Native Fungal Strains Research Articles

Adhesion and virulence properties of native Metarhizium fungal strains from Burkina Faso for the control of malaria vectors

BackgroundLocal strains of the entomopathogenic fungus Metarhizium pingshaense in Burkina Faso have demonstrated remarkable virulence against malaria vectors, positioning them as promising candidates for inclusion in the future arsenal of malaria control strategies. However, the underlying mechanisms responsible for this virulence remain unknown. To comprehend the fungal infection process, it is crucial to investigate the attachment mechanisms of fungal spores to the mosquito cuticle and explore the relationship between virulence and attachment kinetics. This study aims to assess the adhesion and virulence properties of native Metarhizium fungal strains from Burkina Faso for controlling malaria vectors.MethodsFungal strains were isolated from 201 insects and 1399 rhizosphere samples, and four strains of Metarhizium fungi were selected. Fungal suspensions were used to infect 3-day-old female Anopheles coluzzii mosquitoes at three different concentrations (106, 107, 108 conidia/ml). The survival of the mosquitoes was measured over 14 days, and fungal growth was quantified after 1 and 24 h to assess adhesion of the fungal strains onto the mosquito cuticle.ResultsAll four fungi strains increased mosquito mortality compared to control (Chi-square test, χ2 = 286.55, df = 4, P < 0.001). Adhesion of the fungal strains was observed on the mosquito cuticle after 24 h at high concentrations (1 × 108 conidia/ml), with one strain, having the highest virulent, showing adhesion after just 1 h.ConclusionThe native strains of Metarhizium spp. fungi found in Burkina Faso have the potential to be effective biocontrol agents against malaria vectors, with some strains showing high levels of both virulence and adhesion to the mosquito cuticle.Graphical

Bioremediation of Triphenylmethane and Sulfonated Azo Dyes Using an Indigenous Strain of Trichoderma Asperellum: Mechanisms and Efficacy Assessment

This study aimed to isolate a native fungal strain that was potent enough to curb the toxicity of azo dyes in textile effluent drain sludge. The native fungus, which has the potential to degrade several azo dyes under ‘non-sterile’ conditions, was isolated and identified as Trichoderma asperellum (TA). It was observed that the isolated strain was capable of decolorizing up to 71.42 %, 60.19 %, and 89.65 % of azo dyes (methyl orange, malachite green, and crystal violet, respectively) within a span of 14 days with an extensive range of temperatures (15°C-40°C) and pH (5-8) before optimization. The targeted dyes at concentrations of 100 mg/L, 200 mg/L, 300 mg/L, 400 mg/L, and 500 mg/L were decolorized after optimization. The maximum decolorization of methyl orange (MO), malachite green (MG), and crystal violet (CV) was 88.89 %, 71.09 %, and 92.75 %, respectively, at a dye concentration of 100 mg/L, pH of 6.5, and temperature of 25°C. The fungal isolate Trichoderma asperellum frequently contains chitinases, cellulose, and laccases. The findings of this study validated the potential of TA as an effective biocatalyst for the remediation of methyl orange, malachite green, and crystal violet in textile wastewater. The degradation products showed decreased toxicity to sprout seeds, such as Cicer arietinum (chickpea) and Vigna radiata (mung seeds), when compared to untreated wastewater.

From purposeless residues to biocomposites: A hyphae made connection

Biocomposites create attractive alternatives to match packing needs with available agricultural residues. Growing native fungal strains developed a mycelium biocomposite over a mixture of Peach Palm Fruit Peel Flour and Sugar Cane Bagasse Wet Dust. A methodology was proposed to analyze their main characteristics: 1) morphological, 2) chemical, and 3) biodegradability. 1) SEM analysis evidenced the structural change of the dried vs pressed material and mycelium morphology for both species. 2) The ratio lignin:carbohydrate showed that P. ostreatus degrades the cellulose-hemicellulose fraction of the substrate at a higher rate than T. elegans, and 3) the curve BMP indicated that these materials are readily biodegradable with a maximum yield of 362,50 mL biogas/g VS. An innovative tangible valorization strategy based on mass balances is also presented: from just 50 kg of peel flour, up to 1840 units can be manufactured, which could pave the way for a more sustainable future.

