Antifungal activity of fatty acids and their monoglycerides againstFusariumspp. in a laboratory medium

Genotype-by-genotype interkingdom cross-talk between symbiotic nitrogen fixing Sinorhizobium meliloti strains and Trichoderma species

In the understanding of the molecular interaction between plants and their microbiome, a key point is to identify simplified models of the microbiome including relevant bacterial and fungal partners which could also be effective in plant growth promotion. Here, as proof-of-concept, we aim to identify the possible molecular interactions between symbiotic nitrogen-fixing rhizobia and soil fungi (Trichoderma spp.), hence shed light on synergistic roles rhizospheric fungi could have in the biology of symbiotic nitrogen fixation bacteria. We selected 4 strains of the model rhizobium Sinorhizobium meliloti and 4 Trichoderma species (T. velutinum, T. tomentosum, T. gamsii and T. harzianum). In an experimental scheme of 4 ×4 strains x species combinations, we investigated the rhizobia physiological and transcriptomic responses elicited by fungal spent media, as well as spent media effects on rhizobia-host legume plant (alfalfa, Medicago sativa L.) symbiosis. Fungal spent media had large effects on rhizobia, specific for each fungal species and rhizobial strains combination, indicating a generalized rhizobia genotype x fungal genotype interaction, including synergistic, neutral and antagonistic effects on alfalfa symbiotic phenotypes. Differential expression of a high number of genes was shown in rhizobia strains with up to 25% of total genes differentially expressed upon treatment of cultures with fungal spent media. Percentages over total genes and type of genes differentially expressed changed according to both fungal species and rhizobial strain. To support the hypothesis of a relevant rhizobia genotype x fungal genotype interaction, a nested Likelihood Ratio Test indicated that the model considering the fungus-rhizobium interaction explained 23.4% of differentially expressed genes. Our results provide insights into molecular interactions involving nitrogen-fixing rhizobia and rhizospheric fungi, highlighting the panoply of genes and genotypic interactions (fungus, rhizobium, host plant) which may concur to plant symbiosis.

Impact of lactic acid bacteria inoculation on fungal diversity during Spanish-style green table olive fermentations

This study delved into the evolution of fungal population during the fermentation of Spanish-style green table olives (Manzanilla cultivar), determining the influence of different factors such as fermentation matrix (brine or fruit) or the use of a lactic acid bacteria inoculum, on its distribution. The samples (n = 24) were directly obtained from industrial fermentation vessels with approximately 10.000 kg of fruits and 6.000 L of brines. Our findings showcased a synchronized uptick in lactic acid bacteria counts alongside fungi proliferation. Metataxonomic analysis of the Internal Transcribed Spacer (ITS) region unearthed noteworthy disparities across different fermentation time points (0, 24, and 83 days). Statistical analysis pinpointed two Amplicon Sequence Variants (ASV), Candida and Aureobasidium, as accountable for the observed variances among the different fermentation time samples. Notably, Candida exhibited a marked increase during 83 days of fermentation, opposite to Aureobasidium, which demonstrated a decline. Fungal biodiversity was slightly higher in brines than in fruits, whilst no effect of inoculation was noticed. At the onset of fermentation, prominently detected genera were also Mycosphaerella (19.82 %) and Apohysomyces (16.31 %), hitherto unreported in the context of table olive processing. However, their prevalence dwindled to nearly negligible levels from 24th day fermentation onwards (<2 %). On the contrary, they were replaced by the fermentative yeasts Saccharomyces and Isstachenkia. Results obtained in this work will be useful for designing new strategies for better control of table olive fermentations.

Cactus Endophytic Fungi and Bioprospecting for their Enzymes and Bioactive Molecules: A Systematic Review

Endophytic fungi are associated with plant health and represent a remarkable source of potential of enzymes and bioactive compounds, but the diversity of endophytes remains uncertain and poorly explored, especially in Cactaceae, one of the most species-rich families adapted to growing in arid and semi-arid regions. The aim of this study was to conduct a systematic review on the diversity and bioprospecting of endophytic fungi from Cactaceae. We analysed peer-reviewed articles from seven databases using PRISMA guidelines. The results showed that the Cactaceae family is a source of new taxa, but the diversity of endophytic fungi of Cactaceae is little explored, mainly the diversity among tissues and by metagenomics. Bioprospecting studies have shown that these microorganisms can be used in the production of enzymes and larvicidal and antifungal compounds. Our results are relevant as a starting point for researchers to develop studies that expand the knowledge of plant mycobiota in arid and semi-arid ecosystems, as well as comprising a remarkable source of fungal compounds with several biotechnological applications.

