Phosphate solubilization and synergism between P-solubilizing and arbuscular mycorrhizal fungi

The objective of this work was to evaluate the ability of several P-solubilizing fungi to solubilize aluminum phosphate and Araxá apatite as well as the synergism between the P-solubilizing fungus, PSF 7, and arbuscular mycorrhizal fungi to promote clover growth amended with aluminum phosphate. Two experiments were carried out, the first under laboratory conditions and the second in a controlled environmental chamber. In the first experiment, PSF 7, PSF 9, PSF 21 and PSF 22 isolates plus control were incubated in liquid medium at 28ºC for eight days. On the 2nd, 4th and 8th day of incubation, pH and soluble P were determined. In the second experiment, clover was sowed in plastic pots containing 300 g of sterilized substrate amended with aluminum phosphate, 3 g L-1, in presence and absence of PSF 7 isolate and arbuscular mycorrhizal fungi. A completely randomized design, in factorial outline 2x2 (presence and absence of PSF 7 and arbuscular mycorrhizal fungi) and five replicates were used. In the first experiment, higher P content was detected in the medium containing aluminum phosphate. PSF 7 is the best fungi isolate which increases aluminum solubilization with major tolerance to Al3+. Clover growth was stimulated by presence of PSF 7 and arbuscular mycorrhizal fungi. There is synergism between microorganisms utilized to improve plant nutrition.

Necrotrophic fungi associated with epidermal microcracking caused by chilling injury in pickling cucumber fruit

The objective of this work was to visualize the association between microcracking and other epidermal chilling injury symptoms, and to identify rots in cucumber fruit (Cucumis sativus L.) by scanning electron microscopy (SEM). Depressed epidermal areas and surface cracking due to damages of subepidermal cells characterized the onset of pitting in cucumber fruit. The germination of conidia of Alternaria alternata, with some of them evident on the fractures in the cultivar Trópico, occurred after damaging on the epidermis. Before, the chilling injury symptoms became visible, Stemphylium herbarum conidia germinated, and mycelium penetrated through the hypodermis using the microcracks as pathway. In the cultivar Perichán 121 the fungus was identified as Botrytis cinerea.

New isolates of ectomycorrhizal fungi and the growth of eucalypt

The objective of this work was to evaluate the efficiency of ectomycorrhizal isolates on root colonization, phosphorus uptake and growth of Eucalyptus dunnii seedlings. Inocula of ten ectomycorrhizal isolates of Chondrogaster angustisporus, Hysterangium gardneri, Pisolithus spp., and Scleroderma spp. were aseptically produced in a peat-vermiculite mixture supplemented with liquid culture medium. Plants grew in a similar substrate supplemented with macro-and micro-nutrients; treatments were randomly distributed in a greenhouse. After three months, seedlings inoculated with three isolates - UFSC-Sc68 (Scleroderma sp.), UFSC-Ch163 (Chondrogaster angustisporus), and UFSC-Pt188 (Pisolithus microcarpus) - had a phosphorus shoot content and a shoot dry matter higher or equivalent to those of noninoculated controls which had been fertilized with a 16-fold phosphorus amount. These isolates were selected for new studies for establishing inoculum production techniques, in order to be applied in reforestation programmes under nursery and field conditions.

Acclimatization of Tapeinochilos ananassae plantlets in association with arbuscular mycorrhizal fungi

The objective of this work was to assess the potential of three isolates of arbuscular mycorrhizal fungi to promote growth of micropropagated plantlets of Tapeinochilos ananassae during acclimatization. The experiment was carried out in greenhouse, in a completely randomized block design, with four inoculation treatments: non‑inoculated control and plants inoculated with Glomus etunicatum, Acaulospora longula or Gigaspora albida, with ten replicates. After 90 days, the following parameters were evaluated: survival rate, height, leaf and tiller number, leaf area, fresh and dry biomass, contents of macro‑ and micronutrients in the root and shoot, glomerospore number, and mycorrhizal colonization. The survival percentage was 100%, except for plants inoculated with G. albida (80%). The isolate G. etunicatum is more suitable for plant development, since it improves survival, growth, dry matter production, nutritional status, and vigor of T. ananassae micropropagated plants.

