Fungitoxic activity of Indian borage (Plectranthus amboinicus) volatiles

Indian borage (Plectranthus amboinicus) was investigated for antifungal activity through agar well diffusion assay. Indian borage oil (IBO) was found to be effective against various fungi tested, as it inhibited the radial growth of mycelia and exhibited broad fungitoxic properties against Aspergillus flavus, Aspergillus niger, Aspergillus ochraceus CFR 221, Aspergillus oryzae, Candida versatilis, Fusarium sp. GF-1019, Penicillium sp., and Saccharomyces cerevisiae. The effective concentration of IBO on the growth of A. ochraceus in yeast extract sucrose medium was determined. IBO completely inhibited ochratoxin (OTA) production by the toxigenic strain A. ochraceus at 500 ppm. Also, the application of IBO at 100 mg/g in food samples resulted in inhibition of the growth of A. ochraceus in food systems such as groundnut, maize and poultry feed and no detectable amount of OTA was found at a high moisture level of 30%, even after seven days. IBO has the potential for use as a botanical fungitoxicant against fungal attack in stored food commodities.     

Contamination with storage fungi of human food from Cameroon

In a mycological study, a total of 95 human food samples were investigated to evaluate the incidence of fungal contamination in Cameroon by conventional identification method and partly confirmed by DNA sequencing. The isolated fungal spp. were further studied to determine their toxigenic potentials. The investigation revealed the predominance of Aspergillus and Penicillium with 96% of samples contaminated with at least one species of these fungi, whereas the incidence of co-contamination of samples was 85%. Aspergillus flavus and Aspergillus parasiticus (Flavi section) were the most predominant species contaminating mainly maize and peanuts. In addition, P. crustosum and P. polonicum were the most common contaminants belonging to the genus Penicillium. On the other hand, A. ochraceus (Circumdati section) registered a low incidence rate of 5%, including other members of the Aspergillus group. Other members of the genera Rhizopus and Alternaria spp. were also registered in the study. A majority of fungal strains of A. ochraceus, A. parasiticus, P. crustosum and P. polonicum isolated were toxigenic, producing the mycotoxins tested for, while none was detected in cultures of A. fumigatus. The high incidence rate of fungi contamination coupled with their potentials in producing mycotoxins gives a strong indication that the samples tested may likely be contaminated with various mycotoxins. There is need for further study to assess the incidence of mycotoxins contamination in similar food samples.     

Assessment of Thymus vulgaris L. essential oil as a safe botanical preservative against post harvest fungal infestation of food commodities

A total of 14 odoriferous angiospermic essential oils were tested against the toxigenic strain of Aspergillus flavus. The essential oil of Thymus vulgaris L. showed highest antifungal efficacy. The thyme oil absolutely inhibited the mycelial growth of A. flavus at 0.7 μl ml^− 1 and exhibited a broad fungitoxic spectrum against eight different food contaminating fungi viz. Fusarium oxysporum, Cladosporium herbarum, Curvularia lunata, Aspergillus terreus, Aspergillus niger, Aspergillus fumigatus, Alternaria alternata and Botryodiploidia theobromae. The oil also showed significant antiaflatoxigenic efficacy as it completely arrested the aflatoxin B₁ production at 0.6 μl ml^− 1. Thyme oil as fungitoxicant was also found superior over most of the prevalent synthetic fungicides. The LC₅₀ of thyme oil against mice was recorded as 7142.85 μl kg^− 1 body weight indicating its non-mammalian toxicity and strengthening its safe exploitation as preservative for stored food commodities. The findings recommend the thyme oil as potential botanical preservative in eco-friendly control of biodeterioration of food commodities during storage.

Industrial relevance

The thyme essential oil may be recommended for large scale application as a plant based preservative for stored food items because of its strong antifungal as well as antiaflatoxigenic efficacy. Because of broad antimicrobial spectrum, more efficacy over prevalent synthetic preservatives as well as non-mammalian toxicity, the thyme essential oil may be formulated as a safe and economical plant based preservative against post harvest fungal infestation and aflatoxin contamination of food commodities.     

