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Bacillus siamensis LDR was tested for its potential as a biocontrol agent against the phytopathogenic fungi Curvularia lunata BM and Ganoderma sp. TB4. Fermentation of B. siamensis LDR for the production of antifungal compound was performed in modified Czapex-Dox broth using hanjeli (Coix lacryma-jobi L.) starch as carbon source. The Bacillus siamensis LDR inoculum was 105 CFU/ mL, and fermentation was conducted for up to 16 days. Antibiosis assay conducted to test the antifungal activity of filtrate medium. The results showed inhibition of C. lunata BM and Ganoderma sp. TB4 were 47.08% and 85.99%, respectively on 14th day of fermentation. Antifungal assay of the crude extract from filtrate medium revealed growth inhibition of C. lunata BM (60.70%) and Ganoderma sp. TB4 (65.25%). Thin layer chromatography of the crude extract revealed pink-colored spots indicative of lipopeptide compounds. Analysis of the crude extract by ultraperformance liquid chromatography-mass spectrometry was tentatively identified as iturin A, bacillomycin F, and surfactin.

Plant pathogens are responsible for important damages to valuable crops causing important economic losses. Agrobiodiversity protection is crucial for the valorization of local varieties that could possess higher resistance to biotic and abiotic stress. At the beginning of germination, seeds are susceptible to pathogens attacks, thus they can release endogenous antimicrobial compounds of different natures in the spermosphere, to contrast proliferation of microorganisms. The work aimed at characterizing the maize of local variety Nostrano di Storo seed exudates secreted during the first phases of germination, to identify compounds active in the defense towards pathogens. Storo seed exudates were proven to inhibit

Here we report the discovery and identification of antibacterial substances from the secondary metabolites of a new strain Bacillus velezensis BA-26. The whole genome of B. velezensis BA-26 was sequenced. Its genome data were annotated, and four potentially unknown gene clusters and nine known secondary metabolite synthetic gene clusters were analyzed and excavated by antiSMASH software. Based on the predicted secondary metabolites from the genome of strain BA-26, the material identification of isolated and purified extracellular secondary metabolites was conducted in combination with mass spectrometry data. A total of 24 antifungal compounds were identified, namely, iturin and various fengycins. The minimum inhibitory concentration (MIC) of iturin to Botrytis cinerea was 62.50 µg·mL−1. The MICs of C14 fengycin A, C16 fengycin A and C18 fengycin A were 62.50, 31.25 and 0.49 µg·mL−1, respectively, indicating that the increase in the number of carbon atoms in side chain fatty acids of fengycin improves its biological activity. Two kinds of anti-disease fungal compounds from B. velezensis BA-26, namely, iturin and fengycin, were purified and identified; they were found to have antibacterial activities against common pathogenic fungi. Therefore, B. velezensis BA-26 may be potentially used as a biological control agent. This study enriches the genome information on B. velezensis, elucidates the active components of B. velezensis BA-26 antibacterial substances, and provides a useful reference for using strain BA-26 as a biological control agent. Supplemental data for this article is available online at https://doi.org/10.1080/13102818.2021.1934540 .

The gut microflora of insects plays important roles throughout their lives. Different foods and geographic locations change gut bacterial communities. The invasive wood-borer Agrilus mali causes extensive mortality of wild apple, Malus sieversii, which is considered a progenitor of all cultivated apples, in Tianshan forests. Recent analysis showed that the gut microbiota of larvae collected from Tianshan forests showed rich bacterial diversity but the absence of fungal species. In this study, we explored the antagonistic ability of the gut bacteria to address this absence of fungi in the larval gut. The results demonstrated that the gut bacteria were able to selectively inhibit wild apple tree-associated fungi. Among them, Pseudomonas synxantha showed strong antagonistic ability, producing antifungal compounds. Using different analytical methods, such as column chromatography, mass spectrometry, HPLC, and NMR, an antifungal compound, phenazine-1-carboxylic acid (PCA), was identified. Activity of the compound was determined by the minimum inhibitory concentration method and electron microscopy. Moreover, our study showed that the gut bacteria could originate from noninfested apple microflora during infestation. Overall, the results showed that in newly invaded locations, A. mali larvae changed their gut microbiota and adopted new gut bacteria that prevented fungal colonization in the gut.