Arbuscular mycorrhizal fungi in soil aggregates from fields of "murundus" converted to agriculture

The objective of this work was to evaluate the spore density and diversity of arbuscular mycorrhizal fungi (AMF) in soil aggregates from fields of "murundus" (large mounds of soil) in areas converted and not converted to agriculture. The experiment was conducted in a completely randomized design with five replicates, in a 5x3 factorial arrangement: five areas and three aggregate classes (macro-, meso-, and microaggregates). The evaluated variables were: spore density and diversity of AMF, total glomalin, total organic carbon (TOC), total extraradical mycelium (TEM), and geometric mean diameter (GMD) of soil aggregates. A total of 21 AMF species was identified. Spore density varied from 29 to 606 spores per 50 mL of soil and was higher in microaggregates and in the area with 6 years of conversion to agriculture. Total glomalin was higher between murundus in all studied aggregate classes. The area with 6 years showed lower concentration of TOC in macroaggregates (8.6 g kg-1) and in microaggregates (10.1 g kg-1). TEM was greater at the top of the murundus in all aggregate classes. GMD increased with the conversion time to agriculture. The density and diversity of arbuscular mycorrhizal spores change with the conversion of fields of murundus into agriculture.

Novas tendências para o tratamento de resíduos industriais contendo espécies organocloradas

The toxic character of organochloride compounds, their habitual presence in many industrial effluents, and mainly the low efficiency of the current remediation processes, are important aspects that have been promoted to study new degrading technologies. Among the great number of new physical and chemical alternatives, the photochemical and electrochemical processes have been played an important role, mainly due to their high degradation capacity through relatively low-cost procedures. In these contexts biological processes, the use of white-rot fungi, or even ligninolytic enzymes produced from them, are also very promising alternatives. However, the necessity of long reaction time and the high cost of the enzyme production process are some of the drawbacks that difficult the definitive consolidation of these processes.

Biodegradação de efluente têxtil por Pleurotus sajor-caju

Effluents generated by the textile industry are of environmental concern because of the presence of dyes with complex molecular structure, which confer them recalcitrant characteristics. Indigo is one of the most widely used dyes within the textile sector and studies have suggested that edible fungi may be capable of its biodegradation. A textile effluent was mixed with sugarcane bagasse and inoculated with Pleurotus sajor-caju, the decolorization being evaluated after 14 days, when the process was observed. Enzymatic activities of laccase, peroxidase and manganese peroxidase were determined, the production of these ligninolytic enzymes being evident and a synergism among them being likely in the decolorizing process.

Antifungal activity against postharvest fungi by extracts from Colombian propolis

The aims of the present study were to evaluate the antifungal properties of Colombian propolis extracts against Colletotrichum gloeosporioides and Botryodiplodia theobromae, and to isolate and identify the main constituents from the active extracts. Therefore, propolis samples were thoroughly extracted with n-hexane/methanol (EPEM), dichloromethane, ethyl acetate, and methanol. Experimental results indicated that mycelial growth of all selected microorganisms was reduced in culture media containing EPEM and dichloromethane fractions. Furthermore, through antifungal bioassay-guided fractionation, three known labdane-type diterpenes: isocupressic acid (1), (+)-agathadiol (2) and epi-13-torulosol (3) were isolated as the main constituents from the active fractions.

