor of the experimental data. A similar pattern was observed in aflatoxin production but in a narrower range of temperature (25–35 °C) and aw (0.92–0.98 aw). The highest production of aflatoxins was observed on day 21 at 30 °C with the aw level of 0.98 for both strains. Overall, the current findings may help in improving the mycotoxin management and intervention strategies in peanuts, especially during storage.

Secretome produced by a newly isolated Aspergillus flavus strain in engineered medium shows synergy for biomass saccharification with a commercial cellulase

In this study, we evaluated the saccharification potential of the secretome produced by a new elephant faeces isolate Aspergillus flavus (AF-NGF1), alone as well as in combination with a commercial enzyme (CTec2). Medium engineering (involving sequential Taguchi design, response surface methodology and one factor at a time approaches) enhanced the cellulase (FPase) secretion in the secretome of isolate AF-NGF1 (AF-S) by 3.89-folds. AF-S showed a maximum increase of 7.1- and 8.69-folds in exo-glucanase (avicellase) and endo-glucanase (CMCase) activities, respectively. Equal enzyme loading (20 FPU/g of biomass) of AF-S and CTec2 showed comparable saccharification potential with acid pre-treated paddy straw (APPS). However, a 1:1 combination of AF-S and CTec2 showed 67.84% and 37.21% increased saccharification of APPS as compared with AF-S or CTec2 alone at 50 °C and 40 °C, respectively. During simultaneous saccharification and fermentation (SSF) at 40 °C, a 1:1 combination produced > 2-folds increased ethanol titre as compared with AF-S or CTec2 alone. When equal FPU of AF-S and CTec2 were mixed for a total of 20 FPU, the degree of synergy (DOS) for APPS saccharification was 1.79 ± 0.06 and ~ 30.49% increased FPase activity was detected, which suggested the synergistic correlation between AF-S and CTec2. Therefore, the combination of AF-S and CTec2 could be considered as a potential cellulolytic enzyme formulation for efficient biomass hydrolysis and SSF process for lignocellulosic ethanol production.

Genetic polymorphisms associated to SDHI fungicides resistance in selected Aspergillus flavus strains and relation with aflatoxin production

Aspergillus flavus is a common and ubiquitous fungal species able to colonize several agricultural commodities, in both pre- and post-harvest conditions. This species represents a very harmful plant pathogen for its ability to synthesize aflatoxin B1, responsible for human primary hepatocellular carcinoma and classified as a group I (human carcinogenic) by the International Agency for Research on Cancer. Several approaches have been proposed to control A. flavus development and related aflatoxin production in field and storage conditions. The Succinate Dehydrogenase Inhibitor (SDHI) fungicide boscalid has been shown to control A. flavus growth and aflatoxin contamination both in vitro and in field experiments. However, this compound is classified as medium-high risk fungicide for triggering fungal resistance and, indeed, resistant strains can occur on crops treated with boscalid.In this paper, we selected laboratory A. flavus strains resistant to boscalid grown on agar medium containing 50 mg/L of boscalid. In order to investigate the molecular mechanism responsible for the resistant phenotype, specific primer pairs were designed to amplify the whole SdhB, SdhC and SdhD genes. By amino acid sequence analysis, two point mutations, Tyrosine replacing Histidine at codon 249 of SdhB (H249Y) and Arginine replacing Glycine at codon 91 of SdhC (G91R), were identified. The effect of SDHI boscalid and isopyrazam on mycelial growth and conidial germination was evaluated. Both resistant genotypes showed high resistance (MIC and EC50 > 1000 mg/L) to boscalid. A positive cross-resistance was found between boscalid and isopyrazam.Specific sub-lethal doses of both fungicides (0.5 mg/L of boscalid and 0.01 mg/L of isopyrazam) interfered with the mechanisms associated to pigmentation of colonies. In particular, fungal colonies appeared depigmented lacking the typical A. flavus green colour shown on un-amended fungicide medium. A strict correlation between lack of pigmentation and increasing aflatoxin production was also observed.

Complete mitochondrial genome sequence of Afla-Guard®, commercially available non-toxigenic Aspergillus flavus

Afla-Guard® is a commercial non-toxigenic Aspergillus flavus strain used to decrease aflatoxin contamination level in field. Its mitochondrial genome was sequenced, showing that its length is 29,208 bp with typical configuration of Aspergillus mitochondrial genome. 17 SNPs and 27 INDELs were identified by comparing with previous A. flavus mitochondrial genome. Phylogenetic trees present that A. flavus of Afla-Guard® was clustered with the previous A. flavus mitochondrial genome.

Degradation and Transformation of Lignin by a Fungus Aspergillus Flavus Strain F-1.

