Avaliação química e microbiológica do capim-elefante, cultivar taiwan A-148, preparado para ensilagem com bagaço de cana-de-açúcar

Elephant grass (Pennisetum purpureum Schum.), was cut after nine weeks of regrowth and mixed with 10, 20, 30 and 40% of sugar cane bagasse (SCB) with the objective of reducing the moisture content of the ensiled mass. Willing of the grass for eight and twelve hours was used as a comparative treatment. Initial dry matter of the grass (13%) increased in the forage mass to 17, 23, 24 and 27% by the addition of 10, 20, 30 and 40% of the SCB respectively. Wilting for eight and twelve hours increased initial dry matter to 18 and 24% respectively. Buffering capacity of elephant grass was reduced by the addition of 40% of SCB. Clostridium spores in the ensiled mass tended to be lower due to the effect of the two pre-treatments. Initial dry matter and number of spores of Clostridium were negatively correlated although without statistic significance. The addition of SCB reduced (P < 0.0.5) soluble carbohydrates and crude protein percentages in the ensiled mass. It was concluded that wilting is more effective than the addition of SCB in the practice of ensiling elephant grass.

Evaluation of survival of Staphylococcus aureus and Clostridium botulinum in charqui meats

Charqui meats were prepared in laboratory conditions in order to carry out experiments to observe the possibility of development of enterotoxigenic Staphylococcus aureus and Clostridium bottilinum proteolytic type B spores and their toxins. Results demonstrated that the harsh processing conditions, high salt concentration, relative high temperature, a, values, inhibited the growth of both bacteria. Under our experimental conditions, S. aureus would survive throughout the sequence of salting steps i.e. brine followed by rock salting and the sunshine drying step. However, at final a(w) value of 0.70-0.75 would create conditions to inhibit its development. The other experiment revealed that C. botulinum spores germination also was impaired because of these low a(w) values. Under these conditions, charqui meats revealed to be safe products in relation to toxins from both enterotoxigenic S. aureus and C. botulinum. (C) 2003 Elsevier B.V. Ltd. All rights reserved.

Infecção experimental pelo Encephalitozoon cuniculi em camundongos imunossuprimidos com dexametasona

Objective Microsporidian Encephalitozoon cuniculi has been recognized as an opportunistic pathogen in immunosuppressed individuals, such as AIDS patients. The objective of the study was to develop pharmacologically immunosuppressed animals as a model of the natural occurring E. cuniculi infection.Methods Distint groups of adult Balb-C mice were immunosuppressed with different doses of dexamethasone (Dx, 3 or 5 mg/kg/day, intraperitoneal route - IP) and inoculated with E. cuniculi spores by IP route intraperitoneally. Control groups (inoculated animals but non-immunosuppressed and non-inoculated animals but immunosuppressed) were also used. The spores of E. cuniculi were previously cultivated in MDCK cells. The animals were sacrificed and necropsied at 7, 14, 21, 28 and 35 days post-inoculation. Tissue fragments were collected and processed for light microscopy studies, using Gram-chromotrope and hematoxylin-eosin staining techniques.Results In all immunosupressed and inoculated inoculated immunosuppressed mice,specially in those that received 5 mg/kg/day of dexamethasone, the most prominent necropsy findings were hepatomegaly and splenomegaly. The experimental inoculation resulted in a disseminated non-lethal infection, characterized by granulomatous lesions in several organs (liver lungs, kidneys, gut and brain) but notably in the hepatic tissue. Spores of E. cuniculi were only seen in few animals treated with 5 mg/kg/day of Dx at 35 days post-infection.Conclusions Microsporidiosis in Dx-immunosuppressed mice provides a useful model for studies of the microsporidial infection, resembling that one naturally occurring in immunodeficient individuals with AIDS.