Enantioselective biotransformation of propranolol to the active metabolite 4-hydroxypropranolol by endophytic fungi

The enantioselective biotransformation of propranolol (Prop) by the endophytic fungi Phomopsis sp., Glomerella cingulata, Penicillium crustosum, Chaetomium globosum and Aspergillus fumigatus was investigated by studying the kinetics of the aromatic hydroxylation reaction with the formation of 4-hydroxypropranolol (4-OH-Prop). Both Prop enantiomers were consumed by the fungi in the biotransformation process, but the 4-hydroxylation reaction yielded preferentially (-)-(S)-4-OH-Prop. The quantity of metabolites biosynthesized varied slightly among the evaluated endophytic fungi. These results show that all investigated endophytic fungi could be used as biosynthetic tools in biotransformation processes to obtain the enantiomers of 4-OH-Prop.

Metabolic response induced by endophytic fungi and bacteria in H. marrubioides Epling in vitro microplants

Hyptis marrubioides Epling is a native plant from Brazilian Cerrado. In this paper, the response of in vitro microplants of this species to inoculation with bacterial and fungal endophytic isolates is evaluated. HPLC-DAD analysis showed the presence of 3,4-O-(Z)-dicaffeoylquinic acid and quercetin-7-O-glucoside as the main components. GC/MS analysis demonstrated that the sesquiterpenes τ-cadinol and caryophyllene oxide were only produced in microplants inoculated with endophytic bacteria, while methyl hexadecanoate, methyl heptadecanoate and methyl (Z,Z,Z) 9,12,15-octadecatrienoate and the triterpene methyl 3β-hydroxy-urs-12-en-28-oate were overexpressed only when the microplant was treated with endophytic fungi.

ASYMMETRIC SULFOXIDATION OF ALBENDAZOLE TO RICOBENDAZOLE BY FUNGI: EFFECT OF pH

Albendazole (ABZ) is an anthelmintic drug used for the treatment of infectious diseases in veterinary and human medicine. This drug is a prochiral drug that after administration, is rapidly oxidized in the pharmacologically active sulfoxide metabolite, which is also known as ricobendazole (ABZSOX). ABZSOX has a stereogenic center and possibly two enantiomers, (+)-ABZSOX and (-)-ABZSOX. In the present work, we investigate the pH effect on the asymmetric stereoselective sulfoxidation of ABZ into ABZSOX by employing the fungi Nigrospora sphaerica, Papulaspora immera Hotson, and Mucor rouxii. The results show a possibility of obtaining the pure enantiomers of the ricobendazole drug using fungi as biocatalytic agents. The three fungi showed a high degree of enantioselectivity expressed by enantiomeric excess. In addition, M. rouxii can be used as an alternative to obtain the (+)-ABZSOX enantiomer (ee 89.8%).

Detection, transmission, pathogenicity and chemical treatment of fungi in Ceiba speciosa seeds

The aim of this work was to evaluate fungus association, transmission and pathogenicity, besides chemical seed treatment in Ceiba speciosa seeds from different regions of southern Brazil. Seven seed samples were used to do the germination test, fungus detection by blotter test and potato-dextrose-agar (PDA), fungus transmission and pathogenicity tests; besides, chemical seed treatments were tested. Germination ranged from 0 to 59,5%. The following fungi were associated in the seeds: Fusarium sp., Alternaria sp., Colletotrichum sp., Curvularia sp. and Pestalotia sp.; in addition, Fusarium sp. was found in all the samples. Alternaria sp. and Fusarium sp. were transmitted by seeds. The isolates of Alternaria sp., Colletotrichum sp. and Fusarium sp., were pathogenic to seedlings and seeds. The seed treatment with methyl tiophanate and the combination captan + methyl tiophanate reduced Fusarium sp. incidence.