Armeria maritima (Mill.) Willd. Flower Hydromethanolic Extract for Cucurbitaceae Fungal Diseases Control

The cliff rose (Armeria maritima), like other halophytes, has a phenolics-based antioxidant system that allows it to grow in saline habitats. Provided that antioxidant properties are usually accompanied by antimicrobial activity, in this study we investigated the phytochemicals present in a hydromethanolic extract of A. maritima flowers and explored its antifungal potential. The main phytocompounds, identified by gas chromatography-mass spectrometry, were: hexadecanoic acid, octadecanoic acid, 9-octadecenoic acid, 3-(3,4-dihydroxy-phenyl)-acrylic acid ethyl ester, and benzeneacetaldehyde. The antifungal activity of the extract and its main constituents-alone and in combination with chitosan oligomers-was tested against six pathogenic taxa associated with soil-borne diseases of plant hosts in the family Cucurbitaceae: Fusarium equiseti, F. oxysporum f. sp. niveum, Macrophomina phaseolina, Neocosmospora falciformis, N. keratoplastica, and Sclerotinia sclerotiorum. In in vitro tests, EC₉₀ effective concentrations in the 166-865 μg·mL^-1 range were obtained for the chitosan oligomers-A. maritima extract conjugate complexes, lower than those obtained for fosetyl-Al and azoxystrobin synthetic fungicides tested for comparison purposes, and even outperforming mancozeb against F. equiseti. In ex situ tests against S. sclerotiorum conducted on artificially inoculated cucumber slices, full protection was achieved at a dose of 250 μg·mL^-1. Thus, the reported results support the valorization of A. maritima as a source of biorationals for Cucurbitaceae pathogens protection, suitable for both organic and conventional agriculture.

Effect of Refining and Fractionation Processes on Minor Components, Fatty Acids, Antioxidant and Antimicrobial Activities of Shea Butter

Shea butter is becoming increasingly popular in foods, cosmetics and pharmaceutical products. This work aims to study the effect of the refining process on the quality and stability of fractionated and mixed shea butters. Crude shea butter, refined shea stearin, olein and their mixture (1:1 w/w) were analyzed for fatty acids, triacylglycerol composition, peroxide value (PV), free fatty acids (FFA), phenolic (TPC), flavonoid (TFC), unsaponifiable matter (USM), tocopherol and phytosterol content. Additionally, the oxidative stability, radical scavenging activity (RSA), antibacterial and antifungal activities were evaluated. The two main fatty acids in the shea butter samples were stearic and oleic. The refined shea stearin showed lower PV, FFA, USM, TPC, TFC, RSA, tocopherol and sterol content than crude shea butter. A higher EC50 was observed, but antibacterial activity was much lower. The refined olein fraction was characterized by lower PV, FFA and TFC in comparison with crude shea butter, but USM, TPC, RSA, EC50, tocopherol and sterol content was unchanged. The antibacterial activity was higher, but the antifungal activity was lower than those of crude shea butter. When both fractions were mixed, their fatty acid and triacylglycerol composition were similar to those of crude shea butter, but other parameters were different.

Trichoderma asperellum empowers tomato plants and suppresses Fusarium oxysporum through priming responses

Plant-associated microbes play crucial roles in plant health and promote growth under stress. Tomato (Solanum lycopersicum) is one of the strategic crops grown throughout Egypt and is a widely grown vegetable worldwide. However, plant disease severely affects tomato production. The post-harvest disease (Fusarium wilt disease) affects food security globally, especially in the tomato fields. Thus, an alternative effective and economical biological treatment to the disease was recently established using Trichoderma asperellum. However, the role of rhizosphere microbiota in the resistance of tomato plants against soil-borne Fusarium wilt disease (FWD) remains unclear. In the current study, a dual culture assay of T. asperellum against various phytopathogens (e.g., Fusarium oxysporum, F. solani, Alternaria alternata, Rhizoctonia solani, and F. graminerarum) was performed in vitro. Interestingly, T. asperellum exhibited the highest mycelial inhibition rate (53.24%) against F. oxysporum. In addition, 30% free cell filtrate of T. asperellum inhibited F. oxysporum by 59.39%. Various underlying mechanisms were studied to explore the antifungal activity against F. oxysporum, such as chitinase activity, analysis of bioactive compounds by gas chromatography–mass spectrometry (GC–MS), and assessment of fungal secondary metabolites against F. oxysporum mycotoxins in tomato fruits. Additionally, the plant growth-promoting traits of T. asperellum were studied (e.g., IAA production, Phosphate solubilization), and the impact on tomato seeds germination. Scanning electron microscopy, plant root sections, and confocal microscopy were used to show the mobility of the fungal endophyte activity to promote tomato root growth compared with untreated tomato root. T. asperellum enhanced the growth of tomato seeds and controlled the wilt disease caused by the phytopathogen F. oxysporum by enhancing the number of leaves as well as shoot and root length (cm) and fresh and dry weights (g). Furthermore, Trichoderma extract protects tomato fruits from post-harvest infection by F. oxysporum. Taking together, T. asperellum represents a safe and effective controlling agent against Fusarium infection of tomato plants.