Stimulation of polygalacturonase production in an immobilized system by Aspergillus sp.: effect of pectin and glucose

The synthesis of polygalacturonases (PG) is known to be influenced by Aspergillus growth conditions, namely, environmental factors and pectin content in the cultivation medium containing a mixed carbon source. Optimal conditions were attained at a temperature of 30 A degrees C and an initial pH of 4.5. PG activity (3.29 and 2.48 U/mL) was determined after a two-day culture of Aspergillus sp. HC1 and Aspergillus sp. CC1, respectively, in a basic medium containing 2% citrus pectin as the sole carbon source. The addition of glucose (2% w/v) to the basic medium led to a 2-fold increase in PG production. However, enzyme synthesis was repressed when a higher concentration of glucose was used in the medium containing the mixed carbon source. Spores from the two fungi were immobilized in a 3% Ca-alginate system and the mechanical strength of the gel beads allowed the use of this process system 6-fold longer (288 h) than the free culture. In the Aspergillus sp. CC1 immobilized system, PG production increased nearly 10-fold in the medium with 2% glucose added (5.95 U/mL) in comparison to the medium without sugar (0.55 U/mL). The results demonstrate that a different response in activity was produced by free and entrapped spore systems. PG production remained approximately constant throughout the six 48 h cycles in the medium containing citrus pectin (2% w/v) as the sole carbon source.

Associação micorízica em espécies arbóreas, atividade microbiana e fertilidade do solo em áreas degradadas de cerrado

The recuperation of areas used during the construction of the hydroelectric plant, especially in 'borrowed areas', is a difficult and long process since all vegetation and the fertile layer of soil were removed. Interventions in these degraded areas could accelerate the revegetation process. The objective of this research was to evaluate the association of arbuscular mycorrhizal fungi (AMF) in tree species, microbial activity (basal respiration) and fertility of 'cerrado' degraded areas. Soil from two areas, pasture soil and exposed subsoil, were utilized. Organic and mineral fertilization, and liming, were added to the pit for better seedlings' initial growth, where 50 mL of preserved cerrado soil was applied as inoculum of microorganisms. Seedlings of 11 tree species were planted: Anadenanthera falcata (Benth.) Speg ('angico-preto'), Acacia polyphylla D. C. ('monjoleiro'), Stryphnodendron adstringens (Mart.) Coville ('barbatimao'), Dimorphandra mollis Benth ('faveiro'), Hymenaea stigonocarpa Mart. ex Hayne ('jatoba-de-cerrado'), Dipteryx alata Vog. ('baru'), Machaerium acutifolium Vogel ('jacaranda-do-campo'), Schinus terebinthifolia Raddi ('aroeirapimenteira'), Magonia pubescens St. Hil. ('tingui'), Lafoensia pacari St. Hil. ('dedaleira') and Tabebuia aurea (Manso) Benth. & Hook ('ipe-amarelo'). Twelve months later, root samples were colleted at the depth of 0-0.10 m and used for evaluations. The subsoil, as compared to pasture soil, was poor in organic matter and presented less microbial activity. The highest mycorrhizal colonization was seen in the species Acacia polyphylla D. C. (monjoleiro), Magonia pubescens St. Hil. (tingui), Hymenaea stigonocarpa Mart. ex Hayne (jatoba-de-cerrado) and Schinus terebinthifolia Raddi (aroeira-pimenteira). These species could be indicated in revegetation projects in 'cerrado' degraded areas. Plants from both areas showed seedlings form high mycorrhizal colonization and low numbers of spores.

Hepatogenous photosensitization of ruminants by Brachiaria decumbens and Panicum dichotomiflorum in the absence of sporidesmin: Lithogenic saponins may be responsible

As part of a study of plants involved in crystal-associated hepatogenous photosensitization diseases, samples of Brachiaria decumbens and Panicum dichotomiflorum on which cattle and goats had recently been photosensitized were analyzed. The level of saponins associated with these photosensitization outbreaks were determined by GC-MS. Only low levels of Pithomyces chartarum spores were present on the B decumbens, and all isolates obtained failed to produce sporidesmin.

