Bionectria Ochroleuca Research Articles

Antifungal Activity of Mycogenic Silver Nanoparticles on Clinical Yeasts and Phytopathogens.

In this study, seven different silver nanoparticles (AgNPs) were obtained using the fungi species from the phylum Ascomycota, Aspergillus tubingensis, Aspergillus spp., Cladosporium pini-ponderosae, Fusarium proliferatum, Epicoccum nigrum, Exserohilum rostratum, and Bionectria ochroleuca, isolated from the Brazilian biodiversity, particularly from the mangrove and Caatinga biomes. The nanoparticles were coded as AgNP-AT, AgNP-Asp, AgNP-CPP, AgNP-FP, AgNP-EN, AgNP-ER, and AgNP-BO and characterized using spectrophotometry (UV-Vis), dynamic light scattering (DLS), zeta potential, transmission electron microcopy (TEM), and Fourier-transform infrared (FTIR) spectroscopy. All the AgNPs presented homogeneous size in the range from 43.4 to 120.6 nm (DLS) and from 21.8 to 35.8 nm (TEM), pH from 4.5 to 7.5, negative charge, and presence of protein coating on their surface. The antifungal activity of the AgNPs was evaluated on clinical strains of Candida albicans, and on the non-albicans species, Candida krusei, Candida glabrata, Candida parapsilosis, Candida tropicalis, and Candida guilliermondii, common in hospital infections, and against the phytopathogens Fusarium oxysporum, Fusarium phaseoli, Fusarium sacchari, Fusarium subglutinans, Fusarium verticillioides, and Curvularia lunata, which are species responsible for serious damage to agriculture production. The AgNPs were effective against the yeasts with MICs ranging from 1.25 to 40 µM and on the phytopathogens with MICs from 4 to 250 µM, indicating the promising possibility of application of these AgNPs as antifungal agents. The results indicated that the physicochemical parameters of the AgNPs, including the functional groups present on their surface, interfered with their antifungal activity. Overall, the results indicate that there is no specificity of the AgNPs for the yeasts or for the phytopathogens, which can be an advantage, increasing the possibility of application in different areas.

Asexual reproduction and vegetative growth of Bionectria ochroleuca in response to temperature and photoperiod.

Growth and reproduction are two essential life‐history traits for fungi. Understanding life‐history strategies provides insight into the environmental adaption of species. Here, we investigated the colonial morphology, vegetative growth, and asexual reproduction of the ascomycete fungus Bionectria ochroleuca in response to a variety of environmental conditions. We demonstrated that the increased temperature from 15 to 25°C induced mycelial growth and conidiation in B. ochroleuca. We also found that the optimal temperatures for mycelial growth and conidial formation in this fungus species were 25 and 30°C, respectively. However, as the temperature increased from 25 to 30°C, mycelial growth was suppressed, but the total number of conidia was significantly increased. The shift in light–dark cycles dramatically changed the morphological features of the colonies and affected both vegetative growth and asexual reproduction. Under incubation environments of alternating light and dark (16:8 and 8:16 light:dark cycles), conidiophores and conidia in the colonies formed dense‐sparse rings and displayed synchronous wave structures. When the light duration was prolonged in the sequence of 0, 8, 16, and 24 hr per day, mycelial growth was suppressed, but conidiation was promoted. Together, our results indicate that temperature and light period may trigger a trade‐off between vegetative growth and asexual reproduction in B. ochroleuca.

Bioremediation Performance of Two Telluric Saprotrophic Fungi, Penicillium Brasilianum and Fusarium Solani, in Aged Dioxin-contaminated Soil Microcosms

ABSTRACT In this study, 28 strains of filamentous fungi were isolated from soil that were historically contaminated with polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs; northern France). These fungal isolates were selected for their ability to use hexadecane as the sole carbon source and for hydrophobic molecule behavior. Six strains produced significant dry biomass (> 25 mg) on hexadecane: Paecilomyces carneus, Penicillium brasilianum, Absidia glauca, Lecanicillium lecanii, Mortierella minutissima, and Bionectria ochroleuca. In a second experiment, P. brasilianum and F. solani were tested for their ability to dissipate 17 PCDD/F congeners in non-sterile contaminated soil microcosms using olive oil as an unconventional carbon source. After two months of incubation, P. brasilianum significantly reduced the soils’ toxicity equivalency (TEQ) by 35%. The F. solani treatment led to a significant reduction (approximately 25%) in PCDD/F concentrations. Statistical agglomerative hierarchical clustering analysis indicated that using cardboard as a growing medium and bulking agent is more efficient than using poplar wood. As fungal dioxin dissipation can involve the production of reactive oxygen species or fungal P450-like enzymes, the potential role of these mechanisms deserve further study. However, the proposed approach could allow the development of cost-effective and eco-friendly (low technology) techniques to maintain the integrity of soils.