Assessment of Cymbopogon citratus (DC.) Stapf Essential Oil as Herbal Preservatives Based on Antifungal,Antiaflatoxin, and Antiochratoxin Activities and In Vivo Efficacy during Storage

Thirty‐five randomly collected samples of stored table grapes (Vitis vinifera L.) from different markets of Gorakhpur city, Uttar Pradesh, India, revealed occurrence of 11 types of fungi. Of which, Aspergillus flavus, Aspergillus niger, and Aspergillus ochraceus were dominant causing severe decay of grapes with 58%, 52%, and 67% incidence, respectively. On screening of 15 essential oils at 0.33 μL/mL, Cymbopogon citratus oil caused 100% mycelial inhibition against aforesaid dominant fungi. Oil was fungistatic at 0.29 μL/mL and exhibited broad fungitoxicity against other fruit rotting fungi associated with collected samples. C. citratus oil completely inhibited the growth and mycotoxin (AFB1 and OTA) secretion of the aflatoxigenic and ochratoxigenic strains of A. flavus, A. niger, and A. ochraceus at 0.8 μL/mL. E‐Citral (52.9%) and Z‐Citral (39.38%) were the major components of C. citratus oil during gas chromatography and gas chromatography‐mass spectrometry analysis. Application of 200 and 300 μL of C. citratus oil on 1 kg of stored grapes showed enhancement of shelf life up to 10 d. The oil did not exhibit any phytotoxic effect on fruits. These results confirm that C. citratus oil could be a natural alternative to commercial fungicide for control of fruit rotting fungi of stored grapes.     

In Vitro Determination of the Antifungal Activity of Artemisia campestris Essential Oil from Algeria

The chemical composition of the essential oil isolated from the aerial parts of Artemisia campestris from Algeria and its antifungal activity against 10 filamentous fungal strains were investigated. The A. campestris essential oil was obtained in a yield of 0.71% (v/w). The major constituents of the oil were α-pinene (18.65%), β-pinene (16.78%), β-myrcene (17.34%), and germacrene D (10.34%). Our study showed that A. campestris essential oil was a potent antifungal agent against some pathogenic fungal species. Fusarium graminearum was the most sensitive strain to A. campestris essential oil with minimal inhibitory concentration and minimal fungicidal concentration values of 1.25 µL/mL (v/v). The essential oil also exhibited a strong fungicidal activity against the tested fungi, except for Penicillium citrinum, P. viridicatum, and Aspergillus niger (MFC >20 µL/mL). Our findings suggested the application of A. campestris essential oil as a biofungicide in order to reduce the dependence on synthetic fungicides and ensure food safety and quality.     

Efficacy of Acorus calamus L. essential oil as a safe plant‐based antioxidant,Aflatoxin B1 suppressor and broad spectrum antimicrobial against food‐infesting fungi

The study explores the efficacy of Acorus calamus L. essential oil (EO) as a safe plant‐based broad spectrum antifungal, antiaflatoxin, antioxidant food additive. The oil completely inhibited the growth and toxin production of the toxigenic strain of Aspergillus flavus at 0.4 and 0.25 μL mL^?1, respectively. EO exhibited pronounced antifungal activity against sixteen food‐infesting fungal species at 0.5 μL mL^?1. The EO showed strong antioxidant efficacy (IC₅₀ 1.06 μL mL^?1) and nonphytotoxic nature on germination of chickpea seeds. The EO was found nonmammalian toxic showing high LD₅₀ (4877.4 μL kg^?1) for mice (oral, acute). The chemical profile of EO was determined through GC and GC–MS analysis. The findings strengthen the possibility of A. calamus EO as a plant‐based food additive in view of its favourable safety profile, antioxidant and antiaflatoxigenic efficacy and broad spectrum antimicrobial activity against food‐infesting fungi.     

