Reduction In Fungal Growth Research Articles

Adenophora triphylla var. japonica Inhibits Candida Biofilm Formation, Increases Susceptibility to Antifungal Agents and Reduces Infection.

(1) Background: Candida is the most common cause of fungal infections worldwide, but due to the limited option of antifungal therapies, alternative strategies are required. (2) Methods: Adenophora triphylla var. japonica extract was used for the biofilm formation assay using RPMI1640. The combinatorial antifungal assay, the dimorphic transition assay, and the adherence assay were done to see the influence of inhibition of biofilm formation. qRT-PCR analysis were performed to check the gene expression. (3) Results: Adenophora triphylla var. japonica extract inhibited the Candida biofilm formation. Treatment of extract increased the antifungal susceptibility of miconazole from a 37% reduction in fungal growth to 99.05%, and also dose-dependently reduced the dimorphic transition of Candida and the attachment of Candida to HaCaT cells. The extract blocked the expression of hyphal-related genes, extracellular matrix genes, Ras1-cAMP-PKA pathway genes, Cph2-Tec1 pathway gene, and MAP kinase pathway gene. (4) Conclusions: In this study, the treatment of Adenophora triphylla var. japonica extract showed inhibition of fungal biofilm formation, activation of antifungal susceptibility, and reduction of infection. These results suggest that fungal biofilm formation is a good target for the development of antifungal adjuvants, and Adenophora triphylla var. japonica extract should be a good candidate for biofilm-associated fungal infections.

Effect of heat treatment and γ-irradiation on pasting, rheological, and fungal load of whole and dehulled millets.

Millets are important food crops in food systems and application of physical treatments could improve the functional properties of millet-based products. Therefore, we investigated the effect of heat and γ-irradiation treatments on the pasting, rheological, and microbial load of whole and dehulled millets (sorghum, foxtail millet, and pearl millet). Moreover, similarity in treatment effect was evaluated by principal component analysis (PCA). The results revealed the significant (p < 0.05) decrease in pasting properties of whole and dehulled millets, except for pasting temperature (71.03 to 74.88 °C). Likewise, significantly (p < 0.05) decreased tendency was observed for all rheological properties, except for phase angle (0.05 to 0.30°) and yield point (13 to 5089). Samples showed a significant (p < 0.05) reduction in fungal growth (89.75 × 104 to 4.46 × 104 CFU/g) compared to control (110.30 × 104 CFU/g). Moreover, samples individually formed 3 clusters (clusters 1: sorghum, 2: pearl millet, and 3: foxtail millet) based on pasting properties, which was confirmed by PCA. Therefore, the findings concluded that the effect of heat and γ-irradiation would be necessary to decrease pasting, rheological, and no microbial growth characteristics of dehulled and whole millets for the development of specific millet-based food products.

Studies of Penicillium species associated with blue mold disease of grapes and management through plant essential oils as non-hazardous botanical fungicides

Abstract Blue mold caused by Penicillium species is a major fungal disease threatening the viticulture industry in Pakistan, responsible for deteriorating the quality of grapes during handling, transportation, and distribution. Identification-based approaches of Penicillium species provide a better strategy on accurate diagnosis and effective management. In this study, 13 isolates were recovered from symptomatic grape bunches at five main fruit markets of Rawalpindi district, Punjab province. Based on morphological data and multi-loci phylogenetic analysis, the isolates were identified as two distinct species viz. Penicillium expansum (eight isolates) and Penicillium crustosum (five isolates). Meanwhile, the pathogenicity test of Penicillium isolates presented by the inoculation of grape bunches showed various degrees of severity. For improving the fruit quality and eliminating the needs of synthetic fungicides, botanicals such as thyme (Thymus vulgaris L.), fennel (Foeniculum vulgare L.), garlic (Allium sativum L.), ginger (Zingiber officinale L.), and carum (Carum capticum L.) essential oils (EOs) at concentrations of 0.6, 0.9, 1.2, and 1.5 mg/mL were evaluated. In vitro studies indicated that thyme EO showed a highly significant reduction of fungal growth. Furthermore, the experiments related to reducing the decay development and average weight loss percentage of grapes revealed similar findings. Based on the results of this study, it is recommended that thyme EO can be used as an eco-friendly botanical fungicide against Penicillium spp. causing blue mold disease.