Summary Many types of yeast have been studied in the last few years as potential biocontrol agents against different phytopathogenic fungi. Their ability to control plant diseases is mainly through combined modes of action. Among them, antibiosis, competition for nutrients and niches, induction of systemic resistance in plants and mycoparasitism have been the most studied. In previous work, we have established that the epiphytic yeast Pseudozyma aphidis inhibits Botrytis cinerea through induced resistance and antibiosis. Here, we demonstrate that P. aphidis adheres to B. cinerea hyphae and competes with them for nutrients. We further show that the secreted antifungal compounds activate the production of reactive oxygen species and programmed cell death in B. cinerea mycelium. Finally, P. aphidis and its secreted compounds negatively affect B. cinerea hyphae, leading to morphological alterations, including hyphal curliness, vacuolization and branching, which presumably affects the colonization ability and infectivity of B. cinerea. This study demonstrates additional modes of action for P. aphidis and its antifungal compounds against the plant pathogen B. cinerea.

Background: The gut microflora of insects plays important roles throughout their lives. Different foods and geographic locations change gut bacterial communities. The invasive wood-borer Agrilus mali causes extensive mortality of wild apple, Malus sieversii, which is considered a progenitor of all cultivated apples, in Tianshan forests. Recent analysis showed that the gut microbiota of larvae collected from Tianshan forests showed rich bacterial diversity but the absence of fungal species. In this study, we explored the antagonistic ability of gut bacteria to address this absence of fungi in the larval gut. Results: The results demonstrated that gut bacteria were able to selectively inhibit wild apple tree-associated fungi. However, Pseudomonas synxantha showed strong antagonistic ability, producing antifungal compounds. Using different analytical methods, such as column chromatography, mass spectrometry, HPLC and NMR, an antifungal compound, phenazine-1-carboxylic acid (PCA), was identified. Activity of the compound was determined by the minimum inhibitory concentration method and electron microscopy. Moreover, sequence alignment and cluster analysis showed that gut bacteria could originate from noninfested apple microflora during infestation. Conclusions: Overall, the results showed that in newly invaded locations, A. mali larvae changed their gut microbiota and adopted new gut bacteria that prevented fungal colonization in the gut.

Made available in DSpace on 2018-12-11T17:37:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-08-25 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Paracoccidioidomycosis (PCM) is a systemic mycosis endemic in Latin America, caused by Paracoccidioides spp. A limited number of antifungal agents are available and the search for new compounds has increased. Additionally, nanostructured lipid system (NLS) has emmerged as an interesting strategy to carrier compounds for the treatment of mycosis. In this work, the antifungal efficacy and toxicity of dodecyl gallate (DOD) associated with a NLS was evaluated through in vitro and in vivo tests. DOD showed good in vitro antifungal activity and low toxicity in lung fibroblasts and zebrafish embryos, but no antifungal efficacy in infected mice, which may have been a result of low bioavailability. On the other hand, the association of DOD + NLS was beneficial and resulted in lower toxicity in lung fibroblasts and zebrafish embryos. In addition, NLS + DOD promoted a significant reduction in the fungal burden of mice lungs and could be a potential therapeutic option against PCM. São Paulo State University (UNESP) School of Pharmaceutical Sciences São Paulo State University (UNESP) Institute of Biosciences Letters and Exact Sciences, São José do Rio Preto São Paulo State University (UNESP) School of Pharmaceutical Sciences São Paulo State University (UNESP) Institute of Biosciences Letters and Exact Sciences, São José do Rio Preto FAPESP: 2013/10917-9 FAPESP: 2014/10446-9 FAPESP: 2015/03700-9