Pathogenic analyses of fungus strains isolated from medicinal Fritillaria przewalskii Maxim. bulb rot

AbstractBulb rot causes a great loss of rare perennial medicinal Fritillaria przewalskii Maxim., which is exacerbated with growth year and seriously constrains the plant productivity, but the pathogens responsible for the disease were still unknown. In this paper, we attempted to explore the potential pathogens leading to bulb rotting and their occurrence patterns in artificial domesticated F. przewalskii. Fungus strains were isolated from the bulb rot spot of the 3‐ to 5‐year‐old diseased F. przewalskii plants by tissue separation, further assayed for pathogenicity according to Koch's law and finally identified by both morphological and molecular methods. Seven pathogenic strains (F1‐F7) were detected in 5‐year‐old rot bulbs, six (F1‐F6) in 4‐year‐old rot bulbs and four (F1, F2, F5, F6) in 3‐year‐old rot bulbs. All of the strains were able to infect bulbs by stabbing and some exhibited varying levels of aggressiveness. Relative to the non‐stabbing controls, the bulbs stab‐inoculated with F5, F2, F7, F4, F1, F6, and F3 showed 76.65%, 75.15%, 71.44%, 40.37%, 39.09%, 36.87%, and 34.93% rot after 8 days, respectively. Phylogenetic analysis revealed that these seven strains were clustered into Bionectria ochroleuca (F1, F3, F4), Fusarium oxysporum (F2, F7), Fusarium tricinctum (F5), and Clonostachys rosea (F6). The two species of Fusarium had the strongest pathogenicity, followed by Bionectria ochroleuca and Clonostachys rosea. Although leading to low bulb rot incidence by stab inoculation, F1 showed the highest isolation rate (48.9%) among all strains. Thus, the edible and medicinal bulbs of F. przewalskii are susceptible to synergetic contamination by these seven pathogens at some point after their third year of growth, which has contributed to the species endangered status, with the two strains of Fusarium being the predominant pathogens. To our knowledge, this is the first report on the seven strains of four fungal species causing F. przewalskii bulb rot in China.

Effect of Acetyl-CoA Carboxylase (ACC) on Lipid Production in Endophytic Fungi from Torreya grandis

Certain endophytic fungi isolated from Torreya grandis can produce similar unsaturated lipid of high economic value as its host plants. However, the lipid yield produced by endophytic fungi is very low. Acetyl-CoA carboxylase (ACC) is one of the key enzymes responsible for fatty acid synthesis. In this study, the impact of ACC on lipid yield of endophytic fungi were analyzed and the inhibitory effect of endophytic fungus metabolites on the ACC activity were investigated. Our results showed thatthe ACC activity was found to be positively correlated with the lipid content of endophytic fungi and the kernels of Torreya grandis. The ACC activity was inhibited by the metabolite, benzoic acid 2,2,6,6-tetramethyl-4-piperidinylester, which was extracted from the endophytic fungus Bionectria ochroleuca XF-38. Furthermore, the gene sequence of CT subunit of ACC in Bionectria ochroleuca XF-38 were cloned and successfully expressed in E. coli BL21 (DE3), and we revealed that the CT subunit of ACC is the target of benzoic acid 2,2,6,6-tetramethyl- 4-piperidinylester.

Functional textiles impregnated with biogenic silver nanoparticles from Bionectria ochroleuca and its antimicrobial activity.