Anu Taila, an herbal nasal-drop, delays spore germination in Cunninghamella bertholletiae by reducing cAMP-PKA dependent ROS in mucorale pathogen and extrinsic ROS in human host cells

The rare, fastest-germinating, frequently invasive mucorale, Cunninghamella bertholletiae, is intractable due to its imprecise etiology. Cunninghamella bertholletiae spores can infect both immunocompromised and immunocompetent individuals to cause mucormycosis. Sub-optimal drug-susceptibility further limits its treatment options. The classical nasal drop, Anu Taila, is reported to be effective against the rather prevalent mucorales, Mucor spp., making its anti-mucormycotic effect against C. bertholletiae worth testing. The inhibitory effect of Anu Taila against C. bertholletiae was manifested as microstructural alterations of the spores and their delayed germination. Anu Taila reduced the germination-promoting reactive oxygen species (ROS) levels in both the pathogen, C. bertholletiae, and the human host lung epithelial A549 cells. Expressions of structural (chitin synthase, trehalose synthase) and functional (cAMP-PKA) markers of spore germination were regulated by Anu Taila. cAMP-PKA expression and ROS generation are well-correlated, implicating the role of Anu Taila in delaying C. bertholletiae spore germination by targeting cAMP-PKA-mediated ROS generation. In conclusion, this study demonstrates that Anu Taila can create an opportunity for the host immune system to tackle the onset of C. bertholletiae infection by delaying its pathogenesis. This can be further leveraged to reinforce the host immune system through combinatorial treatment to prevent the establishment of the mucormycosis infection.

Lipophilic Compounds and Antibacterial Activity of Opuntia ficus-indica Root Extracts from Algeria

The chemical composition, investigated by gas chromatography-mass spectrometry, and antibacterial activity of lipophilic extractives of three varieties of Opuntia ficus-indica roots from Algeria are reported in this paper for the first time. The results obtained revealed a total of 55 compounds, including fatty acids, sterols, monoglycerides and long chain aliphatic alcohols that were identified and quantified. β-Sitosterol was found as the major compound of the roots of the three varieties. Furthermore, considerable amounts of essential fatty acids (ω3, ω6, and ω9) such as oleic, linoleic, and linolenic acids were also identified. The green variety was the richest among the three studied varieties. The antibacterial activity, evaluated with disc diffusion method, revealed that lipophilic extracts were effective mainly against Gram-positive Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) (19~23 mm). Gram-negative strains mainly Pseudomonas aeruginosa gave an inhibition zone of 18 mm, which is considered high antibacterial activity. The minimal inhibitory concentrations of the tested bacteria revealed interesting values against the majority of bacteria tested: 75–100 µg mL⁻¹ for Bacillus sp., 250–350 µg/mL for the two Staphylococcus strains, 550–600 µg mL⁻¹ for E. coli, and 750–950 µg mL⁻¹ obtained with Pseudomonas sp. This study allows us to conclude that the lipophilic fractions of cactus roots possess interesting phytochemicals such as steroids, some fatty acids and long chain alcohols that acted as antibiotic-like compounds countering pathogenic strains.