Aims To evaluate the antifungal activity of the volatile organic compounds (VOCs) produced by 75 different food-borne Bacillus species against Aspergillus niger, Aspergillus flavus, Aspergillus parasiticus, Aspergillus clavatus, Fusarium oxysporum f. sp. lactucae and Moniliophthora perniciosa and to determine the VOCs responsible for the inhibition. Methods and Results Bacillus strains inhibited fungal growth, although with different inhibition grades, with Bacillus subtilis, Bacillus amyloliquefaciens and Bacillus cereus strains as the best antifungal VOCs producers. While M. perniciosa DM4B and F. oxysporum f.sp. lactucae MA28 were the most sensitive fungi, A. parasiticus MG51 showed the greatest resistance to Bacillus VOCs exposure. Thirty-seven compounds were detected by SPME-GC-MS analysis, although similar patterns in volatile compounds were evidenced within the species, interspecific VOCs differences determined different effects on fungal growth. Multiple partial least regression (MPLRS) and antifungal activity of the individual VOCs revealed that only propanone, 1-butanol, 3-methyl-1-butanol, acetic acid, 2-methylpropanoic acid, carbon disulphide, 3-methylbutanoic acid and ethyl acetate were responsible for mycelia inhibition of M. perniciosa DM4B and F. oxysporum f.sp. lactucae MA28. Conclusions The antagonistic activity of the Bacillus VOCs was demonstrated, although it cannot easily be explained through the action of a single molecule, thus a holistic approach could be more appropriate to estimate the fungal growth inhibition. Significance and Impact of the Study VOCs produced by Bacillus from cooked food can be considered as promising antifungal compounds useful in the control of fungal plant pathogens. This study investigates for the first time the correlation between mycelia inhibition of M. perniciosa and F. oxysporum f. sp. lactucae and the VOCs emitted by the Bacillus species.

Background Green and blue mold decay, caused by Penicillium digitatum and P. italicum, respectively, are important postharvest diseases of citrus. Biocontrol by microbes is an alternative to synthetic fungicide application. In this study, the antagonistic yeast strain Kloeckera apiculata 34–9 was used to investigate the action mechanisms involved in the biocontrol of postharvest diseases. Results An antifungal substance, 2-phenylethanol (PEA), was isolated from K. apiculata and demonstrated to have antimicrobial activity against selected phytopathogenic fungi. Experiments on P. italicum cells identified the mitochondria and the nucleus as particularly sensitive to inhibition. Regulation of P. italicum gene expression was investigated using RNA-Seq. PEA up-regulated genes involved with the peroxisome, regulation of autophagy, phosphatidylinositol signaling system, protein processing in endoplasmic reticulum, fatty acid metabolism, and inhibited ribosome, RNA polymerase, DNA replication, amino acid biosynthesis, aminoacyl-tRNA biosynthesis and cell cycle. Inhibitory responses revealed by RNA-Seq suggest that PEA might compete for attachment on the active site of phenylalanyl-tRNA synthetase (PheRS). Conclusion This study provided new insight on the mode of action of biocontrol yeast agents in controlling postharvest pathogenic fungi. Electronic supplementary material The online version of this article (doi:10.1186/s12866-014-0242-2) contains supplementary material, which is available to authorized users.

The morbidity, mortality and economic burden associated with fungal infections, together with the emergence of fungal strains resistant to current antimicrobial agents, necessitate broadening our understanding of fungal pathogenesis and discovering new agents to treat these infections. Using invertebrate hosts, especially the nematode Caenorhabditis elegans and the model insects Drosophila melanogaster and Galleria mellonella, could help achieve these goals. The evolutionary conservation of several aspects of the innate immune response between invertebrates and mammals makes the use of these simple hosts an effective and fast screening method for identifying fungal virulence factors and testing potential antifungal compounds. The purpose of this review is to compare several model hosts that have been used in experimental mycology to-date and to describe their different characteristics and contribution to the study of fungal virulence and the detection of compounds with antifungal properties. This article is part of a Special Issue entitled: Animal Models of Disease.