Efficiency of Hydroxycinnamic Phenolic Acids to Inhibit the Production of Ochratoxin A by Aspergillus westerdijkiae and Penicillium verrucosum.

Ochratoxin A (OTA) is one of the worldwide most important mycotoxins in terms of health and agroeconomic consequences. With the aim to promote the use of phytochemicals as alternatives to synthetic fungicides, the effect of hydroxycinnamic acids on the fungal growth and OTA yield by two major OTA-producing species was investigated. After a first step dedicated to the definition of most suitable culture conditions, the impact of 0.5 mM ferulic (FER), p-coumaric (COUM), caffeic and chlorogenic acids was evaluated on Aspergillus westerdijkiae and Penicillium verrucosum. Whereas no fungal growth reduction was observed regardless of the phenolic acid and fungal isolate, our results demonstrated the capacity of FER and COUM to inhibit OTA production. The most efficient compound was FER that led to a 70% reduction of OTA yielded by P. verrucosum and, although not statistically significant, a 35% inhibition of OTA produced by A. westerdijkiae. To further investigate the bioactivity of FER and COUM, their metabolic fate was characterized in fungal broths. The capacity of P. verrucosum to metabolize FER and COUM through a C2-clivage type degradation was demonstrated. Overall, our data support the potential use of FER to prevent OTA contamination and reduce the use of synthetic pesticides.

Uncovering the biofumigant capacity of allyl isothiocyanate from several Brassicaceae crops against Fusarium pathogens in maize

Driven by environmental concerns, chemical fumigants are no longer allowed in many countries. Therefore, other strategies for reducing fungal inoculum in soils and on crop debris are being explored. In the present study, several Brassicaceae crops were screened for their potential to control Fusarium gramineaum and Fusarium poae mycelial growth in an in vitro inverted Petri dish experiment. Volatile production was measured using gas chromatography-mass spectrometry headspace analysis. A selection of cultivars from each crop species was further investigated using a pot experiment with maize. Ethiopian mustard (Brassica carinata) and brown mustard (Brassica juncea) released volatile allyl isothiocyanate (AITC) and a higher concentration of AITC was correlated with a better fungal growth reduction in the in vitro screening. Brown mustard cultivar Etamine completely inhibited growth of both Fusarium spp. Pure AITC in a solution with methanol resulted in a sigmoid dose-response curve for both Fusarium spp. tested. Fusarium poae appeared to be more tolerant to AITC than F. graminearum. A pot experiment revealed that the incorporation of brown mustard plant material could alleviate the clear negative effect of F. graminearum infection on maize growth. The present study demonstrated the correlation between the fungistatic effect of biofumigation crops on Fusarium spp. and their production of volatile AITC in vitro, without the addition of exogenous enzymes, and confirmed the biofumigation potential of brown mustard in a pot experiment with maize. These results may help farmers when selecting a green manure crop suitable for biofumigation. © 2020 Society of Chemical Industry.

Cold sub-atmospheric and atmospheric pressure plasma for the treatment of Trichophyton rubrum onychomycosis: An in-vitro study.

Previous studies have suggested the applicability of cold atmospheric pressure plasma for the treatment of onychomycosis. Whether delivering cold plasma in sub-atmospheric pressure would be beneficial for this purpose is yet to be established. The current study aimed to evaluate efficacy of cold sub-atmospheric and atmospheric pressure plasma in Trichophyton rubrum growth inhibition. Bovine nails infected with T. rubrum were treated by a cold air plasma device, which enables utilizing plasma in sub-atmospheric pressures (Low = 100 millibar; High = 300 millibar) or atmospheric pressure. The infected foci were exposed to the plasma source directly or indirectly. Treatment with high sub-atmospheric pressure setting achieved T. rubrum growth reduction of 94.0% and 73.0%, for direct and indirect exposure to the plasma source, respectively (P < .001). Low sub-atmospheric pressure setting achieved similar T. rubrum growth reduction of 86.2% for direct exposure to the plasma source (P < .001), but only marginally significant 58.8% reduction rate for indirect exposure to the plasma source (P = .056). None statistically significant fungal growth reduction was attained with the use of atmospheric pressure setting. Cold plasma was shown to effectively inhibit T. rubrum nail growth, with sub-atmospheric pressure setting achieving better outcome than atmospheric pressure.