Biocontrol of Wilt disease of rice seedlings incited by Fusarium oxysporum through soil application of Streptomyces chilikensis RC1830

The genus Streptomyces includes many antifungal metabolite producing novel strains. Fusarium oxysporum a soil-inhabiting pathogenic fungi, that affects rice to cause wilt disease. This work demonstrates the efficacy of novel Streptomyces chilikensis strain RC1830, previously isolated from estuarine habitat Chilika Lake in preventing the F. oxysporum wilting/root rot disease and promoting the growth of rice (Var. Swarna) seedlings. A total of 25 different compounds were identified from crude extracts of S. chilikensis RC1830 by GC-MS. In pot trial experiments, Streptomyces treated rice seedlings showed significantly reduced Disease severity index (DSI) by 80.51%. The seedlings growth parameters (root length, root fresh weight and root dry weight )were also increased by 53.91%, 62.5%, 73.46% respectively in Streptomyces treated groups of seedlings compared to Fusarium infected seedlings. Similarly, the shoot length, shoot dry weight and shoot fresh weight were also increased by 26%, 58% and 34.4% respectively in Streptomyces treated groups of seedlings compared to Fusarium infected seedlings. Formulations of the strain were prepared using seven organic & inorganic wastes as the carrier material and the shelf lives of the propagules were also monitored. Vermiculite and activated charcoal formulations stored at 4°C exhibited a higher viable cell count after 3 months of storage.

Use of Secondary Metabolites of Wood-Decaying Fungi to Reduce Damping off Disease

Phytopathogenic fungi can cause plant diseases that are difficult to control, including mass mortality of some tree species. The Fusarium oxysporum complex (sensu lato) is one of the most dangerous groups of phytopathogenic fungi, causing the death of conifer species, including Pinus sylvestris seedlings in forest and ornamental nurseries. Recently, non-chemical methods of plant protection have become the basis of integrated pest management (IPM) in the European Union (EC Directive). The possibility of protection of pine seedlings against the pathogen F. oxysporum using active substances from wood-destroying fungi commonly found in forests was examined. Methanolic extracts of Fomitopsis pinicola, Ganoderma applanatum, and Trametes versicolor were found to contain substances effective in both prevention and treatment of infected seedlings. G. applanatum and T. versicolor showed particular biological activity in increasing plant resistance. Efficacy, especially of the extract of F. pinicola, increased with concentration. Further field trials are needed to confirm the results obtained in laboratory tests on plant protection.

The Potential of Fatty Acids and Their Derivatives as Antifungal Agents: A Review

Fungal contamination presents several problems: in humans, health issues arise from infections with opportunistic filamentous fungi and yeast, while in food, fungi cause spoilage and, in particular, in the case of mycotoxigenic fungi, can cause serious health issues. Several types of fatty acids and their derivatives, oxylipins, have been found to have inhibitory effect towards fungal growth and the production of mycotoxins. The use of fatty acids as antifungals could fulfil consumer’s requests of more natural and environmentally friendly compounds, while being less likely to promote fungal resistance. In addition, due to their nature, fatty acids are easily used as food additives. In this work, we review the most relevant and recent studies on the antifungal ability of fatty acids. We focused on saturated fatty acids, unsaturated fatty acids, and oxylipins, their different impact on fungal inhibition, their proposed modes of action, and their ability to impair mycotoxin production. Applications of fatty acids as antifungals and their limitations are also addressed.

Anu taila, an herbal nasal-drop, suppresses mucormycosis by regulating host TNF-α response and fungal ergosterol biosynthesis

AIM

The intractable, mucormycosis, caused by Mucorales primarily targets immunocompromised individuals. The first-line therapy, intravenous liposomal Amphotericin B and surgical debridement of necrotic tissue, is contraindicative in individuals with compromised kidneys. This invokes a pressing need to identify safer treatment options.

METHODS AND RESULTS

Antifungal effect of the classical nasal drop, Anu taila, against Mucor spp. was investigated through microbiological, cytological, analytical chemical (HPLC and GS/MS/MS) and field emission scanning electron microscopic (FE-SEM) approaches. Anu taila pre-treated spores germinated late, resulting in reduced infectivity, observed as milder monocytic immune response. Conversely, Anu taila pre-treated THP-1 cells exhibited an improved immune response, through TNF-α, against Mucor spores. Repeated Anu taila application abolished fungal microarchitectures faster than Amphotericin B, evident from rapid replacement of hyphae, sporangiophores and sporangia with fused biomass, in the FESEM images. Anu taila downregulated sterol-C5-desaturase-coding ERG3 gene, crucial for ergosterol biosynthesis and resultant structural integrity, in Mucor spp.

CONCLUSION

Taken together, Anu taila was found effective against Mucor spp., with both prophylactic and curative implications, attributable to its phytochemical composition.

SIGNIFICANCE

Potential remedial effects of a classical nasal drop against an obdurate and challenging fungal infection are identified.