Fermentation of table cream by Lactobacillus plantarum strains: effect on fungal growth,aflatoxin M1 and ochratoxin A

Aflatoxin M1 (AFM₁) and ochratoxin A (OTA) are two main mycotoxins in milk and dairy products. In the present work, the ability of four Lactobacillus strains (L. plantarum PTCC 1058, L. plantarum LP3, L. plantarum AF1 and L. plantarum LU5) to remove AFM1 and OTA in fermented cream was studied during 24 h fermentation. The antifungal activity of the mentioned lactobacilli against the defined fungi (Aspergillus flavus PTCC 5004, Aspergillus parasiticus PTCC 5018, Aspergillus nidulans PTCC 5014, Aspergillus ochraceus PTCC 5060) was also evaluated. The results showed that the cell counts of all strains were increased by 64–70% during fermentation. All Lactobacillus strains decreased the amount of AFM₁ significantly (P ≤ 0.05) in the range of 26–52%, which the highest AFM₁-reducing effect was related to L. plantarum LU5 (from 0.5 to 0.24 μg kg⁻¹). The mean OTA removal by Lactobacillus strains in fermented cream also ranged from 32 to 58%. Amongst Lactobacillus strains, the cell-free culture supernatants of L. plantarum LU5 showed the highest (inhibition zone of 26.7 ± 1.2 mm) and L. plantarum LP3 and L. plantarum PTCC 1058 the lowest antifungal activities. The fermented creams contained Lactobacillus strains exhibited the highest and lowest antifungal activities against A. ochraceus and A. parasiticus, respectively. L. plantarum LU5, with the inhibition zone of 27.6 ± 0.9 mm, was the most effective fungal inhibitor, while L. plantarum PTCC 1058 had the lowest antifungal activity.     

Production and Characterization of an Antifungal Compound (3-Phenyllactic Acid) Produced by <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> Strain

The Lactobacillus plantarum strain was isolated from grass silage that produces a broad spectrum of antifungal compound, active against food and feed-borne filamentous fungi in agar plate assay. Aspergillus fumigatus and Rhizopus stolonifer were the most sensitive among molds. No inhibitory activity could be detected against mold Penicillium roqueforti. Enhanced antifungal activity was observed at 30 °C in pH 6.5. Minimum inhibitory concentration values against fungal cultures were ranged from 6.5 to 12.0 mg/ml for commercial 3-phenyllactic acid. The production of antifungal compound phenyllactic acid (PLA), lactic acid, and acetic acid by L. plantarum strain was also investigated. Structure characterization of the antifungal compound was carried out by nuclear magnetic resonance spectroscopy, infrared spectroscopy, and gas chromatography. The produced compound (PLA) acted as a fungistatic and delayed the growth of a variety of fungal contaminants.     

Chemical composition of Ocimum basilicum L. essential oil and its efficacy as a preservative against fungal and aflatoxin contamination of dry fruits

The study presents fungal and aflatoxin contamination of some dry fruits and Ocimum basilicum essential oil (EO) as a plant‐based preservative. During mycoflora analysis, 2045 fungal isolates were recorded from dry fruits and 40% isolates of Aspergillus flavus were toxigenic in nature. The EO of O. basilicum exhibited strong fungitoxicity against toxigenic strain of A. flavus. Its minimum inhibitory concentration (MIC) was recorded at 1.0 μL ml^?1, and it completely inhibited aflatoxin B₁ production at 0.5 μL ml^?1. The oil exhibited broad fungitoxic spectrum and considerably reduced A. flavus isolates from dry fruits when used as fumigant in closed storage containers at 1.0 μL ml^?1. The chemical profile of the EO was standardised through GC–MS analysis. Based on antifungal potency, antiaflatoxigenicity and efficacy as fumigant during storage conditions, O. basilicum EO may be recommended as a botanical preservative for enhancing the shelf life of dry fruits and edible products during storage.     

Antifungal,antiaflatoxin and antioxidant potential of chemically characterized Boswellia carterii Birdw essential oil and its in vivo practical applicability in preservation of Piper nigrum L. fruits

The study explores the chemical profile, antimicrobial and antioxidant activity of Boswellia carterii essential oil (EO). The EO significantly inhibited growth and aflatoxin production by the food borne toxigenic strain of Aspergillus flavus at 1.75 μl/ml and 1.25 μl/ml respectively. It exhibited broad fungitoxic spectrum against 12 food borne moulds and also showed strong antioxidant activity, IC₅₀ value and % inhibition of linoleic acid peroxidation being 0.64 μl/ml and 51.68% respectively. The antifungal action of EO was observed in terms of reduction in ergosterol content of plasma membrane of A. flavus. As fumigant in food system in storage containers, the EO provided 65.38% protection against fungal deterioration of Piper nigrum. GC–MS results revealed 31 components of EO. The chemically characterized B. carterii EO may thus be recommended as plant based preservative in view of its antifungal, antiaflatoxigenic, antioxidant activity and efficacy in food system.     