Biogenic silver nanoparticles (AgNPs) were obtained throughout the fungal biosynthesis using extracellular filtrate of the epiphytic fungus B. ochroleuca and were incorporated in cotton and polyester fabrics by common impregnation procedure that was repeated once, twice or four times. Both fabrics were analyzed by scanning electron microscopy (SEM), and the effectiveness of impregnation was determined using inductively coupled plasma optical emission spectrometry (ICP OES). The AgNPs loaded fabrics showed potent antimicrobial activity on Staphylococcus aureus and Escherichia coli as well as on clinically relevant Candida albicans, Candida glabrata, and Candida parapsilosis, indicating that the AgNPs impregnation of cotton and polyester fabrics was efficient. AgNPs effectively inhibited the biofilm formation by Pseudomonas aeruginosa and was not toxic to Galleria mellonella larvae indicating a promising probability of biotechnological application.

Fungi isolated from shoots showing ash dieback in the Wolica Nature Reserve in Poland and artificially inoculated seedlings with Hymenoscyphus fraxineus

Abstract Ash dieback caused by an alien, invasive fungus Hymenoscyphus fraxineus is a serious disease of European ash species in many parts in Europe. In Poland, the disease was recorded in the beginning of the 1990s. This study was performed in 2016–2017 with the aim to identify fungi isolated from ash shoots showing dieback symptoms in the Wolica Nature Reserve in Poland, as well as from shoots of two years-old ash seedlings inoculated with H. fraxineus in the greenhouse. The most frequently isolated fungi from shoots of common ash (associated with the pathogenic fungus H. fraxineus) were identified on the basis of sequencing of the internal transcribed spacer region (ITS1) of fungal rDNA. In total, 19 fungal taxa were identified for ash shoots as follows: H. fraxineus, Fusarium avenaceum, Alternaria spp., Phomopsis oblonga, Diplodia mutila and other Phomopsis spp. The pathogen H. fraxineus was not found for all the shoots samples; one year after inoculation the aforementioned fungi and other species as: Alternaria alternata, Bionectria ochroleuca, Epicoccum nigrum, F. acuminatum, F. avenaceum, and Paraphaesphaeria neglecta were identified in inoculation point, as well as H. fraxineus. The same quantitative and qualitative changes of organisms were observed in the case of artificially colonised ash seedlings in the greenhouse, as well as in the shoots of adult ash trees in the forest.

Occurrence and diversity of cultivable autochthonous microscopic fungi in substrates of old environmental loads from mining activities in Slovakia

Distribution and biodiversity of soil microscopic fungi in 5 areas of old environmental loads in Slovakia were studied in relation to very low amount of organic matter (%TOC from 0.2 to 3.54) and to the pH gradient from ultra-acidic (< 3.5) to very strongly alkaline (> 9.0). All soil samples were affected by several hundred years of mining activities and contained heavy metals and other toxic elements: arsenic, cadmium, copper, zinc, antimony, lead. Concentrations of toxicants highly exceeded their limited values. Fifty-three genera and 112 species of microscopic fungi were identified. Among them, Zygomycota occurred very rarely (8 genera and 12 species), except of samples with the highest content of TOC (2.01–3.54% - samples 2 and 6), regardless their pH. Though, on the other hand, from some similar samples (3, 5 and 9), incl. those with relatively high TOC (0.14–2.62%), the lower fungi were not recovered. Forty one genera and 95 species of Ascomycota represented the most abundant fungal phylum in all investigated samples. Among them, Penicillium chrysogenum var. chrysogenum, Aspergillus niger and Neosartorya fischeri were isolated the most often. Phytopathogenic moulds of Bionectria ochroleuca, Lewia infectoria, Phoma macrostoma and Phlebia acerina were also occurred frequently. The highest biodiversity of microfungal community was recorded in the extreme acidic environment, followed by the neutral, ultra-acidic and the very strong acidic ones. There was no similarity in microfungal spectrum found in the samples studied. Except of the ultra acidic and extreme acidic samples (1−2) as well as the ultra acidic and strong acidic ones (1−4) with the most rich mycobiota, that may indicate a certain similarity degree.