The aims of this study were to investigate the antifungal activity as a bioactive property of dihydrodehydrodiconiferyl alcohol 9′-O-β-d-glucoside (DDDC9G) and the mode of action(s) involved in its effect. Antifungal susceptibility testing showed that DDDC9G possessed potent antifungal activities toward various fungal strains with almost no hemolytic effect. To understand the antifungal mechanism(s) of DDDC9G, we conducted the following experiments in this study using Candida albicans. Fluorescence experiments using the probes, 1, 6-diphenyl-1, 3, 5-hexatriene (DPH) and propidium iodide suggested that DDDC9G perturbed the fungal plasma membrane. Consecutively, the analysis of the transmembrane electrical potential (ΔΨ) with 3, 3′-dipropylthiadicarbocyanine iodide [DiSC3(5)] and bis-(1, 3-dibutylbarbituric acid) trimethine oxonol [DiBAC4(3)] indicated that DDDC9G induced membrane-depolarization. Furthermore, model membrane studies were performed with rhodamine-labeled giant unilamellar vesicles (GUVs), calcein encapsulating large unilamellar vesicles (LUVs), and FITC-dextran (FD) loaded LUVs. These results demonstrated that the antifungal effects of DDDC9G upon the fungal plasma membrane were through the formation of pores with the radii between 0.74nm and 1.4nm. Finally, in three dimensional (3D) flow cytometric contour plots, a reduced cell size was observed as a result of osmolarity changes from DDDC9G-induced structural and functional membrane damages. Therefore, the present study suggests that DDDC9G exerts its antifungal effect by damaging the membrane through pore formation in the fungal plasma membrane.

In this study, we investigated the antifungal activity and mechanism of action of (+)-pinoresinol, a biphenolic compound isolated from the herb Sambucus williamsii, used in traditional medicine. (++)-Pinoresinol displays potent antifungal properties without hemolytic effects on human erythrocytes. To understand the antifungal mechanism of (+)-pinoresinol, we conducted fluorescence experiments on the human pathogen Candida albicans. Fluorescence analysis using 1,6-diphenyl-1,3,5-hexatriene (DPH) indicated that the (+)-pinoresinol caused damage to the fungal plasma membrane. This result was confirmed by using rhodamine-labeled giant unilamellar vesicle (GUV) experiments. Therefore, the present study indicates that (+)-pinoresinol possesses fungicidal activities and therapeutic potential as an antifungal agent for the treatment of fungal infectious diseases in humans.

Fusapyrone (1) and deoxyfusapyrone (2) are two 3-substituted-4-hydroxy-6-alkyl-2-pyrones isolated from Fusarium semitectum that have considerable antifungal activity against molds. Because of their low zootoxicity and selective action they are potentially utilizable along with biocontrol yeasts for control of postharvest crop diseases. Seven derivatives of 1 (3 and 5-10) and one derivative of 2 (4) were obtained by chemical modifications of the glycosyl residue, the 2-pyrone ring, the aliphatic chain, or a combination thereof, and a structure-activity correlation study was carried out with regard to their zootoxicity and antifungal activity. Derivatives 7-10, as well as 1, were slightly zootoxic in Artemia salina (brine shrimp) bioassays, whereas pentaacetylation of 1 into 3, 5, and 6 resulted in a strong increase in toxicity. Compound 4, the tetraacetyl derivative of 2, was as toxic as 2. Because the structural changes of 1 that resulted in an increase of biological activity in A. salina bioassay were those that affected mainly the water solubility of the molecule, it appears that toxicity is related to hydrophobicity. Compounds 1 and 2 showed strong antifungal activity toward Botrytis cinerea, Aspergillus parasiticus, and Penicilliun brevi-compactum (minimum inhibitory concentration at 24 h = 0.78-6.25 microg/mL). Among derivatives 3-10, only compounds 7, 9, and 10 retained some activity, limited to B. cinerea and at high concentration (25-50 microg/mL). None of the compounds 1-10 inhibited the growth of the biocontrol yeasts Pichia guilliermondii and Rhodotorula glutinis at the highest concentration tested (50 microg/mL).