Produção de biomassa por fungos Filamentosos em meio de vinhaça de cana-de-açúcar suplementado com melaço

Three species of filamentous fungi, Aspergillus niger, Penicillium fellutanum and Mucor hiemalis, were selected and cultivated in vinasse media with different addition of molasses, pasteurized to 85°C for 30 minutes and with pH = 5.0. The microorganisms, previously adapted to the respective medium for 48 hours, from a solution of 107 spores.ml-1, were cultivated in pure and mixed cultures in Erlenmeyer vessel of 500ml, to 30°C, with constant agitation of 170 rpm, for 24, 48 and 72 hours, with four repetition for each samples. The biomass was separated by vacuum filtration in filter Whatman #1 and dried in oven at 105°C until right weight, the obtained liquid was submited to COD analysis. The datas were statistically analysed using a response surface methodology, to improve the effect on the molasses proportion and culture time, in the biomass production by microorganism in research. According to the obtained results (5.02% of molasses, 55.59h, 70% of spores solution of A. niger and 30% of spores solution of P. fellutanum), cultivating was carried out in Microferm Fermentor New Brunswick for 48 hours at 300 rpm, aired at 1v/v/m, using 5 liters of medium added with 5.0% of molasses on the conditions above described. The average of the results obtained (6.81g.l-1) was higher than the confidence interval (5.937 ; 6.369) and was inside the prediction interval (4.471 ; 7.834) both of them significant at 95% by the statistical test employed.

Fermentacao de 26-deoxilaidlomicina por Streptomyces sp. Ar386

In a previous work a strain of microorganism was isolated in Araraquara region, SP, Brazil, and characterized as being Streptomyces sp. Ar386, producer of 26-deoxylaidlomycin and of more three polietheric antibiotics. In this paper there are presented studies about fermentation characteristics of the antibiotic performed in incubator agitator utilizing various cultivation technics and media. A medium containing part of energy source as free sugar and part as amilaceous material presented the best result. As the Streptomyces sp. Ar386 produced few spores, it was necessary special care to provide sufficient quantity of microorganisms in inoculation. The biosynthesis of antibiotics intensified between the forth and seventh day. The yields varied from 8 to 443 mg of antibiotic complex per litre of medium. As a polyether antibiotic it may be used as anticoccidal agent in poultry and as growth promoters in cattle and swine.

Antibiotic 26-deoxylaidlomycin isolated from Streptomyces sp. Ar386 from Brazilian soil

An actinomycete strain (Ar386) was isolated from the soil of the Araraquara regio, SP, Brazil. The strain, named Streptomyces jacareensis, formed irregular rayed, rugose, grayish-white mycelium with sinuous, branched hyphae carrying rare isolated spores; assimilated glucose, galactose, inositol, ribose, maltose, sucrose, melibiose and starch but not mannitol, rhamnose, arabinose, xylose, lactose and raffinose; and contained LL- diaminopimelic acid in its cell wall. An antibiotic active against Gram- positive bacteria, which was characterized as being 26-deoxylaidlomycin and which may have application against poultry coccidiosis, was isolated from cultures of the strain. This was the first isolation of this antibiotic from a microorganism of the genus Streptomyces and also the first isolation of this antibiotic in Brazil.

The deep mycoses in HIV infection

The deep mycoses are uncommon infections, usually acquired from the inhalation or ingestion of fungal spores, sometimes from the soil in areas of endemicity, such as in the Americas and south-east Asia, or from decaying vegetable matter. They are also seen in immunocompromised persons and, increasingly, in HIV-infected persons. Respiratory involvement is frequent, with granuloma formation, and mucocutaneous involvement may be seen. Oral lesions of the deep mycoses are typically chronic but non-specific, though nodular or ulcerative appearances are common. Person-to-person transmission is rare. In HIV disease, the most common orofacial involvement of deep mycoses has been in histoplasmosis, cryptococcosis, aspergillosis and zygomycosis. Diagnosis is usually confirmed by lesional biopsy although culture may also be valuable. Treatment is with amphotericin or an azole.