Nuevos registros de Hypocreales (Sordariomycetes, Ascomycota) del bosque mesófilo de montaña de la Sierra Alta Hidalguense en México

Antecedentes y Objetivos: El orden Hypocreales se distribuye ampliamente en las regiones templadas y tropicales del mundo. Se han registrado 17 especies en el bosque mesófilo de montaña para México. El objetivo de este estudio es ampliar el conocimiento taxonómico de las especies de Hypocreales en México y en particular de la Sierra Alta Hidalguense.Métodos: Fueron realizadas cinco exploraciones en la Sierra Alta Hidalguense entre 2011 y 2014. Fueron recolectadas ocho especies y se describieron morfológicamente siguiendo las técnicas tradicionales micológicas.Resultados clave: Se citan por primera vez siete especies de Hypocreales para México. Bionectria grammicospora pertenece a la familia Bionectriaceae; Hypomyces boletiphagus a Hypocreaceae, Sarcopodium flavolanatum, Thelonectria ostrina, T. veuillotiana y Viridispora alata a Nectriaceae y Valetoniella pauciornata a Niessliaciaceae. Bionectria ochroleuca se registra por vez primera para el bosque mesófilo de montaña en el estado de Hidalgo. Se presentan descripciones taxonómicas e ilustraciones de las ocho especies.Conclusiones: Los bosques mesófilos de montaña de México son ecosistemas con alta diversidad de especies y el orden Hypocreales no es la excepción, por lo que es necesario continuar realizando exploraciones y estudios taxonómicos de este grupo de hongos en este tipo de vegetación.

Succession and Natural Occurrence of Saprobic Fungi on Leaves ofMagnolia liliiferain a Tropical Forest

Leaves of Magnolia liliifera were selected to evaluate fungal diversity, and succession of fungi during leaf decomposition, and the effect of baiting on fungal diversity. The leaf samples were from Doi Suthep-Pui National Park, Chiang Mai, Thailand. Twenty-three taxa were identified on senescent leaves of M. liliifera during the decay process. Distinct fungal communities were observed with the dominant species on the leaves being different at each succession stage. The most abundant fungal species were Hyponectria sp. 1 (on 60% of leaves), Volutella sp. 1 (60%), Gliocladium sp. 3 (37.1%), Corynespora cassiicola (34.3%), Bionectria ochroleuca (25.7%), Cylindrocladium floridanum (22.8%), Phaeosphaeria sp. (17.1%), Dactylaria longidentata (11.4%) and Lasiosphaeria sp. (11.4%). Leaf bait trials did not show any noticeable effect on fungal diversity when either the upper or lower leaf surface was adjacent to the forest floor. Highest fungal diversity on leaves of M. liliifera occurred between day 4 and 40, with most species being present on day 40. On day 56, leaves were found to be skeletonized, and the fungal communities had decreased in number.

Autochthonous Microbiota in Arsenic-Bearing Technosols from Zemianske Kostoľany (Slovakia) and Its Potential for Bioleaching and Biovolatilization of Arsenic

Studied technosols represent a unique system of a 50-year-old environmental burden after dam failure of coal-ash pond. The released ashes rich in arsenic with a thickness of 1–2 m were covered by a 40-cm thick layer of soil. Long-term exposure and selection pressure of elevated concentrations of arsenic (a range of 93–634 μg/g) induced the formation of the specific adapted autochthonous microorganisms. The phylum Proteobacteria was identified as a dominant phylum in the soils and represented only by one class—Gammaproteobacteria with six species. The species of phylum Firmicutes, Bacteroidetes and Actinobacteria were also identified. Thirty-three species of identified autochthonous microscopic fungi belong to 18 genera with the most abundant Mortierella alpina (Zygomycota). The most frequent identified mycobiota belongs to genera Penicillium, Aspergillus, Trichoderma and Alternaria. The isolates of Alternaria triticina, Bionectria ochroleuca, Chrysosporium queenslandicum, Exophiala psychrophila, Metarhizium robertsii, Trichoderma rossicum and Phlebia acerina were identified for the first time in Slovakia. Despite the stimulation of autochthonous community by nutrient medium and augmentation by native species, As leachability was relatively low—on average 5.63 wt.%, 9.23 wt.% and 17.04 wt.% of the total As for inoculated Pseudomonas chlororaphis ZK-1, Pseudomonas putida ZK-5 and Aspergillus niger, respectively. The highest As leachability was achieved through biostimulation of autochthonous microbiota using liquid SAB medium (34.73 wt.% of total As content). Additionally, microbial activity was efficient in the biovolatilization of As from soils (∼70 wt.% of the total As volatilized). It appears that bioremediation using microorganisms represents one of the possible ways of As removal from soils containing coal-combustion ashes with elevated concentrations of As.