Marine Macroalgae, a Source of Natural Inhibitors of Fungal Phytopathogens

Fungal phytopathogens are a growing problem all over the world; their propagation causes significant crop losses, affecting the quality of fruits and vegetables, diminishing the availability of food, leading to the loss of billions of euros every year. To control fungal diseases, the use of synthetic chemical fungicides is widely applied; these substances are, however, environmentally damaging. Marine algae, one of the richest marine sources of compounds possessing a wide range of bioactivities, present an eco-friendly alternative in the search for diverse compounds with industrial applications. The synthesis of such bioactive compounds has been recognized as part of microalgal responsiveness to stress conditions, resulting in the production of polyphenols, polysaccharides, lipophilic compounds, and terpenoids, including halogenated compounds, already described as antimicrobial agents. Furthermore, many studies, in vitro or in planta, have demonstrated the inhibitory activity of these compounds with respect to fungal phytopathogens. This review aims to gather the maximum of information addressing macroalgae extracts with potential inhibition against fungal phytopathogens, including the best inhibitory results, while presenting some already reported mechanisms of action.

Fatty acid secretion by the white rot fungus, Trametes versicolor

Fungi can acquire and store nutrients through decomposing and converting organic matter into fatty acids. This research demonstrates for the first time that the white-rot fungus Trametes versicolor has the ability to secrete extracellular droplets which can contain a high concentration of long chain fatty acids and unsaturated fatty acids as well as monosaccharides and polysaccharides. The concentration and composition of the fatty acids varied according to the age of the droplet and the feedstock used for growth of the fungi. The results raise the possibility that these droplets could be harvested offering a new approach for the microbial generation of oil from waste.

Antifungal Effect of Triglycerol Monolaurate Synthesized by Lipozyme 435-Mediated Esterification

This study was designed to synthesize triglycerol monolaurate (TGML) with Lipozyme 435 as the catalyst, and explore its effects on the growth of Aspergillus parasiticus (A. parasiticus) and Aspergillus flavus (A. flavus) and the secretion of aflatoxin b1. The highest content of TGML (49.76%) was obtained at a molar ratio of triglycerol to lauric acid of 1.08, a reaction temperature of 84.93°C, a reaction time of 6 h and an enzyme dosage of 1.32%. After purification by molecular distillation combined with the washes with ethyl acetate and water, the purity of TGML reached 98.3%. Through characterization by electrospray-ionization mass spectrometry, infrared spectrum and nuclear magnetic resonance, the structure of TGML was identified as a linear triglycerol combined with lauroyl at the end. Finally, the inhibitory effects of TGML on the growths of A. parasiticus and A. flavus and the secretion of aflatoxin b1 were evaluated by measuring the colony diameter, the inhibition rate of mycelial growth and the content of mycotoxin in the media. The results indicated that TGML had a stronger inhibitory effects on colony growth and mycelial development of both toxic molds compared to sodium benzoate and potassium sorbate, and the secretions of toxins from A. parasiticus and A. flavus were completely suppressed when adding TGML at 10 and 5 mM, respectively. Based on the above results, TGML may be used as a substitute for traditional antifungal agents in the food industry.

Root Exudates Metabolic Profiling Suggests Distinct Defense Mechanisms Between Resistant and Susceptible Tobacco Cultivars Against Black Shank Disease

There is increasing evidence that root exudates play important roles in plant disease resistance. Black shank, caused by Phytophthora nicotianae, is a destructive soil-borne disease in tobacco (Nicotiana tabacum L.). The aim of the present study was to investigate the activity and composition of the root exudates from resistant and susceptible tobacco cultivars. The root exudates of the resistant cultivar Gexin 3 showed inhibitory activity against P. nicotianae, while the exudates of susceptible cultivar Xiaohuangjin 1025 stimulated the colony growth but had no effect on spore germination. Metabolic profiling using liquid chromatography/electrospray ionization-quadrupole-time-of-flight mass spectrometry depicted differing metabolic patterns of root exudates between Gexin 3 and Xiaohuangjin 1025. The activity and composition of root exudates was altered by P. nicotianae inoculation. Multivariate analysis showed that root exudates (including organic acids, alkaloids, fatty acids, and esters) were different between the two varieties. The defense substances in root exudates, such as tartaric acid, ferulic acid, and lauric acid, may represent a pre-infection prevention strategy for tobacco. Phenylpropanoids as well as inducers of salicylic acid, fatty acids, 6-hydroxyhexanoic acid, and hydrojasmonate may be involved in tobacco defense responses. Compared to the susceptible cultivar, the roots of the resistant cultivar exhibited high enzyme activities of phenylalanine ammonia-lyase, cinnamate-4-hydroxylase and 4-coumarate-CoA ligase, which may prompt the synthesis and secretion of phenylpropanoids. Our results indicated that the root exudates not only provide a pre-infection prevention strategy by exuding antimicrobial substances, but also increase tobacco disease resistance by eliciting plant defense responses. In addition, some defense compounds as well as compounds that play a role in inducing plant defense responses, showed potential for disease control application. This study provides an insight into possible disease resistance mechanisms of root exudates, and attempts the beneficial utilization of these secondary metabolites of plants.

