Screening of Bacillus velezensis E2 and the Inhibitory Effect of Its Antifungal Substances on Aspergillus flavus

Aspergilus flavus is the main pathogenic fungus that causes food mold. Effective control of A. flavus contamination is essential to ensure food safety. The lipopeptides (LPs) produced by Bacillus strains have been shown to have an obvious antifungal effect on molds. In this study, an antagonist strain of Bacillus velezensis with obvious antifungal activity against A. flavus was isolated from the surface of healthy rice. Using HPLC-MS analysis, the main components of LPs produced by strain E2 were identified as fengycin and iturins. Further investigations showed that LPs could inhibit the spore germination, and even cause abnormal expansion of hyphae and cell rupture. Transcriptomic analyses showed that some genes, involved in ribosome biogenesis in eukaryotes (NOG1, KRE33) and aflatoxin biosynthesis (aflK, aflR, veA, omtA) pathways in A. flavus were significantly down-regulated by LPs. In conclusion, this study provides novel insights into the cellular and molecular antifungal mechanisms of LPs against grain A. flavus contamination.

UHPLC-HRMS-Based Untargeted Lipidomics Reveal Mechanism of Antifungal Activity of Carvacrol against Aspergillus flavus

Aspergillus flavus is a common contaminant in grain, oil and their products. Its metabolite aflatoxin B1 (AFB1) has been proved to be highly carcinogenic. Therefore, it is of great importance to find possible antifungal substances to inhibit the growth and toxin production of Aspergillus flavus. Carvacrol (CV) was reported as a potent antifungal monoterpene derived from plants. In this paper, the antifungal effects and mechanism of CV on Aspergillus flavus were investigated. CV was shown good inhibition on the growth of Aspergillus flavus and the production of AFB1. CV used in concentrations ranging from 0, 50, 100 and 200 μg/mL inhibited the germination of spores, mycelia growth and AFB1 production dose-dependently. To explore the antifungal mechanism of CV on Aspergillus flavus, we also detected the ergosterol content of Aspergillus flavus mycelia, employed Scanning Electron Microscopy (SEM) to observe mycelia morphology and utilized Ultra-High-Performance Liquid Chromatography-High-Resolution Mass Spectrometry (UHPLC-HRMS) to explore the lipidome profiles of Aspergillus flavus. The results showed that the production of ergosterol of mycelia was reduced as the CV treatment concentration increased. SEM photographs demonstrated a rough surface and a reduction in the thickness of hyphae in Aspergillus flavus treated with CV (200 µg/mL). In positive ion mode, 21 lipids of Aspergillus flavus mycelium were downregulated, and 11 lipids were upregulated after treatment with 200-µg/mL CV. In negative ion mode, nine lipids of Aspergillus flavus mycelium were downregulated, and seven lipids upregulated after treatment with 200-µg/mL CV. In addition, the analysis of different lipid metabolic pathways between the control and 200-µg/mL CV-treated groups demonstrated that glycerophospholipid metabolism was the most enriched pathway related to CV treatment.

The effect of lichen secondary metabolites on Aspergillus fungi

A systematic review of literature data on the antifungal potential of extracted lichen compounds and individual secondary metabolites against mold species of the genus Aspergillus is provided. Crude extracts from 49 epiphytic, 16 epigeic and 22 epilithic species of lichens and 44 secondary metabolites against 10 species, Aspergillus candidus, A. flavus, A. fumigatus, A. nidulans, A. niger, A. ochraceus, A. parasiticus, A. restrictus, A. stellatus and A. ustus, were analysed. Several measuring techniques were employed for such analyses. Lichen substances were extracted with alcoholic and other organic solvents mainly using the Soxhlet apparatus. Among the three most-studied mold species, the results showed that the crude extracts from the thalli of the lichens Cladonia foliacea, Hypotrachyna cirrhata, Leucodermia leucomelos, Platismatia glauca and Pseudevernia furfuracea against Aspergillus flavus, from C. foliacea, Nephroma arcticum and Parmelia sulcata against A. fumigatus and from Evernia prunastri, Hypogymnia physodes, Umbilicaria cylindrica and Variospora dolomiticola against A. niger have the greatest antifungal potential. The lichen secondary metabolites showed a higher inhibitory potential, e.g. protolichesterinic acid against A. flavus, lecanoric acid against A. fumigatus and orsellinic acid against A. niger; the other seven species of Aspergillus have been poorly studied and require further investigation. A comparison of the inhibitory potential of the tested mixtures of lichen substances and their secondary metabolites shows that they can compete with commonly used antifungal substances, such as ketoconazole and clotrimazole against A. flavus, A. nidulans, A. niger and A. parasiticus and fluconazole in the case of A. fumigatus.