Recyclable antimicrobial sulphonated poly (ether ether ketone) – copper films: Flat vs micro-pillared surfaces

The existence of bacteria and fungi on surfaces can be a serious threat to health causing numerous infections. With these microorganisms developing resistance over the years, there is an increasing need to develop surfaces that can kill or inhibit the growth of bacteria and fungi. In this work, we report the fabrication of sulphonated poly (ether ether ketone) (SPEEK) and its copper composite films as promising antimicrobial materials and investigated the effects of fabricating surface structures (micro-pillars) on the films. The fabricated films were systematically characterized and it was observed that both SPEEK and SPEEK – Cu films possessed antimicrobial properties which initially killed all of E. coli within 15 min of contact. Over longer times, as the films aged, the SPEEK – Cu film still achieved over 2 log (for flat film) and 4 log (for micro-pillared film) reduction of E. coli within 1 h of contact and it showed significant fungal growth reduction for Saccharomyces cerevisiae (yeast) and Aspergillus niger with 2 h of contact. Micro-pillared films had a larger water contact angle (131°) in comparison to flat films (64°) which thus rendered it hydrophobic. It was also observed that these micro-pillared films showed better antimicrobial properties and better copper release than flat as a result of better exposure of copper particles on the top surface of micro-pillars. The fabricated films were also thermally stable and exhibited tensile strengths ranging from 50 to 160 MPa depending on the surface morphology and copper content. Furthermore, the films were found to be recyclable by dissolution in sulphuric acid and re-casting to form new films with replenished sulphonic acid groups in the polymer matrix and restored antimicrobial properties.

Evaluation of Glycine max and Glycine soja for Resistance to Calonectria ilicicola

Breeding for resistance to soybean red crown rot (Calonectria ilicicola) has long been hampered by the lack of genetic sources of adequate levels of resistance to use as parents. Mini core collections of soybean (Glycine max) originating from Japan (79 accessions), from around the world (80 accessions), and a collection of wild soybeans (Glycine soja) consisting 54 accessions were evaluated for resistance to C. ilicicola (isolate UH2-1). In the first two sets, average disease severity scores of 4.2 ± 0.28 and 4.6 ± 0.31 on a rating scale from zero for no symptom to 5.0 for seedling death were recorded from the set from Japan and the world. No high levels of resistance were observed in these two sets. On the other hand, disease severity score of 3.8 ± 0.35 for the wild soybean accessions was somewhat lower and exhibited higher levels of resistance compared to the soybean cultivars. Three accessions in the wild soybean collection (Gs-7, Gs-9, and Gs-27) had disease severity score ≤2.5 and showed &gt;70% reduction in fungal growth in the roots compared to soybean control cv. “Enrei”. Further analysis using 10 C. ilicicola isolates revealed that accession Gs-9 overall had a wide range of resistance to all isolates tested, with 37% to 93% reduction in fungal growth relative to the cv. Enrei. These highly resistant wild soybean lines may serve as valuable genetic resources for developing C. ilicicola-resistant soybean cultivars.

Selection and Evaluation of Staphylococcus xylosus as a Biocontrol Agent against Toxigenic Moulds in a Dry-Cured Ham Model System.

Toxigenic moulds can develop on the surface of dry-cured meat products during ripening due to their ecological conditions, which constitutes a risk for consumers. A promising strategy to control this hazard is the use of antifungal microorganisms usually found in these foods. However, to date, the effectiveness of gram-positive catalase-positive cocci (GCC+) has not been explored. The aim of this work was to select GCC+ isolates with antifungal activity to study its effectiveness in a dry-cured ham model system at the environmental conditions reached during the ripening. Forty-five strains of GCC+ were evaluated and the isolate Staphylococcus xylosus Sx8 was selected to assess its efficacy at two different concentrations (106 and 104 cfu/mL) against Penicillium nordicum, Aspergillus flavus, Aspergillus parasiticus, and Penicillium griseofulvum at 15, 20, and 25 °C. The results showed that the inoculation of 106 cfu/mL of S. xylosus completely inhibited the growth of most fungi. In addition, in the presence of this strain at 104 cfu/mL, a significant reduction in fungal growth and mycotoxins production was observed at the three temperatures studied. In conclusion, S. xylosus Sx8 possesses great potential as a biological agent to control toxigenic moulds in dry-cured meat products.