Statistical optimization of culture medium for production of exopolysaccharide from endophytic fungus Bionectria ochroleuca and its antitumor effect in vitro.

Endophytic fungi have been recognized as possible useful sources of bioactive metabolites. However, exopolysaccharide (EPS) production from endophytic fungi and its antitumor activity have been less explored. In the present study, endophtic fungus Bionectria ochroleuca M21 was exploited for the production of EPS in submerged culture. Among tested medium components, glucose, yeast extract, MgSO4 and Tween80 were found to be effective and significant on EPS production. Response surface methodology (RSM) was employed to optimize medium composition. The results showed that the significant factors were glucose, yeast extract and Tween80. The optimal medium was observed at the composition of glucose 55.7 g/L, yeast extract 6.04 g/L, MgSO4 0.25g/L and Tween80 0.1 % (v/v). Using the optimized medium, EPS production was achieve at 2.65 ± 0.16 g/L after 4 days fermentation in a 5L bioreactor. Examination of cytotoxicity showed that the EPS from B. ochroleuca M21 did not have cytotoxic activity on human liver HL-7702 cells at concentration 0.025-1.6 mg/mL. In contrast, the EPS exhibited antiproliferative activities against cell lines of liver cancer (HepG2), gastric cancer (SGC-7901) and colon cancer (HT29) in a dose- and time-dependent manner in the concentration ranges of 0.1-0.45 mg/mL.

Isolation and fatty acid analysis of lipid-producing endophytic fungi from wild Chinese Torreya Grandis

Torreya grandis is a rare tree species of economic value. Its seeds are rich in lipids, although their use is limited by their high cost. Recent studies demonstrated that certain endophytic fungi can produce metabolites similar to those produced by the host plant. In the present study, endophytic fungal strains capable of producing lipids were isolated from wild Chinese Torreya grandis. Among these, the XF-38 strain had the highest lipid content at 17.68%. Comparative analysis of the fatty acid composition of lipids produced by endophytic fungi and Torreya seeds by GC-MS showed that the two sources shared some of the same components, including linoleic acid, oleic acid, and sciadonic acid (5c, 11c, 14c-eicosatrienoic acid). The morphology and internal transcribed spacer rDNA of the XF-38 strain were determined, and a BLAST search showed that this strain belongs to Bionectria ochroleuca. Finally, generation of a growth curve and determination of the lipid content of strain XF-38 confirmed that lipid production was related to the amount of mycelium, and the lipid content resched 3.1 g/L in the microcrystalline cellulose meduim.

The frequency of modification of Dothistroma pine needle blight severity by fungi within the native range

Foliar disease is most often understood as the product of the interaction between host and pathogen in an abiotically conducive environment. However, other microbes within the foliar microbiome may increase or decrease disease severity as either pathogen enablers or antagonists. The frequency and extent of such disease modification in nature are largely unknown, but modification is likely to occur at high frequency in the native range of a pathogen. In this study, we provided an opportunity for six fungi to modify the severity of Dothistroma needle blight in Pinus ponderosa within part of the native range of the disease near Priest River, Idaho, USA. Five fungi were common members of the P. ponderosa microbiome in the region, and one was isolated from co-occurring Pseudotsuga menziesii. Inoculum of each of the six was applied to an average of 187 newly emerging needles in the candles (new shoots) of each of ten, seven-year-old trees; control candles were treated with sterile distilled water. Disease severity per needle (i.e., lesion length/total needle length) was determined one year later following natural infection and development of Dothistroma needle blight in a total of 13,085 needles. Five of the six fungi significantly modified disease severity; the overall model (“inoculant”, “tree”, and “inoculant x tree” as predictors) explained 53% of the variation in disease severity. Penicillium goetzii was the sole antagonist and reduced disease severity by nearly 7% compared to control needles. Four of the fungi (Sydowia polyspora, Bionectria ochroleuca, Penicillium raistrickii, and a culturable species of Elytroderma) acted as pathogen enablers, increasing disease severity 4.7%, 4.2%, 3.6%, and 2.5%, respectively. Our results show that microbial modification of expression of Dothistroma needle blight in nature may be common within the native range of the pathogen. However, with more thorough sampling of the P. ponderosa microbiome, the extent of modification may go beyond the modest effects reported here for just a few members of the microbiome of the host and its forest community.