Promising antifungal effect of some Euro-Asiatic plants against dangerous pathogenic and toxinogenic fungi

BACKGROUND: Increasing evidence of fungicide‐resistant toxinogenic and pathogenic fungal species is obvious. Looking for new possibilities of antifungal treatment or sources of antifungal substances is a major problem. Some medicinal plants exert strong antifungal properties and could be conveniently used as a promising alternative source for presently problematic antifungal treatment in many areas with respect to their natural origin. Methanol extracts of 46 medicinal plants from the Eurasian area were used in a screening assay for antifungal activity in this study. The growth inhibitory effect was tested against six significant pathogenic and toxinogenic fungal species: Fusarium oxysporum, F. verticillioides, Penicillium expansum, P. brevicompactum, Aspergillus flavus and A. fumigatus. RESULTS: For 14 plant species, the possibility of using them as natural fungicides was indicated. The extract from Grindelia camporum showed significant activity against all target fungal species. The most sensitive target fungus was the toxinogenic and human pathogenic species A. fumigatus. CONCLUSION: This study has identified 14 extracts of medicinal plants with a potential use as an antifungal treatment in various areas. One of them showed promising efficiency against all selected significant pathogenic and toxinogenic fungal species. Copyright © 2010 Society of Chemical Industry     

Evaluation of chemically characterised essential oils of Coleus aromaticus,Hyptis suaveolens and Ageratum conyzoides against storage fungi and aflatoxin contamination of food commodities

The result of the present investigation explores the efficacy of chemically characterised essential oils (EOs) of Coleus aromaticus, Hyptis suaveolens and Ageratum conyzoides as antifungal and antiaflatoxigenic agent against some storage fungi and the toxigenic strain of Aspergillus flavus (Saktiman 3NSt). Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of these EOs were also determined against the toxigenic strain of A. flavus (Saktiman 3NSt). The EO from C. aromaticus was found to be most effective exhibiting MIC and MFC at 0.1μL mL^?1. The EOs also completely checked aflatoxin B₁ synthesis in concentration‐dependent manner. In addition, fumigation of stored wheat samples with EOs exhibited remarkable protection (>80%) from fungal infestation showing their efficacy during in vivo storage conditions. Based on the results of the present investigation, the EOs of C. aromaticus, H. suaveolens and A. conyzoides may be recommended as novel plant‐based antifungal and aflatoxin B₁ suppressor over the synthetic preservatives.     

Tannic acid modulated the wall compactness of cinnamaldehyde-loaded microcapsules and enhanced inhibitory effect on Aspergillus brasiliensis

The evaluation of antifungal properties in cinnamaldehyde (CA)-loaded microcapsules is significant to clarify potential food applications in various food matrices and systems. The impact of tannic acid (TA) crosslinking on the release and the antifungal properties of CA microcapsules was investigated based on gelatin/gum Acacia complex coacervates. The inhibition zone diameter of microencapsulated CA against Aspergillus brasiliensis was dependent on the TA addition and retained 26.1 ± 0.1 mm after 180-day storage at 25 °C. Specifically, TA enhanced hydrogen bond interactions between the microcapsule wall materials and favoured a sustained release of CA during the incubation with Aspergillus brasiliensis. Meanwhile, confocal laser scanning microscopic observation revealed that the microstructure of multinuclear microcapsules was more compact and intact under the crosslinking of 0.4% TA. The comparation of microscopic morphology and membrane potential of Aspergillus brasiliensis exerted a synergistic antifungal effect between CA and TA crosslinked microcapsules.     