Antifungal Activity of Copper, Zinc and Potassium Compounds on Mycelial Growth and Conidial Germination of Fusarium solani f. sp. piperis

Fusariosis is a disease that causes economic damage to black pepper (Piper nigrum L.) producers. Despite being a major disease, there is no record of efficient chemical control. Thus, the objective was to evaluate the antifungal activity of copper, zinc and potassium compounds in mycelial growth and conidial germination of Fusarium solani f. sp. piperis in vitro. For inoculation in PDA (Potato Dextrose Agar) medium, 7 mm discs from the pure culture were transferred to Petri dishes. The plates were incubated at 25ºC in a biochemical oxygen demand (BOD) chamber, with photoperiod of 12 h, for 15 days. Micronutrients were supplied as sulfates, CuSO4 (copper sulfate) and ZnSO4 (zinc sulfate), at concentrations of 1, 5, 10, 15 and 20 mmol/L. Potassium macronutrient (K) was supplied as KCl (potassium chloride) at concentrations of 30, 60, 90,120 and 150 mmol/L. The experiment was performed using a completely randomized design with 6 treatments and ten replications. CuSO4 showed fungicidal effect at concentrations of 10, 15 and 20 mmol/L. For ZnSO4 mycelial growth was completely inhibited at concentrations of 15 and 20 mmol/L. There was no inhibition or reduction of fungal growth in the presence of K. Copper and zinc at minimal concentrations were efficient in controlling mycelial growth and inhibition of spore germination of F. solani f. sp. piperis. In contrast, potassium did not exert fungicidal or fungistatic effect on the fungus.

Changes of antioxidant enzymes in ‘Thomson-Navel’ orange during induction of resistance to green mold (Penicillium digitatum (Pers.) Sacc.) as provoked by jasmonic acid, epibrassinolide, chitosan and cinnamon essential oil

Pathogenic agents are one of the causes of post-harvest citrus fruit loss. Therefore, the aim of this study was to evaluate the effect of post-harvest treatments with jasmonic acid (ja), epibrassinolide (epiBL), chitosan (chi) and cinnamon essential oil (cin) on induction of resistance to the citrus green mold (Penicillium digitatum (Pers.) Sacc.) and reduction of fungal growth by improving the activity of some antioxidant enzymes in ‘Thomson-Navel’orange. For this purpose, a factorial experiment was conducted in a completely randomized design. Treatments included positive and negative control, jasmonic acid (5, 10, 20 and 40 μl l-1), epibrassinolide (1, 4, 7 and 10 μmol l-1), chitosan (2.5, 5, 7.5 and 10 g l-1) and cinnamon essential oil (250, 500, 750 and 1000 ppm). Characteristics such as lesion diameter and activities of antioxidant enzymes including SOD, APX, CAT and POD were evaluated for a period of 96 hours with 24 hour intervals. The results indicated that all treatments significantly decreased the lesion diameter of fruits. Consequently, chitosan treatments (7.5 and 10 g l-1) and cinnamon essential oil (750 and 1000 ppm) inhibited the spread of fungal infection better than other treatments, and therefore reduced the growth of green mold. Also, different concentrations of (ja) and (chi) increased the activity of SOD and APX enzymes, while different concentrations of (epiBR) and (cin) stimulated the activity of POD and CAT enzymes. Finally, the present study proposes using natural products as an appropriate alternative to fungicides in order to reduce the citrus green mold rot

Antifungal and antimycotoxigenic activity of hydrolyzed goat whey on Penicillium spp: An application as biopreservation agent in pita bread