Microflora of processed cheese and the factors affecting it

The basic raw materials for the production of processed cheese are natural cheese which is treated by heat with the addition of emulsifying salts. From a point of view of the melting temperatures used (and the pH-value of the product), the course of processed cheese production can be considered "pasteurisation of cheese." During the melting process, the majority of vegetative forms of microorganisms, including bacteria of the family Enterobacteriaceae, are inactivated. The melting temperatures are not sufficient to kill the endospores, which survive the process but are often weakened. From a microbiological point of view, the biggest contamination problem of processed cheese is caused by gram-positive spore-forming rod-shaped bacteria of the genera Bacillus, Geobacillus, and Clostridium. Other factors affecting the shelf-life and quality of processed cheese are mainly the microbiological quality of the raw materials used, strict hygienic conditions during the manufacturing process as well as the type of packaging materials and storage conditions. The quality of processed cheese is not only dependent on the ingredients used but also on other parameters such as the value of water activity of the processed cheese, its pH-value, the presence of salts and emulsifying salts and the amount of fat in the product.

Antimicrobial activities of ethanol and butanol fractions of white rose petal extract

White rose (Rosa hybrida) petals were extracted with ethanol (EtOH) or butanol (BuOH), and tested for their antimicrobial activities against two species of Gram-positive bacteria, six species of Gram-negative bacteria, and two species of fungi. On in vitro antimicrobial assays, Helicobacter pylori and Propionibacterium acnes were highly susceptible to white rose petal extract (WRPE)-EtOH and WRPE-BuOH, leading to minimal inhibitory concentrations of 100 and 10 μg/mL for H. pylori and 400 and 40 μg/mL for P. acnes, respectively. In in vivo experiments, C57BL/6 mice were infected with H. pylori by intragastric inoculation (1 × 10(8) CFU/mouse) 3 times, and orally treated twice a day for 14 days with WRPE-EtOH and WRPE-BuOH. On a CLO kit assay, 200 mg/kg of WRPE-EtOH fully eliminated the bacteria from the gastric mucosa, and the effect of 100 mg/kg of ethanol fraction was similar to pantoprazole (30 mg/kg), displaying 75% elimination. WRPE-BuOH was more effective, exhibiting 75% elimination at 20 mg/kg. The CLO test results were confirmed by bacterial identification. WRPE-EtOH and WRPE-BuOH inhibited the growth of various bacteria and fungi, and in particular, they effectively killed H. pylori and eliminated the bacteria from the mouse stomach. The results indicate that WRPE-EtOH and WRPE-BuOH could be good candidates for the elimination of H. pylori.

Diversity and antifungal activity of the endophytic fungi associated with the native medicinal cactus Opuntia humifusa (Cactaceae) from the United States

The endophytic fungal community associated with the native cactus Opuntia humifusa in the United States was investigated and its potential for providing antifungal compounds. A hundred-eight endophytic fungal isolates were obtained and identified by molecular methods into 17 different taxa of the genera Alternaria, Aureobasidium, Biscogniauxia, Cladosporium, Cryptococcus, Curvularia, Diaporthe, Epicoccum, Paraconiothyrium, Pestalotiopsis and Phoma. The most frequent species associated with O. humifusa were Alternaria sp. 3, Aureobasidium pullulans and Diaporthe sp. The fungal community of O. humifusa had a high richness and diversity; additionally, the species richness obtained indicates that the sample effort was enough to recover the diversity pattern obtained. Six extracts of endophytes showed antifungal properties and (1)H NMR analyses of the extracts of Alternaria sp. 5 Ohu 8B2, Alternaria sp. 3 Ohu 30A, Cladosporium funiculosum Ohu 17C1 and Paraconiothyrium sp. Ohu 17A indicated the presence of functional groups associated with unsaturated fatty-acid olefinic protons and fatty acid methylene and methyl protons. GC-FID analysis of these extracts confirmed the presence of a mixture of different fatty acids. The (1)H NMR analyses of Biscogniauxia mediterranea Ohu 19B extracts showed the presence of aromatic compounds. From the extract of B. mediterranea we isolated the compound 5-methylmellein that displayed moderate antifungal activity against the phytopathogenic fungi Phomopsis obscurans. Our results suggest that native medicinal cacti of the United States can live symbiotically with rich and diverse endophytic communities and may be a source of bioactive molecules, including those able to inhibit or control plant disease pathogens.