Efficacy of Some Essential Oils Against Aspergillus flavus with Special Reference to Lippia alba Oil an Inhibitor of Fungal Proliferation and Aflatoxin B1 Production in Green Gram Seeds during Storage

During mycofloral analysis of green gram (Vigna radiata (L.) R. Wilczek) seed samples taken from different grocery stores by agar and standard blotter paper methods, 5 fungal species were identified, of which Aspergillus flavus exhibited higher relative frequency (75.20% to 80.60%) and was found to produce aflatoxin B₁. On screening of 11 plant essential oils against this mycotoxigenic fungi, Lippia alba essential oil was found to be most effective and showed absolute inhibition of mycelia growth at 0.28 μL/mL. The oil of L. alba was fungistatic and fungicidal at 0.14 and 0.28 μL/mL, respectively. Oil had broad range of fungitoxicity at its MIC value and was absolutely inhibited the AFB1 production level at 2.0 μL/mL. Chemical analysis of this oil revealed geranial (36.9%) and neral (29.3%) as major components followed by myrcene (18.6%). Application of a dose of 80 μL/0.25 L air of Lippia oil in the storage system significantly inhibited the fungal proliferation and aflatoxin production without affecting the seed germination rate. By the virtue of fungicidal, antiaflatoxigenic nature and potent efficacy in storage food system, L. alba oil can be commercialized as botanical fungicide for the protection of green gram seeds during storage.     

ANTIFUNGAL ACTIVITIES OF THYME, CLOVE AND OREGANO ESSENTIAL OILS

The antifungal potential of essential oils of oregano (Origanum vulgare), thyme (Thymus vulgaris) and clove (Syzygium aromaticum) was determined. To establish this antifungal potential, two molds related to food spoilage, Aspergillus niger and Aspergillus flavus, were selected. The agar dilution method was employed for the determination of antifungal activities. The three essential oils analyzed presented inhibitory effects on both molds tested. Oregano essential oil showed the highest inhibition of mold growth, followed by clove and thyme. Aspergillus flavus was more sensitive to thyme essential oil than A. niger. Clove essential oil was a stronger inhibitor against A. niger than against A. flavus.     

Exploration of Islamic medicine plant extracts as powerful antifungals for the prevention of mycotoxigenic Aspergilli growth in organic silage

BACKGROUND: Feed contamination with mycotoxins is a major risk factor for animals and humans as several toxins can exist as residues in meat and milk products, giving rise to carry‐over to consumers via ingestion of foods of animal origin. The starting point for prevention, in this chain, is to eliminate the growth of mycotoxigenic fungi in the animal forage. Ten plant extracts, recommended in Islamic medicine, were evaluated as antifungal agents against mycotoxigenic Aspergilli, i.e. Aspergillus flavus and A. ochraceus, growth in organic maize silage. RESULTS: Most extracts had remarkable antifungal activities using both qualitative and quantitative evaluation methods. Cress (Lepidium sativum) seed extract was proven to be the most powerful among the plants examined. Blending of the most effective extracts (garden cress seed, pomegranate peel and olive leaf extracts), individually at their minimal fungicidal concentrations, with maize silage resulted in the reduction of inoculated A. flavus colony counts by 99.9, 99.6 and 98.7%, respectively, whereas silage blending with the combined extracts completely prohibited fungal growth for up to 30 days of incubation under aerobic conditions. CONCLUSION: Besides the health promoting effects, silage blending with the bioactive plant extracts examined could lead to the required protection from pathogenic and mycotoxigenic fungi. Copyright © 2011 Society of Chemical Industry     

Production of fungal enzymes and proteins from high salt cheese wheys

A fermentation procedure using wheys from buffalo milk, sweet rennet and salted wheys containing up to 15% NaC1, and based on the selection of salt-tolerant fungal cultures for production of microbial proteins and some economically important enzymes, is described. Certain strains of Aspergillus flavus, A. niger, A. ochraceus and A. terreus gave yields of mycelium ranging between 1.5 and 30 g on a dry weight basis. Strong proteolytic activities were exhibited by A. ochraceus, A. flavus and, to a lesser extent, by A. niger in the presence of salt up to 10% as final concentration. Powerful milk-clotting activities were also detected in culture supernatants of A. flavus and A. ochraceus. Extracellular β-galactosidases were released in to the culture fluids of these fungal strains with variable activities, depending upon the salt content of the growth medium. The application of the procedure is discussed.     