Whey is a by-product of the cheese industry, yet it contains proteins that have a high nutritional value and are an important source of antifungal peptides. Food deterioration caused by toxigenic fungi is one of the challenges of food safety. In this context, trypsin was used to hydrolyse goat milk whey at 37. The resultant peptides were characterised by LC–ESI–TOF-MS. Antifungal activity of the goat milk whey hydrolysate (HGW) was determined against 10 toxigenic fungi from the genus Penicillium, in solid and liquid media. Furthermore, HGW was used as an ingredient for bread elaboration. Bread elaborated with HGW and inoculated with toxigenic fungi was included in a shelf-life study of the reduction of fungal growth, mycotoxin production and the use of the additive calcium propionate in bread. A total of 27 peptides from α-lactalbumin, β-lactoglobulin, κ-casein and lactoferrin were identified. HGW evidenced fungal growth inhibition and presented minimum inhibitory concentration and minimum fungicidal concentration ranges of 3.9–62.5 and 15.8–250 g HGW/L, respectively. Bread with HGW displayed a 1-log reduction of fungal growth, 85–100% mycotoxin production, and extended the shelf-life by 2 days.

Antifungal activity and shelf life extension of loaf bread produced with sourdough fermented by Lactobacillus strains

The objective of this study was to evaluate a water-soluble extract from sourdoughs fermented with the lactic acid bacteria (LAB) for antifungal reflect on loaf bread. The extracts produced by Lactobacillus plantarum CECT 749 and L. bulgaricus CECT 4005 were effective against strains of Fusarium spp., Penicillium spp., and Aspergillus spp., with minimum inhibitory concentration ranging from 1.6 to 200 mg/ml and minimum fungicidal concentration from 1.6 to 400 mg/ml. LC-ESI-MS-TOF was used to analyze the antimicrobial compounds. Several antimicrobial phenolic acids were found. Fermented sourdoughs used for the production of loaf bread produced a reduction of fungal growth in relation on the sourdough control and improved to the shelf life of 1 to 2 days compared to control bread with 0.2% calcium propionate. Therefore, LAB are an alternative to synthetic compounds for decreasing fungal contaminants and prolonging the shelf life of food. Practical applications This study presents the importance of sourdough fermented by Lactobacillus plantarum spp. and the production during the fermentation of bioactive metabolites with antifungal activity. When applied in the preparation of bread, it is able to increase the useful life of the bread and its efficiency can be compared to that of calcium propionate. It is thus an alternative to synthetic compounds for decreasing fungal contaminants and prolonging the shelf life of food.

Combination of low concentrations of fluazinam and antagonistic rhizobacteria to control avocado white root rot

Avocado white root rot is a disease caused by the soil-borne pathogenic ascomycete Rosellinia necatrix Prill. In this work, we have carried out different experiments combining the contact fungicide fluazinam with biocontrol rhizobacterial strains of Pseudomonas chlororaphis and Bacillus subtilis, in order to reduce in vitro growth inhibition of R. necatrix and to control the disease in avocado plants. When combining fluazinam at a low concentration (0.01 mg L−1) with individual biocontrol bacterial strains, a slight reduction in fungal growth was observed (10 mm2 for PCL1606; 19 mm2 for PCL1601 and 11 mm2 for PCL1608) when compared with the use of the fungicide alone (31 mm2). From all the assayed rhizobacteria, the combined use of the rhizobacterial strain Pseudomonas chlororaphis PCL1606 with fluazinam showed the best fungal inhibition in in vitro tests (22–66%). The protective effect against avocado root rot in avocado plants was recorded using a concentration of fluazinam of 0.01%, but its effect was not improved when combined this fungicide with the biocontrol rhizobacteria PCL1606. However, when a lower concentration of fluazinam was tested (0.001%), the combination with PCL1601 or PCL1606 strains resulted in improved control of the disease than when using the fungicide alone with a reduction of 15% and 8% respectively. These results point to the development of an integrated tool to control avocado white root rot by using lower concentrations of fungicide, combined with a suitable biocontrol rhizobacteria, thus obtaining the protective effect on the plant, but reducing the chemical residues and preventing the development of fungal resistance.