Inoculation with Oidiodendron maius BP Improves Nitrogen Absorption from Fertilizer and Growth of Vaccinium corymbosum during the Early Nursery Stage.

Blueberry roots are inefficient in taking up water and nutrients, a fact partially related to their scarcity of root hairs, but they improve nutrient uptake by associating with ericoid mycorrhizal and endophytic fungi. However, the benefits of this association are both cultivar- and fungus-dependent. Our objective was to assess the effect of inoculation with three native fungal strains (Oidiodendron maius A, O. maius BP, and Acanthomyces lecanii BC) on plantlet growth, plantlet survival, and nitrogen (N) absorption of the southern highbush blueberry (SHB) cultivars Biloxi and Misty. The fungal strains were inoculated into the peat-based substrate for growing blueberry cultivars, and plantlets produced by micropropagation were transplanted and grown for four months. The three inoculated strains positively affected the survival percentage in at least one of the cultivars tested, whereas O. maius BP positively affected plant biomass, N derived from fertilizer absorption, N content, and plant N recovery (%) in both Biloxi and Misty. Our results show that the O. maius BP strain may prove useful as a bio-inoculant to improve blueberry production during the nursery stage.

Comparative evaluation of chemical and bio techniques for uranium leaching from low grade sandstone rock sample, Abu Thor, southwestern Sinai, Egypt

Ferruginous sandstone considered as a one of the economically significant uranium mineralized areas in the southwestern part of the Sinai that located at the lower member of Um Bogma Formation in Abu Thor area. The studied sample was characterized geologically as a sandstone rock contain 450 mg/kg of uranium. This work is aimed to compare between eco-friendly bioleaching and conventional leaching processe. The uranium bioleaching efficiency achieved 80% by using a native fungal strain; Aspergillus nidulans as a green technology with the optimimum conditions as; 3 pH value, 3% pulp density, 7 days incubation period, and 30 °C incubation temperatures. Whereas the traditional technique using alkaline and sulphuric acid leaching attained 68.5% and 95% respectively at the best condition. Finally, the shrinking core model was represented the layer diffusion process by acquiring apparent activation energy 18.28 and 16.82 kJ/mol for carbonate and sulphuric acid leaching, respectively.

Field Efficacy of Metarhizium rileyi Applications Against Spodoptera frugiperda (Lepidoptera: Noctuidae) in Maize.

The efficacy of the fungus Metarhizium rileyi (Farlow) Kepler, S. A. Rehner & Humber (Hypocreales: Clavicipitaceae) against the fall armyworm Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) and the impact on the community of epigeans predators as well as the natural occurrence of native fungal strains were evaluated after sequential sprays in maize. In the first season, the infestation was lower than 0.2 larvae per plant throughout the three fungal sprays and no significant difference was observed in the number of infected larvae among treatments. In the second season, insect population reached an average of 0.8 larvae per plant between the second and third sprays and the number of larvae succumbed by M. rileyi was higher in fungal-treated plots in the following weeks. Molecular characterization of the collected isolates on mummified larvae revealed the introduction of a new isolate did not eliminate the native strain on the fungal-treated plots. In both seasons, the diversity and abundance of predator species in the plots were not affected by any of the treatments. We showed that applications of selected strains of M. rileyi early in the season have no significant impact on the occurrence of natural enemies in maize.

Isolation, characterization, culturing, and formulation of a new Beauveria bassiana fungus against Diaphorina citri