Background: Lignin is the largest natural aromatic polymer in nature and is also a unique aromatic-based biopolymer, accounting for nearly 30% of the earth’s organic carbon. Generally, lignin is regarded as waste and is mainly used as a low- value fuel that is burned to generate heat and energy to solve the problem of biomass waste; for this obstacle of lignin, highly efficient biodegradation plays a critical role in developing an environmentally friendly technique for lignin biotransformation.Objectives: This study intends to isolate and purify several microbial strains from nature. It also explores how their lignin degradation is able to enhance the biodegradation and recycling of biomass and the reclamation of lignin in wastewater from pulp and paper mills.Materials and Methods: Lignin-degrading microbial strains were isolated from soil using medium containing sodium lignosulphonate as the sole carbon source. They were then screened by aniline blue and guaiacol plate, and then the best strain was chosen and identified. The conventional one-factor method was used to optimize various parameters that affect lignin’s degradation ability.Results: The strain possessing the highest lignin biodegradation ability was identified and denominated as Aspergillus Flavus F-1. After optimization, the maximum degradation rate of lignin, 44.6% within 3 days, was obtained at pH 7.0, 30 ℃, 2.5 g·L-1 ammonium sulfate, 2 g·L-1 lignin and 0.5 g·L-1 glucose. The results show the LiP and Lac secreted from Aspergillus Flavus F-1 played the main role in the degradation of lignin.Conclusion: One microbial strain, Aspergillus Flavus F-1, was successfully isolated with a lignin-degrading ability that can cut the lignin into fragments. This provides a promising candidate for the transformation and utilization of crop waste biomass for various industrial purposes.

Decolorization of Synthetic Dyes by Aspergillus flavus Strain EF-3 Isolated from Textile Dyeing Sludge

Treatment of textile and dyeing wastewater using indigenous dye-degrading microorganisms is considered to be a sustainable bioremediation strategy. In the present study, a dye-decolorizing fungal strain was isolated from dyeing sludge and identified as Aspergillus flavus strain EF-3 on the basis of cultural, morphological and internal transcribed spacer (ITS) region sequencing. The fungal strain was tested to decolorize five commercially available textile reactive dyes and dye mixture as well. The decolorization efficiencies were ranged from 62% to 100% for 100 mg/L concentration of each dye in Czapek Dox broth within 6 days of incubation at 27°C, and 120 rpm batch-culture conditions. The dyes Novacron Brilliant Blue FN-R, Bezema Yellow S8-G and dye mixture were completely decolorized within the stipulated time period. The nature of decolorization was found to be co-metabolic, i.e., dyes were not used as the sole source of energy for fungal growth and required an external co-substrate, sucrose for induction of decolorization process. The dye removal mechanism involves initial biosorption of the dye in fungal mycelium followed by subsequent biodegradation to colorless end-product. The findings of the present study provide valuable insights to desgin effective biological treatment for dyeing wastewater using the fungus Aspergillus flavus.&#x0D; Bangladesh J Microbiol, Volume 37 Number 1 June 2020, pp 7-13

The Inhibitory Effect of Validamycin A on Aspergillus flavus.

Aspergillus flavus is one of the most common isolates from patients with fungal infections. Aspergillus infection is usually treated with antifungal agents, but side effects of these agents are common. Trehalase is an essential enzyme involved in fungal metabolism, and the trehalase inhibitor, validamycin A, has been used to prevent fungal infections in agricultural products. In this study, we observed that validamycin A significantly increased trehalose levels in A. flavus conidia and delayed germination, including decreased fungal adherence. In addition, validamycin A and amphotericin B showed a combinatorial effect on A. flavus ATCC204304 and clinical isolates with high minimum inhibitory concentrations (MICs) of amphotericin B using checkerboard assays. We observed that validamycin A and amphotericin B had a synergistic effect on A. flavus strains resistant to amphotericin B. The MICs in the combination of validamycin A and amphotericin B were at 0.125 μg/mL and 2 μg/mL, respectively. The FICI of validamycin A and amphotericin B of these clinical isolates was about 0.25–0.28 with synergistic effects. No drug cytotoxicity was observed in human bronchial epithelial cells treated with validamycin A using LDH-cytotoxicity assays. In conclusion, this study demonstrated that validamycin A inhibited the growth of A. flavus and delayed conidial germination. Furthermore, the combined effect of validamycin A with amphotericin B increased A. flavus killing, without significant cytotoxicity to human bronchial epithelial cells. We propose that validamycin A could potentially be used in vivo as an alternative treatment for A. flavus infections.

Biological and molecular modeling studies on some transition metal(II) complexes of a quinoxaline based ONO donor bishydrazone ligand

In this report, synthesis, characterization, biological and molecular modeling studies of an ONO donor tridentate bishydrazone ligand, 3-[N′-(2-Hydroxy-3-methoxy-benzylidene)-hydrazino]-1H-quinoxalin-2-one (HHQ) and its 1:1 mononuclear Co(II) (HHQ-1), Ni(II) (HHQ-2), Cu(II) (HHQ-3) and Zn(II) (HHQ-4) complexes have been conferred. Octahedral geometry was assigned to HHQ-1, HHQ-2 and HHQ-4 and distorted octahedral geometry for HHQ-3. The lattice parameters, morphology and electrochemical behaviors of the compounds were studied by powder XRD, SEM and cyclic voltammetry analyses respectively. The antimicrobial assays were carried out against the bacterial (Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa) and fungal (Aspergillus flavus, Aspergillus niger and Candida albicans) strains. Furthermore, the DNA binding, cleaving and superoxide dismutase (SOD) activities of HHQ and its metal(II) complexes were discussed. The structures of HHQ and its derivatives were optimized by DFT techniques. Using molecular docking the molecular interaction dynamics amongst the DNA and SOD with HHQ and its metal(II) complexes were recognized. Communicated by Ramaswamy H. Sarma

Antimicrobial Activities of Rhopalaea-Associated Fungus Aspergillus flavus strain MFABU9.