Impact of non-selective fungicides on the growth and production of ochratoxin A by Aspergillus ochraceus and A. carbonarius in barley-based medium

The aim of this study was to assess the influence of the non-selective fungicides mancozeb, copper oxychloride, and sulfur on the growth and capability for producing ochratoxin A (OTA) of ochratoxigenic isolates of Aspergillus carbonarius and A. ochraceus in barley-based medium. Lag phases and growth rates were determined for each fungicide at different doses, at 15°C and 25°C and at 0.97?a_w . Mancozeb at 40?mg?l^?1 inhibited fungal growth and provided lag phases >24 days at 10–20?mg?l^?1 and 15°C. OTA was observed only at 25°C and doses <10?mg?l^?1. At 15°C, copper oxychloride proved inhibitory at 800?mg?l^?1, while at 25°C growth was not delayed and only high doses decreased OTA levels. Sulfur was inhibitory or provided large lag phases at 5–8?g?l^?1 (at 15°C) while at 25°C growth took place even at 8?g?l^?1, although OTA levels were low or undetectable. The antifungal activity decreased in the order mancozeb?>?copper oxychloride?>?sulfur, and was lower at 25°C than at 15°C. OTA accumulation was affected by the type of fungicide, dose, temperature and time. The efficacy of these fungicides on the growth of A. carbonarius and A. ochraceus and OTA production in barley-based medium is assessed for the first time.     

2-Hydroxy-4-methoxybenzaldehyde inhibits the growth of Aspergillus flavus via damaging cell wall,cell membrane,manipulating respiration thus creating a promising antifungal effect on corn kernels

This study investigated the antifungal activity and the potential antifungal mechanisms of 2-hydroxy-4-methoxybenzaldehyde (HMB) against Aspergillus flavus (A. flavus). The minimum inhibitory concentration (MIC) of HMB in preventing spore germination was 70 μg mL⁻¹. HMB at MIC disrupted cell wall integrity by reducing the number of septa by 86.66% (P < 0.05) in mycelia and increased cell membrane permeability by about 14-fold (P < 0.05) evidenced by propidium iodide (PI) staining. Furthermore, HMB at MIC inhibited respiration by 33.33%. These results revealed that the antifungal activity of HMB against A. flavus could be attributed to the damaged cell wall integrity, cell membrane permeability and respiration metabolism. What’s more, A. flavus was completely restrained in corn kernels due to HMB. Therefore, HMB could be applied as an effective antifungal agent.     

Effect of formulated zimmu (Allium cepa L. × Allium sativum L.) extract in the management of grain mold of sorghum

BACKGROUND: The in vitro antifungal activity of zimmu (Allium cepa L. × Allium sativum L.) extract against Aspergillus flavus Link., Fusarium moniliforme Sheld, Curvularia lunata (Wakker) Boedijn and Alternaria alternata (Fr.) Keissler, the fungi associated with grain mold of sorghum, was evaluated. An emulsifiable concentrate (EC) formulation of zimmu extract was prepared and its efficacy in controlling grain mold was tested under field conditions. RESULTS: The leaf extract of zimmu exhibited strong antifungal activity against A. flavus, F. moniliforme, C. lunata and A. alternata and caused in vitro fungal growth inhibition of 73.3%, 71.1%, 70.0% and 74.4%, respectively. Foliar application of zimmu formulation 50 EC at 3 mLL^?1 (v/v) concentration 60, 75 and 90 days after sowing significantly reduced the incidence of grain mold and increased the grain weight and grain hardness. A significant reduction in the aflatoxin B1 content in sorghum grains was observed when sorghum plants were sprayed with zimmu formulation 50 EC at 0.3% concentration. Western blot analysis revealed that a thaumatin‐like protein (TLP) a molecular mass of 23 kDa that cross‐reacted with zeamatin antiserum was expressed at higher levels in sorghum grains after treatment with zimmu formulations. CONCLUSION: The leaf extract of zimmu exhibited antifungal activity against sorghum grain mold fungi. The formulated zimmu extract was significantly effective in reducing the grain mold incidence in sorghum under field conditions. This formulated zimmu extract offers a novel alternative for eco‐friendly management of grain mold of sorghum. Copyright © 2007 Society of Chemical Industry