The Asian citrus psyllid, Diaphorina citri, is a worldwide destructive citrus pest. It aids in the transmission of a group of phloem-limited bacteria (Candidatus Liberibacter spp.) that leads to Huanglongbing (HLB) disease. In this study, a new Chinese native fungal strain (F-HY006) was isolated from the cadavers of D. citri collected from Ganzhou, Jiangxi in China (114°94′ E, 25°87′ N). The isolate was virulent towards adult female D. citri with corrected mortality of 76% and LT50 of 4.09 d after application of a suspension containing 107 conidia/ml (400 µl/citrus seedling). Morphologic and phylogenetic analyses identified this isolate as Beauveria bassiana. Based on its virulence against D. citri and growth characteristics (2.89 ± 0.28 × 105 conidia/cm2) on the PDA plate, biphasic (liquid–solid) cultivation for conidia production of B. bassiana F-HY006 was optimized using several nutritional and environmental factors. Soybean meal + cottonseed powder (1:1) and continuous fluorescent light resulted in the highest conidial production (5.7 × 109/g dry substrate). Moreover, the oil-based conidial formulation was optimized using sesame oil as an effective carrier, which resulted in a significant enhancement of the conidial shelf life, tolerance to thermal stress, and virulence against D. citri compared to unformulated conidia. Therefore, we have prepared a potential mycopesticide for the biological control of D. citri based on the optimized biphasic culture growth and formulation of an isolated virulent fungus, B. bassiana F-HY006.

Screening and metabolic potential of fungal strains isolated from contaminated soil and sediment in the polychlorinated biphenyl degradation

Polychlorinated biphenyls (PCBs) are widespread persistent pollutants deleterious for environment and very dangerous for human kind. As the bioremediation of PCB polluted sites by model white-rot fungi is still unsatisfactory, the use of efficient native strains which have the natural capacity to develop on polluted sites may constitute a relevant alternative strategy. In this study, we isolated 12 fungal strains from PCB contaminated soil and sediment, improved the screening method to obtain the most efficient ones in biodegradation and detoxification of PCBs and characterized potential underlying enzymatic activities. Four strains Penicillium chrysogenum, P. citreosulfuratum, P. canescens and Aspergillus jensenii, showed remarkable biodegradation capacities, greater than 70%. The remaining PCB-toxicity of their culture, including that of Trametes versicolor and Acremonium sclerotigenum, which present interesting ecological and metabolic properties, was studied. Only P. canescens was able to significantly reduce the toxicity related to PCBs and their metabolites. The enzymatic activities induced by PCBs were different according to the strains, namely laccases in T. versicolor and peroxidases in Ac. sclerotigenum. Our promising results show that the use of native fungal strains can constitute an effective strategy in the depollution of PCB polluted sites.

Soil Type Affects Organic Acid Production and Phosphorus Solubilization Efficiency Mediated by Several Native Fungal Strains from Mexico.

Phosphorus (P) is considered a scarce macronutrient for plants in most tropical soils. The application of rock phosphate (RP) has been used to fertilize crops, but the amount of P released is not always at a necessary level for the plant. An alternative to this problem is the use of Phosphorus Solubilizing Microorganisms (PSM) to release P from chemically unavailable forms. This study compared the P sorption capacity of soils (the ability to retain P, making it unavailable for the plant) and the profile of organic acids (OA) produced by fungal isolates and the in vitro solubilization efficiency of RP. Trichoderma and Aspergillus strains were assessed in media with or without RP and different soils (Andisol, Alfisol, Vertisol). The type and amount of OA and the amount of soluble P were quantified, and according to our data, under the conditions tested, significant differences were observed in the OA profiles and the amount of soluble P present in the different soils. The efficiency to solubilize RP lies in the release of OAs with low acidity constants independent of the concentration at which they are released. It is proposed that the main mechanism of RP dissolution is the production of OAs.

Trichoderma atroviride as a promising biocontrol agent in seed coating for reducing Fusarium damping-off on maize.

The objective of this work was to identify a fungal strain showing potential biocontrol abilities against two Fusarium damping-off agents and to test it as a Biological Control Agent (BCA) in maize seed coating under field conditions. A collection of native fungal strains associated with maize in Belgium was screened for antagonistic potential against Fusarium avenaceum and Fusarium culmorum. The strain with highest biocontrol potential was identified as an endophytic Trichoderma atroviride BC0584. In greenhouse, it significantly improves the emergence of seedlings infected by F. avenaceum or F. culmorum pathogens. In most field trials carried out during the season 2017, it significantly increased the emergence rate of infected seedlings compared to untreated seeds. One slurriable powder formulation allows BCA conidia to survive over a 6-month storage period at 4°C. The fungal BC0584 strain is a promising BCA that could be an alternative to synthetic fungicides. It is adapted to local environmental conditions, is easily and cheaply produced and can be stored in a low-cost formulation. In Belgium, this is the first study to use a T. atroviride native strain against Fusarium damping-off on maize crop. Modes of action and required conditions for ensuring high biocontrol activity in the field have still to be investigated.