Rhopalaea is a genus of ascidian belonging to the family Diazonidae. Ascidians provide niches for various microorganisms including fungi. This present study describes the potential new source for natural bioactive compounds from Rhopalaea-associated fungi obtained from Bunaken marine park. As part of an on-going research program to explore the chemical diversity of marine derived fungi, we performed an antimicrobial bioactivity-guided screening of EtOAc extracts of the fungi isolated from ascidian Rhopalaea sp. The study confirms that the ascidian obtained from Bunaken marine park was Rhopalaea sp. The fungus isolated from the ascidian was Aspergillus flavus which showed antimicrobial activity against bacteria Escherichia coli, Staphylococcus aereus, Aeromonas hydrophila and antifungal against the human pathogenic fungus Candida albicans. Aspergillus flavus isolated from ascidian Rhopalaea sp. has the potential as antibacterial and antifungal.

Soil Microbial Communities in Corn Fields Treated with Atoxigenic Aspergillus flavus

Aspergillus flavus refers to a diverse group of saprophytic soil fungi that includes strains producing aflatoxins (toxigenic strains) in the kernels of corn (Zea mays L.) and other crops, causing pre-harvest and post-harvest aflatoxin contamination. Some A. flavus strains are atoxigenic, and the introduction of such strains into the crop environment helps reduce toxigenic aflatoxin contamination. Corn growers in Texas have used the product FourSure™, which contains four atoxigenic strains of A. flavus; however, effects on soil microbial communities associated with these applications are unknown. We compared soil fungal and bacterial communities in corn fields treated with FourSure™ to nearby untreated (control) corn fields in Texas during the summer of 2019. Analysis of soil microbial community structure showed that total fatty acid methyl esters (FAMEs), fungal, and bacterial populations were not significantly different (p = 0.31) between the FourSure™-treated and control fields, yet corn fields located in the northern counties had more (p &lt; 0.05) Gram—bacteria, actinobacteria, and total bacteria than fields in the southernmost county. The Gram—bacteria and actinobacteria were positively correlated (p = 0.04; r = 0.48 and 0.49, respectively) with soil water content. Similar fungal and bacterial abundances between FourSure™-treated and control fields indicated that atoxigenic A. flavus had no negative effects on soil microbial communities.

A non-toxigenic Aspergillus flavus strain prevents the spreading of Fusarium verticillioides and fumonisins in maize

We evaluated Fusarium verticillioides and fumonisin contamination in maize samples after application of a non-aflatoxigenic Aspergillus flavus strain in the field. The sampling was performed 150 days after planting. The results showed a reduction in F. verticillioides frequency, as well as in fumonisin levels when samples were obtained from field areas treated with non-aflatoxigenic A. flavus strain. These results suggested a competition for substrate or space between fungi reducing the frequency of F. verticillioides and, consequently, fumonisin production.

The high efficacy of luliconazole against environmental and otomycosis Aspergillus flavus strains

Luliconazole is currently confirmed for the topical therapy of dermatophytosis. Moreover, it is found that luliconazole has in vitro activity against some molds and yeast species. The aim of the present study was to evaluate the efficacy of luliconazole in comparison to routine used antifungals on clinical and environmental isolates of Aspergillus flavus. Thirty eight isolates of A. flavus (18 environmental and 20 clinical isolates) were detected based on morphological and microscopic features and also PCR-sequencing of β-tubulin ribosomal DNA gene. All the isolates were tested against luliconazole, voriconazole, amphotericin B and caspofungin. Minimum inhibitory concentration (MIC), MIC50, MIC90 and MIC Geometric (GM) were calculated using CLSI M38-A2 protocol for both environmental and clinical isolates. Luliconazole with extremely low MIC range, 0.00049-0.00781 μg/mL and MICGM 0.00288 μg/mL showed very strong activity against both clinical and environmental A. flavus isolates. Moreover, voriconazole inhibited 100% of isolates at defined epidemiological cutoff values (ECV ≤ 2 μg/ml). 50% and 27.8% of clinical and environmental isolates of A. flavus, were resistant to caspofungin, respectively. Whereas, all the isolates were found to be resistant to amphotericin B. The analysis of our data clearly indicated that luliconazole (with MICGM 0.00244 μg/ml for clinical and 0.00336 μg/ml for environmental isolates) had the highest in vitro activity against A. flavus strains.