Sebaceous lipid profiling of bat integumentary tissues: quantitative analysis of free Fatty acids, monoacylglycerides, squalene, and sterols

White-nose syndrome (WNS) is a fungal disease caused by Pseudogymnoascus destructans and is devastating North American bat populations. Sebaceous lipids secreted from host integumentary tissues are implicated in the initial attachment and recognition of host tissues by pathogenic fungi. We are interested in determining if ratios of lipid classes in sebum can be used as biomarkers to diagnose severity of fungal infection in bats. To first establish lipid compositions in bats, we isolated secreted and integral lipid fractions from the hair and wing tissues of three species: big brown bats (Eptesicus fuscus), Eastern red bats (Lasiurus borealis), and evening bats (Nycticeius humeralis). Sterols, FFAs, MAGs, and squalene were derivatized as trimethylsilyl esters, separated by gas chromatography, and identified by mass spectrometry. Ratios of sterol to squalene in different tissues were determined, and cholesterol as a disease biomarker was assessed. Free sterol was the dominant lipid class of bat integument. Squalene/sterol ratio is highest in wing sebum. Secreted wing lipid contained higher proportions of saturated FFAs and MAGs than integral wing or secreted hair lipid. These compounds are targets for investigating responses of P. destructans to specific host lipid compounds and as biomarkers to diagnose WNS.

The influence of fat and monoacylglycerols on growth of spore-forming bacteria in processed cheese

Highly undesirable microbial contaminants of processed cheese are endospore-forming bacteria of the genera Bacillus and Clostridium. Survival of Bacillus subtilis, B. cereus, Clostridium butyricum and C. sporogenes was examined in model processed cheese samples supplemented with monoacylglycerols. In processed cheese samples, monoacylglycerols of undecanoic, undecenoic, lauric and adamantane-1-carboxylic acid at concentration of 0.15% w/w prevented the growth and multiplication of both Bacillus species throughout the storage period. The two species of Clostridium were less affected by monoacylglycerols in processed cheese samples and only partial inhibition was observed. The effect of milk fat content on microbial survival in processed cheese was also evaluated. The growth of Bacillus sp. was affected by the fat level of processed cheese while population levels of Clostridium sp. did not differ in processed cheese samples with 30, 40 and 50% fat in dry matter.

Potential antagonistic effects of nine natural fatty acids against Meloidogyne incognita

Fatty acids, the essential components of life, were widely present in various seed cakes, gutter oil, and other resources. The objective of this study was to evaluate the potential antagonistic effects of nine fatty acids (FAs) against Meloidogyne incognita (root-knot nematodes). The results showed that butyric, caprylic, capric, lauric, myristic, palmitic, and oleic acids significantly reduced M. incognita reproduction, whereas cucumber (Cucumus sativus) biomass was not adversely affected by the tested FAs and was even significantly increased in several fatty acids treatments. All nine tested fatty acids showed apparent inhibitory effects on egg hatching on day 21, especially capric acid with which the hatching rate was reduced to 15.8% as compared to that using sterile distilled water. Caproic, caprylic, capric, lauric, myristic, and palmitic acids caused significantly higher mortality of the second-stage juvenile of M. incognita than the other three FAs, and both caprylic and capric acids resulted in approximately 50% mortality (2000 μmol/L) after a 24 h exposure. In conclusion, fatty acids showed the nematicidal effect differently, among which capric acid showed a strong nematicidal effect and might be a powerful active substance for integrated M. incognita management. Given the general nematicidal properties of FAs, farmers might utilize waste resources, such as oil seed cake, gutter oil, etc., containing various FAs or use pure FAs for effective M. incognita management.