Occurrence of Nematophagous Fungi in Freshwater Samples of Toba Lake, North Sumatra, Indonesia

Root-knot nematodes are important agricultural pests causing serious economical loss to harvestable crops. Biological control using nematophagous fungi is one option to mitigate these infection through mechanism of physical or chemical killing methods. The present study tried to explore a possibility of finding native nematophagous fungal strains in the hope on discovery of novel and potential isolates originating from freshwater region of Toba Lake, North Sumatra, Indonesia. Isolation of nematophagous fungi was based on sprinkle and pour combination method on Chloramphenicol-Water Agar (CWA) incubated for 30 days. Freshwater samples of soil and sediments were collected from 28 sampling sites characterized by different anthropogenic activities as natural, fishery, residential, plantation and tourism area. Daily examination is conducted to obtain a single culture of nematophagous fungi sub-cultured on Potato Dextrose Agar (PDA) medium. Eleven isolates were observed to initiate predatory activities against tested Caenorhabditis elegans based on qualitative screening. The isolates showed either mechanical killing or chemical killing of nematodes during co-inoculation with nematodes. Micromorphological and molecular analysis are currently being conducted to obtain species identity from each isolate.

Optimization and Characterization of Extracellular Cellulase Produced by Native Egyptian Fungal Strain

Since accumulation of agricultural wastes represents a huge problem, it was important to explore the available methods to help eliminate agricultural wastes safely, and simultaneously produce functional enzyme like cellulase. Six native Egyptian fungal strains were isolated, morphologically identified and screened for cellulose biodegradation potential, which was determined as endoglucanase or as carboximethylcellulase (CMCase). The most promising isolate (Aspergillus terreus) was selected for molecular characterizations based on sequencing of internal transcribed spacer (ITS). Further optimization experiments were accomplished on the selected strain. The strain with cellulolytic activity, 2.26 IU mL-1 was identified using ITS nucleotides (genes) sequences and the result confirmed that the strain is 99.8% homology with A. terreus. Then, it was submitted to GeneBank and given an accession number. Further optimization experiments revealed that 35ºC is the optimum temperature for cellulase production and raised the enzyme activity (EA) up to 3.19 IU mL-1. Out of two organic nitrogen sources; peptone at concentration 6 gL-1 was found to be the optimum nitrogen source for cellulase production with the highest activity 4 IU mL-1. Whereas, the different four carbon sources: microcellulose, corn stalks, wheat straw and rice straw showed significant differences in EA with values 11.07, 9.68, 7.87 and 3.71 IU mL-1, respectively at pH 3. The maximum EA was recorded to be within 5-7 days of incubation, dependent on type of carbon sources. The optimization of different incubation conditions raised cellulolytic activity from 2.26 IU mL-1 up to 11.18 IU mL-1.&#x0D; &#x0D; *********&#x0D; In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 3, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue.&#x0D; *********

Effects of Native Entomopathogenic Fungal Strains and Neem Extract on Spodoptera frugiperda on Maize

The objective of this study was to evaluate the insecticidal activity of native entomopathogenic fungi and neem extract on Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) attacking maize (Zea mays L.). The treatments were the following: Metarhizium robertsii J.F. Bisch., Rehner & Humber and Fusarium solani (Mart.) Sacc at 1 × 108 spores ml-1 and 15% vegetable oil, neem extract in two combinations of 4% mass per volume, commercial insecticide, and a control without application. Response variables were incidence of S. frugiperda, severity of leaf damage, and grain yield. M. robertsii was most effective because of low incidence of S. frugiperda and severity of leaf damage; as leaf damage increased, grain yield decreased. Therefore, a high severity by insect attack can significantly decrease grain yield. It was observed that during the autumn-winter cycle the S. frugiperda incidence was lower, compared to the spring-summer cycle. M. robertsii decreased S. frugiperda incidence in both cycles.