Computational identification and antifungal bioassay reveals phytosterols as potential inhibitor of Alternaria arborescens

Alternaria arborescens is a major pathogen for crops like tomato, tangerine and so on and its control is mostly dependent on the application of chemical agents. Plants as the sources of natural products are very attractive option for developing eco-friendly and natural antifungal agents. In this study, we modeled three-dimensional structure of chorismate synthase (CS) enzyme from A. arborescens. Docking studies of phytosterols, namely, γ-sitosterol and β-sitosterol, with CS showed them to be potential inhibitor of CS. To explore the stability and conformational flexibility of all the AaCS complex systems, molecular dynamics simulations were performed. None of the putative inhibitors as well as β- and γ-sitosterol showed interaction with the FMNH2 binding pocket of the tomato CS (major host of A. arborescens) indicating their suitability as antifungal compounds inhibiting the shikimate pathway without causing any harm to the host. An in vivo antifungal bioassay showed a significant reduction in fungal growth in the presence of β-sitosterol (500 ppm) which resulted in ∼23% and ∼17% reduction in fungal fresh and dry weight, respectively, at 8 days after inoculation. This study provides experimental evidence establishing natural sterols like β-sitosterol can be useful in curbing A. arborescens damage in an eco-friendly manner.Communicated by Ramaswamy H. Sarma

FUSARIUM SOLANI INFECTION OF RED SWAMP CRAYFISH (PROCAMBARUS CLARKII)

In river Nile and its branches, numerous individuals of red swamp crayfish, Procambarus clarkii, displayed melanised areas in gills. To clarify the cause of these lesions, several isolates of Fusarium spp. were recovered. The fungi were first identified morphologically on culture media. Subsequently, molecular identification was carried out based on the internal transcribed spacer (ITS) region and beta-tubulin gene (TUB2) sequences. Based on GenBank database searches, the causative agent was identified as Fusarium solani. To fulfill Koch`s postulates, an experimental infection was induced using a representative isolate (ESHA-1). The challenged crayfish showed similar lesions noticed on naturally-infected ones, and the pathogen was re-isolated from the lesions of the infected individuals. Zinc oxide nanoparticles (ZnO NPs) exhibited a significant reduction in fungal growth. To our knowledge, this is the first record of Fusarium solani infection in red swamp crayfish inhabiting the River Nile.

Antifungal activities of combined treatments of irradiation and essential oils (EOs) encapsulated chitosan nanocomposite films in in vitro and in situ conditions

Cellulose nanocrystals (CNCs) reinforced chitosan based antifungal films were prepared by encapsulating essential oils (EOs) nanoemulsion. Vapor phase assays of the chitosan-based nanocomposite films loaded with thyme-oregano, thyme-tea tree and thyme-peppermint EO mixtures showed significant antifungal activity against Aspergillus niger, Aspergillus flavus, Aspergillus parasiticus, and Penicillium chrysogenum, reducing their growth by 51–77%. Combining the bioactive chitosan films loaded with thyme and oregano EOs produced ~2 log reduction in fungal growth in inoculated rice during 8 weeks of storage at 28 °C. The bioactive films showed a slow release (26%) of volatile components over 12 weeks of storage. Sensorial evaluation of rice samples packed with the bioactive films showed no significant change in odor, taste, color and general appreciation compared with untreated rice. Incorporation of cellulose nanocrystals (CNCs) with the chitosan matrix played an important role in stabilizing the physicochemical and release properties of the nanocomposite films. In addition, combining the bioactive chitosan films with a dose of 750 Gy of ionizing radiation showed significantly higher antifungal and mechanical properties than treatment with the bioactive film or irradiation alone.

Maize resistance to ear rot caused by Aspergillus parasiticus

The fungus Aspergillus parasiticus produces aflatoxins, the most important group of mycotoxins considering their potential toxicity that may cause cancer in humans. Prevention is the most important and economically most beneficial practice in the reduction of fungal growth and mycotoxin production. Due to that, the development of resistant maize genotypes is the most effective method. The aim of the present study was to analyse the resistance of maize hybrids to pathogenic and toxigenic A. parasiticus isolates originating from maize in Serbia. Hybrids used belong to three FAO maturity groups and showed a high level of resistance to A. parasiticus species. A combination of prevention management strategies and good grain management at harvest can lessen the impact of Aspergillus ear rot on yield and grain quality.