Natural resistance of rose petals to microbial attack

Petals of red, yellow and white roses (Rosa damascene Mill.) of the family Rosaceae were extracted with (1:1) methylene chloride/methanol and tested for their antimicrobial activities against four species of Gram-positive bacteria (Bacillus cereus, Bacillus subtilis, Micrococcus luteus and Staphylococcus aureus), five species of Gram-negative bacteria (Enterobacter aerogenes, Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa and Serratia marcescens) and five species of fungi (Penicillium notatum, Aspergillus niger, Rhizopus stolonifer, Saccharomyces cerevisiae and Fusarium oxysporum). All of the crude extracts showed a wide range of antimicrobial activities according to the tested organism and rose's type. Micrococcus luteus was found to be the most susceptible bacteria to all crude extracts. Red and yellow petal extracts showed much higher antibacterial activity than the white petals extract. Bacillus subtilis was found to be the least susceptible to all extracts. The fungus, Penicillium notatum was found to be the most susceptible with white petal extract being the most effective. Saccharomyces cerevisiae and Fusarium oxysporum were the least susceptible to all extracts. White roses extract showed much higher antifungal activities against Penicillium notatum than red or yellow roses, therefore, it was subjected to several bioassay guided chromatographic fractionations and purification to isolate the active chemical(s) responsible for the antifungal activity. Chemical structure of the isolated antifungal compounds were identified by spectroscopy techniques and found to be a γ-sitosterol and (Z,Z)-9,12-octadecadienoic acid. Antibacterial activity of the various types of rose extracts were due to complex mixtures of organic compounds which are still under chemical investigation and will be published later.

Metabolite composition and bioactivity of Rhizoctonia solani sclerotial exudates

Sclerotia are vegetative structures that play a major role in survival of fungi under adverse conditions. The sclerotia of the plant pathogen Rhizoctonia solani AG2-2 IIIB exude liquid brown droplets that were evaluated for their bioactivity and toxicity against microorganisms and plant species. Also, their metabolic composition was analyzed by integrating Fourier transform ion cyclotron resonance-mass spectrometry (FT-ICR/MS), gas chromatography-MS (GC/MS), and proton nuclear magnetic resonance ((1)H NMR) spectroscopy. The results showed that exudates are complex mixtures composed of phenolics (17.40%), carboxylic acids (12.79%), carbohydrates (6.08%), fatty acids (3.78%), and amino acids (3.47%). The presence of such metabolites contributed to their antifungal and phytotoxic activities. The biological interpretation of the results highly suggests that the exudates not only have multiple roles in fungal physiology but also are a potential bioactive source with moderate toxicity. Our findings show with certainty that the integration of different analytical platforms is a powerful approach for extracting the maximum and reliable information on the metabolic composition of complex biological samples.

Trypanocidal, leishmanicidal and antifungal potential from marine red alga Bostrychia tenella J. Agardh (Rhodomelaceae, Ceramiales)

Specimens of the red alga Bostrychia tenella J. Agardh (Rhodomelaceae, Ceramiales) were collected from the São Paulo coast and submitted to room temperature solvent extraction. The resulting extract was fractionated by partitioning with organic solvent. The n-hexane (BT-H) and dichloromethane (BT-D) fractions showed antiprotozoal potential in biological tests with Trypanosoma cruzi and Leishmania amazonensis and presented high activity in an antifungal assay with the phytopathogenic fungi Cladosporium cladosporioides and Cladosporium sphaerospermum. Chromatography methods were used to generate subfractions from BT-H (H01 to H11) and from BT-D (D01 to D19). The subfractions were analyzed by gas chromatography-mass spectrometry (GC/MS), and the substances were identified by retention index (Kovats) and by comparison to databases of commercial mass spectra. The volatile compounds found in marine algae were identified as fatty acids, low molecular mass hydrocarbons, esters and steroids; some of these have been previously described in the literature based on other biological activities. Moreover, uncommon substances, such as neophytadiene were also identified. In a trypanocidal assay, fractions BT-H and BT-D showed IC(50) values of 16.8 and 19.1 microg/mL, respectively, and were more active than the gentian violet standard (31 microg/mL); subfractions H02, H03, D01 and D02 were active against L. amasonensis, exhibiting IC(50) values of 1.5, 2.7, 4.4, and 4.3 microg/mL, respectively (standard amphotericin B: IC(50)=13 microg/mL). All fractions showed antifungal potential. This work reports the biological activity and identification of compounds by GC/MS for the marine red alga B. tenella for the first time.