Bioremediation of cardboard recycling industrial wastewater using isolated native fungal strains

Bioremediation of cardboard recycling industrial wastewater using isolated native fungal strains

Extraction and spray drying of Class II hydrophobin HFBI produced by Trichoderma reesei

Abstract Hydrophobins are considered the strongest surface-active proteins from microbial origin. The amphiphilic proteins are produced by filamentous fungi and exhibit unique physicochemical properties. Self-assembly into membranes at hydrophobic-hydrophilic interfaces illustrate their unique properties, leading to a broad range of applications, from foam stabilization to protein immobilization. Due to insufficient production quantities of Class II hydrophobins using native fungal strains and limited long-term storage stability of liquid formulations, commercial availability remains lacking. Within this research, the potential of trehalose for stabilization and preservation of hydrophobins during spray drying was studied. Therefore, the Class II hydrophobin HFBI, expressed by Trichoderma reesei, was produced by submerged cultures in fed-batch mode and extracted from the mycelium. Extracts purified with FPLC were subsequently spray dried. Residual activity of 93.62 ± 5.07% was obtained with trehalose in a ratio of 2:1 (excipient:protein) to stabilize HFBI during spay drying, which demonstrates the huge potential of trehalose.

Biodecolourization and biodetoxification of dye-containing wastewaters from leather dyeing by the native fungal strain Trametes villosa SCS-10

The native fungal strain Trametes villosa SCS-10 was investigated for its ability to treat wastewaters from real dyeing of leather produced in pilot-scale. Four types of wastewater using different compositions and dyes (Acid Red 357 and Acid Orange 142) were produced and used in the assays. Three culture conditions were studied. The efficiency of the treatment was assessed in terms of biodecolourization, mycoremediation: reduction of chemical oxygen demand (COD), biological oxygen demand (BOD), total organic carbon (TOC) and biodetoxification. The treatment resulted in between 50–70% of biodecolourization and 40–60% of COD and TOC reduction of the raw wastewater without nutrient addition (N0). However, when wastewaters were supplemented with a high (N1) and a reduced (N0.5) nutrient supply, over 90% of biodecolourization and over 80% of COD and TOC reduction were achieved. The treatment N0.5 allowed the highest values of colour, TOC and COD reduction, which were related to the major peaks of laccase activity (1000–1300 UL−1). The ecotoxicity assays with Raphidocelis subcapitata and Vibrio fisheri demonstrated that the fungal treatment resulted in 50–70% of biodetoxification. The MTT assay revealed that the treated wastewaters did not present cytotoxic effects to the cell line V79. These promising results show that Trametes villosa is suitable for the treatment of wastewater from leather dyeing. Further studies are required to improve the applicability of selected fungal strains in the treatment of wastewater from the tannery industry.

Effects of native arbuscular mycorrhizal and phosphate-solubilizing fungi on coffee plants

The effects of the interaction between arbuscular mycorrhizal and phosphate-solubilizing (P-solubilizing) fungi on phosphorous availability, acid phosphatase activity, and the growth and development of coffee plants (Coffea arabica L.) var. garnica were evaluated. The experiment was performed under controlled conditions and was based on a randomized factorial design with two factors. Coffee plants were inoculated with a consortium of arbuscular mycorrhizal fungi (CAMF), two strains of P-solubilizing fungi (PSF) (Aspergillus niger [An] and Penicillium brevicompactum [Pb]), the possible combinations of the latter fungi, and an uninoculated control. After 8 months, the results demonstrated the effectiveness of mycorrhizal and P-solubilizing fungal inoculations in increasing available soil phosphorous. The greatest concentration of available soil phosphorous was detected in the consortium of P-solubilizing fungi (CPSF) treatment at 3.8 mg/kg. The total foliar phosphorous concentration of plants was higher in the CAMF, An + CAMF, CPSF + CAMF, Pb + CAMF, and CPSF treatments in comparison to the control treatment. The growth of coffee plants was also favored by the consortium treatments (P-solubilizing fungi and arbuscular mycorrhizal fungi). The acid phosphatase activity in the rhizosphere significantly increased under the CPSF treatment and also increased in the roots of coffee plants under the An, An + CAMF, and CPSF + CAMF treatments. Given the importance of fungal groups for processes of phosphorous transformation and absorption in coffee plants, it is imperative to continue the search for native fungal strains with high potential for use as biofertilizers.