Biocontrol of Sclerotinia sclerotiorum and white mold of soybean using saprobic fungi from semi-arid areas of Northeastern Brazil

ABSTRACTThe incidence and the levels of yield loss caused by the white mold of soybean (caused by the fungus Sclerotinia sclerotiorum) have increased in areas of higher altitude at Cerrado and Southern Brazil, causing yield losses of up to 60%. The aim of this study was to select saprobic fungi with the potential to control the white mold of soybean. First, in vitroantagonism screening was carried out to test eight saprobic fungi against S. sclerotiorum. Assessment of S. sclerotiorum mycelial growth was done at four and seven days after its placement on the culture medium. The isolate showing greatest antagonistic effect in all tests/assessments was Myrothecium sp. An in vivo experiment was conducted in a greenhouse and growth chamber, where plants previously treated with eight saprobic fungi were artificially inoculated with S. sclerotiorum. The fungal culture medium (potato-dextrose) and the commercial resistance inducer acibenzolar-S-methyl were used as controls. In the in vivotests, severity of the white mold was assessed at 8, 14 and 21 days after inoculation. The highest reduction percentage in the lesion length was observed for the treatment with Myrothecium sp. (70%), which has the greater potential to be used as biocontrol agent of soybean under the conditions of this experiment.

Fungi associated to bark lesions of Eucalyptus globulus stems in plantations from Uruguay

Trees with stem bark lesions are frequently observed in Eucalyptus globulus Labill. plantations, particularly in the central west region of Uruguay. These lesions constitute a problem for trunk decortications at harvest and they also facilitate the access of fungi that could cause wood decay. Seven, three and oneyear-old plantations, located at three sites in close proximity were selected. Four types of trunk lesions were present in trees regardless the age of plantation and more than one type was found in each plantation. The aim of this study was to investigate the fungal composition associated with these lesions and compare them to healthy tissues and try to find out the origin of these symptoms. Another purpose was to elucidate the real role of the fungi considered pathogens by means of experimental inoculations. Segments from lesions and healthy tissues yielded 897 fungal isolates belonging to 32 taxa, 681 isolates from bark lesions and 216 from healthy tissues. Both healthy and symptomatic tissues showed similar fungal species composition, but with differences in frequencies of colonization. Cytospora eucalypticola Van der Westhuizen, Botryosphaeria spp., Pestalotiopsis guepinii (Desm.) Stey. and Penicillium spp. were the dominant species isolated. As symptoms were not reproduced after experimental inoculation with Botryosphaeria ribis Grossenb. & Duggar and B. eucalyptorum Crous, & M.J. Wingf, it could be suggested that these lesions were originated by unfavorable environmental conditions. The frost that occurred for several days out of season and flooding may have been involved in the development of bark lesion.

The role of arbuscular mycorrhizal fungi on the early-stage restoration of seasonally dry tropical forest in Chamela, Mexico

It was evaluated the effect of two different sources of local inocula from two contrasting sites (mature forest, pasture) of arbuscular mycorrhizae fungi (AMF) and a non-mycorrhizal control on the plant growth of six woody species differing in functional characteristics (slow-, intermediate- and fast-growth), when introduced in a seasonally tropical dry forest (STDF) converted into abandoned pasture. Six plots (12 X 12m) were set as AMF inoculum source. Six replicates of six different species arranged in a Latin Square design were set in each plot. Plant height, cover area and the number of leaves produced by individual plant was measured monthly during the first growing season in each treatment. Species differed in their ability to benefit from AMF and the largest responsiveness in plant height and leaf production was exhibited by the slow-growing species Swietenia humilis, Hintonia latiflora and Cordia alliodora. At the end of the growing season (November), the plant height of the fast growing species Tabebuia donnel-smithii, Ceiba pentandra and Guazuma ulmifolia were not influenced by AMF. However, inocula of AMF increased leaf production of all plant species regardless the functional characteristics of the species, suggesting a better exploitation of above-ground space and generating a light limited environment under the canopy, which contributed to pasture suppression. Inoculation of seedlings planted in abandoned pasture areas is recommended for ecological restoration due to the high responsiveness of seedling growth in most of species. Use of forest inoculum with its higher diversity of AMF could accelerate the ecological restoration of the above and below-ground comunities.