The antagonistic mechanism of Bacillus velezensis ZW10 against rice blast disease: Evaluation of ZW10 as a potential biopesticide

Rice blast, caused by the fungus Magnaporthe oryzae, is one of the three major diseases affecting rice production and quality; it reduces rice grain yield by nearly 30%. In the early stage of this study, a strain of Bacillus velezensis with strong inhibition of M. oryzae was isolated and named ZW10. In vitro assays indicated prolonged germination time of conidia of M. oryzae treated with the antifungal substances of ZW10, 78% of the conidia could not form appressorium, and the conidial tubes expanded to form vacuolar structure and then shrank. The results of FDA-PI composite dyes showed that the antifungal substances of ZW10 inhibited the normal activity of M. oryzae hyphae that were rarely able to infect the epidermal cells of rice leaf sheath in vivo tests. In addition, rice treated with the antifungal substances of ZW10 showed a variety of defense responses, including activation of defense-related enzymes, increased expression of the salicylic acid pathway genes, and accumulation of hydrogen peroxide (H2O2), which might function directly or indirectly in resistance to pathogen attack. The field experiment with rice blast infection in different periods showed that the antifungal substances of ZW10 had the same control effect as carbendazim. The significant biological control activity of ZW10 and its capacity to stimulate host defenses suggest that this B. velezensis strain has the potential to be developed into a biopesticide for the biocontrol of rice blast.

Mycotoxins Biocontrol Methods for Healthier Crops and Stored Products

Contamination of crops with phytopathogenic genera such as Fusarium, Aspergillus, Alternaria, and Penicillium usually results in mycotoxins in the stored crops or the final products (bread, beer, etc.). To reduce the damage and suppress the fungal growth, it is common to add antifungal substances during growth in the field or storage. Many of these antifungal substances are also harmful to human health and the reduction of their concentration would be of immense importance to food safety. Many eminent researchers are seeking a way to reduce the use of synthetic antifungal compounds and to implement more eco-friendly and healthier bioweapons against fungal proliferation and mycotoxin synthesis. This paper aims to address the recent advances in the effectiveness of biological antifungal compounds application against the aforementioned fungal genera and their species to enhance the protection of ecological and environmental systems involved in crop growing (water, soil, air) and to reduce fungicide contamination of food derived from these commodities.

Formulation of an Ointment from Hydroethanolic Extract of Terminalia ivorensis and Therapeutic Trial on Volunteers with Moths

This study was conducted to make a contribution in the treatment of dermatosis, particularly moths. Ointments of different concentrations made from the hydroethanolic extract of Terminalia ivorensis and shea butter were used. The best results were obtained with the following concentrations: C4: 0.01 g/mL; C5: 0.0125 g/mL; C6: 0.015 g/mL and C10: 0.025 g/mL for trichophytic clipping moth on eleven (11) selected persons with ringworm and C9: 0.0225 g/mL for microsporic clipping moth on one (1) person. The present study really provides the scientific basis for the use of this plant in the traditional treatment of diseases and may help to discover new chemical classes of antifungal substances that could serve as selective agents for infectious disease chemotherapy.

Screening of Antifungal Substances from Bovistella Radicata (Mont.) Pat and Their Antifungal Effect

Background To analyse the antifungal active compounds in B. radicata alcohol extract, the alcohol extract was purified by column chromatography (macroporous resinD-101) and the active compounds was named as SPAF-1(the spore powder active fraction). Results Alcohol extracts and SPAF-1 were submitted to GC-MS analysis, there were two characteristic peaks(peak1 and peak2) in Gas chromatogram. By comparing in NIST, the compound were 2-propyl-1-pentanol corresponding to peak1 and decanal, n-decanol and 2E-decanol corresponding to peak2. The main constituents were decanal(24.3%) n-decanol(27.9%), 2E-decenol (21.2%) and 2-Propyl-1-pentanol (13.6%). Their MIC values were 62.5 µg/ml, 31.2 µg/ml, 31.2 µg/ml and 250 µg/ml against T. rubrum respectively. Furthermore, transmission electron microscope (TEM) analysis showed altered surface morphology in the majority of T. rubrum cells after treatment with SPAF-1. Conclusions In this paper, we successfully separate SPAF-1 from alcohol extract of B. radicata. The antifungal effect of SPAF-1 is similar to positive control, the main component were decanal, n-decanol, 2E-decenol and 2-Propyl-1-pentanol, the anti-tinea pedis effect of them was obvious.

Heavy metals in livers of raptors from Eastern Poland – the importance of diet composition

Concentrations of Pb, Cd, Ni, Cr and Hg were determined in livers of six species of raptors collected in the area of Eastern Poland. Redundancy analysis (RDA) showed that elevated Hg and Cr concentrations were directly related to feeding on passerines. Raptors that specialised in seizing small mammals as a source of food revealed higher hepatic concentrations of Pb and Cd in comparison with other raptors. Unlike Cd, we found statistically significant differences in the Pb concentrations in livers of Common buzzards as compared to Sparrowhawks. In spite of the fact that both Goshawks and Sparrowhawks hunt birds, only the latter species had accumulated significantly more mercury. The high concentrations of Hg in Sparrowhawks could be related to the use of mercury in antifungal substances for seed dressing.