Polyketide glycosides from Bionectria ochroleuca inhibit Candida albicans biofilm formation.

One of the challenges presented by Candida infections is that many of the isolates encountered in the clinic produce biofilms, which can decrease these pathogens’ susceptibilities to standard-of-care antibiotic therapies. Inhibitors of fungal biofilm formation offer a potential solution to counteracting some of the problems associated with Candida infections. A screening campaign utilizing samples from our fungal extract library revealed that a Bionectria ochroleuca isolate cultured on Cheerios breakfast cereal produced metabolites that blocked the in vitro formation of Candida albicans biofilms. A scale-up culture of the fungus was undertaken using mycobags (also known as mushroom bags or spawn bags), which afforded four known [TMC-151s C–F (1–4)] and three new [bionectriols B–D (5–7)] polyketide glycosides. All seven metabolites exhibited potent biofilm inhibition against C. albicans SC5314, as well as exerted synergistic antifungal activities in combination with amphotericin B. In this report, we describe the structure determination of the new metabolites, as well as compare the secondary metabolome profiles of fungi grown in flasks and mycobags. These studies demonstrate that mycobags offer a useful alternative to flask-based cultures for the preparative production of fungal secondary metabolites.

Soil sickness of peanuts is attributable to modifications in soil microbes induced by peanut root exudates rather than to direct allelopathy

The quantity and quality of peanut yields are seriously compromised by consecutive monoculture in the subtropical regions of China. Root exudates, which represent a growth regulator in peanut–soil feedback processes, play a principal role in soil sickness. The growth inhibition of a species in an in vitro bioassay enriched with root exudates and allelochemicals is commonly viewed as evidence of an allelopathic interaction. However, for some of these putative examples of allelopathy, the results have not been verified in more natural settings with plants continuously growing in soil. In this study, the phenolic acids in peanut root exudates, their retention characteristics in an Udic Ferrosol, and their effects on rhizosphere soil microbial communities and peanut seedling growth were studied. Phenolic acids from peanut root exudates were quickly metabolized by soil microorganisms and did not accumulate to high levels. The peanut root exudates selectively inhibited or stimulated certain communal bacterial and fungal species, with decreases in the relative abundance of the bacterial taxa Gelria glutamica, Mitsuaria chitosanitabida, and Burkholderia soli and the fungal taxa Mortierella sp. and Geminibasidium hirsutum and increases in the relative abundance of the bacterial taxon Desulfotomaculum ruminis and the fungal taxa Fusarium oxysporum, Bionectria ochroleuca and Phoma macrostoma. The experimental application of phenolic acids to non-sterile and sterile soil revealed that the poor performance of the peanut plants was attributed to changes in the soil microbial communities promoted by phenolic acids. These results suggest that pathogenic fungal accumulation at the expense of such beneficial microorganisms as plant growth promoting rhizobacteria, mycorrhizal fungi induced by root exudates, rather than direct autotoxicity induced by root exudates, might represent the principal cause underlying the soil sickness associated with peanut plants. We hope that our study will motivate researchers to integrate the role of soil microbial communities in allelopathic research, such that their observed significance in soil sickness during continuous monocropping of fields can be further explored.

Purification of four strains of endophytic fungi from Astragalus and their optimized liquid fermentations

This study was designed to isolate endophytic fungi from A. mongholicus (growing in northeast China) to determine whether they can produce bioactive metabolites. Four strains of endophytic fungi (strains 16, 17, 23 and 75) were successfully isolated from A. mongholicus using the surface disinfection method. According to ITS-rDNA sequences analysis, strains 16 and 75 were identified as Fusarium oxysporum, and strains 17 and 23 were identified as Bionectria ochroleuca. We applied the Box-Behnken design (BBD) to optimize the liquid fermentation conditions and obtain the maximum cell dry weight (CDW) yield. Optimal parameters were obtained under the following experimental conditions: temperature of 28°C, potato dextrose agar (PDA) liquid medium of 80 mL and rotation speed of 150 rpm. The four isolated endophytic fungi did not produce astragalosides I–IV, flavonoids or polysaccharides. Isolation of additional species of endophytic fungi from A. mongholicus and determination of their capacity to produce biologically active substances are subjects in need of further research.