Antifungal activity of combined treatments of active methylcellulose-based films containing encapsulated nanoemulsion of essential oils and γ–irradiation: in vitro and in situ evaluations

Microfluidization was used to develop methyl cellulose (MC)/cellulose nanocrystal CNC based nanocomposite films containing a plant essential oil (EO) blend (oregano: thyme) emulsion. A three factorial experimental design was used to systematically optimize the microfluidization pressure based on size and antifungal activity of the prepared emulsion. Results showed that microfluidization of the film forming dispersions provide a novel approach for the development of high strength bionanocomposite films. Incorporation of 7.5% CNC into MC containing 0.50–0.75% EO and application of a pressure of 15 k psi (103 MPa) created a nanoemulsion with particle size ≤ 100 nm which exhibited significant antifungal activity in vitro against Aspergillus niger, A. flavus, A. parasiticus and P. chrysogenum. In situ tests with MC/CNC based bioactive films containing EO emulsion produced a 2 log reduction in fungal growth in infected rice during 8 weeks of storage at 28 °C. Methyl cellulose nanocomposite films containing EOs nanoemulsion showed a slow release (35%) of volatile component over 12 weeks of storage period. The addition of CNC as reinforcing filler improved the tensile strength of the MC based films by 30% and decreased water barrier and release properties by 9 and 25% respectively. In addition, combined treatment of bioactive films with an irradiation treatment at 750 Gy showed more pronounced antifungal and mechanical properties than treatment with the bioactive film or irradiation alone. These results show the potential for EO-loaded methyl cellulose-based films to prolong shelf life of food products.

Hydrolysis of untreated lignocellulosic feedstock is independent of S-lignin composition in newly classified anaerobic fungal isolate, Piromyces sp. UH3-1

BackgroundPlant biomass is an abundant but underused feedstock for bioenergy production due to its complex and variable composition, which resists breakdown into fermentable sugars. These feedstocks, however, are routinely degraded by many uncommercialized microbes such as anaerobic gut fungi. These gut fungi express a broad range of carbohydrate active enzymes and are native to the digestive tracts of ruminants and hindgut fermenters. In this study, we examine gut fungal performance on these substrates as a function of composition, and the ability of this isolate to degrade inhibitory high syringyl lignin-containing forestry residues.ResultsWe isolated a novel fungal specimen from a donkey in Independence, Indiana, United States. Phylogenetic analysis of the Internal Transcribed Spacer 1 sequence classified the isolate as a member of the genus Piromyces within the phylum Neocallimastigomycota (Piromyces sp. UH3-1, strain UH3-1). The isolate penetrates the substrate with an extensive rhizomycelial network and secretes many cellulose-binding enzymes, which are active on various components of lignocellulose. These activities enable the fungus to hydrolyze at least 58% of the glucan and 28% of the available xylan in untreated corn stover within 168 h and support growth on crude agricultural residues, food waste, and energy crops. Importantly, UH3-1 hydrolyzes high syringyl lignin-containing poplar that is inhibitory to many fungi with efficiencies equal to that of low syringyl lignin-containing poplar with no reduction in fungal growth. This behavior is correlated with slight remodeling of the fungal secretome whose composition adapts with substrate to express an enzyme cocktail optimized to degrade the available biomass.ConclusionsPiromyces sp. UH3-1, a newly isolated anaerobic gut fungus, grows on diverse untreated substrates through production of a broad range of carbohydrate active enzymes that are robust to variations in substrate composition. Additionally, UH3-1 and potentially other anaerobic fungi are resistant to inhibitory lignin composition possibly due to changes in enzyme secretion with substrate. Thus, anaerobic fungi are an attractive platform for the production of enzymes that efficiently use mixed feedstocks of variable composition for second generation biofuels. More importantly, our work suggests that the study of anaerobic fungi may reveal naturally evolved strategies to circumvent common hydrolytic inhibitors that hinder biomass usage.