Schizophyllan production by newly isolated fungus Schizophyllum commune IBRC-M 30213: optimization of culture medium using response surface methodology

Schizophyllan (SPG) is a commercially attractive biopolymer produced by Schizophyllum commune. An investigation on the potential for SPG production by Iranian native S. commune was conducted based on culture medium, fermentation conditions and bioreactor type, . Nine native fungal strains were isolated from the northern forest of Iran at different times. Based on growth rate and SPG production, one strain was selected for further study. Optimal medium composition and inoculum size for maximizing SPG production and minimizing biomass were determined using central composite design by setting sucrose, yeast extract, inoculum size, carboxymethyl cellulose and oleic acid in the ranges of 50–200 g/L, 1–4 g/L, 2–10%, 2–12 g/L and 0.032–0.222%, respectively. The results showed that optimal results were obtained at 93.47 g/L sucrose, 1.87 g/L yeast extract, 7.68% inoculum size, 9.07 g/L carboxymethyl cellulose and 0.13% oleic acid, with maximum SPG production of 9.97 g/L and minimum biomass of 35.18 g/L. Under these optimal conditions, the production of SPG was studied in stirred tank and bubble column bioreactors. The results revealed greater production in the stirred tank because of better mixing of the culture medium. The SPG produced was characterized using rheometery, Fourier transform infrared spectroscopy, nuclear magnetic resonance), scanning electron microscopy and gel permeation chromatography. The results of these characterizations demonstrated the similarity of the SPG produced by S. commune IBRC-M 30213 to commercial SPG. Thus, the SPG produced shows good potential as a polysaccharide for use in various industries.

Enzymatic Potential of Native Fungal Strains of Agave Residues

Twelve strains of fungi from residues of Agave durangensis were isolated and identified by molecular techniques for evaluation of their hydrolytic enzyme production capability. A proportion (50%) of the fungal strains belonged to the Aspergillus genus and the other strains used belonged to Alternaria, Neurospora crassa, Mucor sp, Rhizopus sp., Botryosphaeria sp., and Scytalidium sp. The isolated strains were evaluated for their potential to produce extracellular enzymes using different substrates (cellulose, xylan, inulin, Agave fructans, starch, and tannic acid). It was observed that most of the tested strains were capable of simultaneously secreting cellulases, xylanases, inulinases, fructanases, and laccases. Botryosphaeria sp. ITD-G6 was selected for its evaluation in the production of inulinase, using different substrates. Showing high inulinase activities (5.22 U / mL for Agave waste, 4.37 U/ mL for inulin and 5.00 U / mL for Agave fructans).

Expression of a novel recombinant cyanate hydratase (rTl-Cyn) in Pichia pastoris, characteristics and applicability in the detoxification of cyanate

A recombinant Pichia pastoris harbouring the cyanate hydratase gene (rTl-Cyn) from the thermophilic fungus Thermomyces lanuginosus SSBP yielded a high titre of extracellular cyanate hydratase (100±13UmL−1) which was ∼10-fold higher than the native fungal strain. The purified rTl-Cyn had a molecular mass of ∼20kDa on SDS-PAGE, with Km, Vmax, kcat and kcat/Km values of 0.34mM, 2857.14µmolesmg−1min−1, 2.14×104s−1 and 6.3 ×107M−1s−1, respectively. Its properties of thermostability, pH stability, and heavy metals insensitivity, make it a suitable candidate for bioremediation in extreme environments. The rTl-Cyn was able to degrade toxic cyanate completely with the liberation of ammonia, which was confirmed by FTIR analysis. This is the first report of any known cyanate hydratase that has been expressed in P. pastoris, characterized and effectively evaluated for cyanate detoxification.