Bioremediation of Crude Oil by Different Fungal Genera

One of the major environmental problems today is hydrocarbon contamination resulting from the activities related to the petrochemical industry. Bioremediation is the promising technology for treatment of these contaminated sites as it is cost effective and lead to complete mineralization. This research attempts to study the potential of different fungal genera in bioremediation of hydrocarbon. Aspergillus flavus, Aspergillus versicolor, Bionectria ochroleuca, Penicillium chermisinum and Trichoderma virens was selected for the bioremediation purpose. Screening of fungi species sensitivity towards hydrocarbons was first conducted. To enhance the growth of fungi on hydrocarbon contaminated soil, suitable bulking agent was selected prior to addition into the soil. For the period of six weeks, hydrocarbon degradation trial was conducted followed by post-treatment tests. All fungal species shows high tolerance towards hydrocarbon. Sago waste (sago hampas) is the most suitable bulking agent as all fungal species capable to grow on it. Significant differences were found in the ability of Bionectria ochroleuca to degrade hydrocarbon. Bionectria ochroleuca was able to degrade more than 70 % of the C12 to C28, with 100 % degradation of C12 and C28.

Establishment of fungal entomopathogens Beauveria bassiana and Bionectria ochroleuca (Ascomycota: Hypocreales) as endophytes on artichoke Cynara scolymus

Entomopathogenic fungi (EPF) are commonly found in diverse habitats and are known to cause mycoses in many different taxa of arthropods. Various unexpected roles have been recently reported for fungal entomopathogens, including their presence as fungal endophytes, plant disease antagonists, rhizosphere colonizers and plant growth promoting fungi. In Tunisia, a wide range of indigenous EPF isolates from different species, such as Beauveria bassiana and Bionectria ochroleuca, were found to occur in the soil, and to be pathogenic against the artichoke aphid Capitophorus elaeagni (Hemiptera: Aphididae). Since endophytic fungi are recently regarded as plant-defending mutualists and their presence in internal plant tissue has been discussed as an adaptive protection against insects, we were interested on elucidating the possible endophytic behavior of B. bassiana and B. ochroleuca on artichoke, Cynara scolymus, after foliar spraying tehcnique. The leaf spray inoculation method was effective in introducing the inoculated fungi into the plant tissues and showed, then, an endophytic activity on artichoke even 10days later. According S–N–K test, there was significant differences between the two fungal treatments, B. ochroleuca (84% a) and B. bassiana (78% a), and controls (0% b). Likewise, the inoculated entomopathogenic fungi were also isolated from new leaves even though with significant differences respectively between controls (0% c), B. bassiana (56% b) and B. ochroleuca (78% a).These results reveals significant new data on the interaction of inoculated fungi with artichoke plant as ecological roles that can be exploited for the protection of plants.

Fungal pathogen accumulation at the expense of plant-beneficial fungi as a consequence of consecutive peanut monoculturing

Peanut yield and quality are seriously compromised by consecutive monoculturing in the red soil region of southern China. Soil fungi are, however, also critical to the ecological functioning of soils and plant health and were thus the study subject here. Using 454 pyrosequencing, the entire soil fungal communities of a field where peanut had been consecutively cultured for five years and another field, where peanut had been consecutively cultured for at least 20 years, and a control field with only a single peanut crop after a lay period were compared. Fungal richness, community composition, and relative taxon abundances in soil were compared among the fields and sampling times, the latter corresponding to the pod-bearing and the pod-maturing stages. Eight hundred fungal operational taxonomic units at 97% ITS sequence identity were found among 194,783 sequence reads derived from 18 separate soil samples. Members of the phylum Ascomycota strongly dominated the soil fungal communities and putative pathogens, such as Fusarium oxysporum, Leptosphaerulina australis, Phoma sp., and Bionectria ochroleuca showed higher relative abundances in the fields where peanut was consecutively monocultured, compared to the control field, at the expense of putatively plant-beneficial fungal groups, such as Trichoderma sp., a glomeromycotan fungus, and Mortierella elongata. The results suggest that the accumulations of fungal pathogen loads at the expense of plant-beneficial fungi in the soil appear likely explanations for yield declines as a consequence of consecutive peanut cultivation.