Efeito de biofertilizantes sobre o crescimento micelial e a germinação de esporos de alguns fungos fitopatogênicos

The biofertilizer was produced through anaerobic fermentation of cow manure adding milk, sugar, salts, cow liver parts and bone powder. After 73 days of fermentation it was evaluated the effect on micelial growth of Pythium aphanidermatum, Alternaria solani, Stemphylium solani, Septoria licopersici, Sclerotinia sclerotiorum, Botrytis cinerea, Rhizoctonia solani, Fusarium oxysporum f. sp. phaseoli and spores germination of B. cinerea, A. solani, Hemileia vastatrix and Coleosporium plumierae. In relation to micelial growth inhibition, the growth rate was calculated and it was found that, in general, concentrations over 10% caused a total inhibition of growth for the majority of fungi assayed. In case of spores germination, biofertilizer concentration over 20% has inhibited completely the germination of B. cinerea, over 10% inhibited A. solani, 5 and 1% of C. plumierae and H. vastatrix, respectively. Three different biofertilizers were also tested and one of them was less effective, which was the one produced with manure from confined cows opposed to the others produced with grazing cows.

Effect of Alternaria cassiae, Pseudocercospora nigricans, and soybean (Glycine max) planting density on the biological control of sicklepod (Senna obtusifolia)

The interactions of two fungal biocontrol agents, Alternaria cassiae and Pseudocercospora nigricans, and soybean planting density on sicklepod mortality and dry weight were studied in the field over 2 yr. The experimental field was divided into three equal areas: one without soybean and two where the soybean was sown in densities of 20 and 36 seeds per meter row with a 0.95-m row spacing. The fungi were sprayed alone or in a mixture at three growth stages of sicklepod plants grown at three levels of crop interference resulting from the three soybean planting densities. The fungal treatments were: an untreated control, A. cassiae (105 spores/m2), P. nigricans (3.3 g mycelium/m2), and the mixture of these two fungi. Sicklepod was at the cotyledonary leaf, two-leaf, and four-leaf stages when treated. Alternaria cassiae was most effective in reducing both sicklepod survival and dry weight. The mixture of P. nigricans and A. cassiae was generally comparable to but not better than A. cassiae alone in killing the weed (mortality) and reducing its growth (dry weight). Soybean density did not have significant effects on the mortality or the dry weight of sicklepod. Thus, there is no advantage to combining the highly effective biocontrol agent A. cassiae with the less effective P. nigricans or with soybean interference to control sicklepod. However, the results validate the efficacy of A. cassiae by itself as a bioherbicide.

Bacillus thuringiensis development from 1971 to 1996: Cases of a research group in Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Thermal inactivation of Phytophthora nicotianae

Phytophthora nicotianae was added to pasteurized soil at the rate of 500 laboratory-produced chlamydospores per gram of soil and exposed to temperatures ranging from 35 to 53°C for 20 days. The time required to reduce soil populations to residual levels (0.2 propagule per gram of soil or less) decreased with increasing temperatures. Addition of cabbage residue to the soil reduced the time required to inactivate chlamydo spores. Temperature regimes were established to simulate daily temperature changes observed in the field, with a high temperature of 47°C for 3 h/day, and were good estimators of the efficacy of soil solarization for the control of P. nicotianae in soil. Cabbage amendment reduced the time required to inactivate chlamydospores of P. nicotianae and its effect was more pronounced at lower temperature regimes.

Survival and conjugation of Bacillus thuringiensis in a soil microcosm

The survival and conjugation ability of sporogenic and asporogenic Bacillus thuringiensis strains were investigated in broth, in non-amended sterile clay soil monoculture and in mixed soil culture. The 75 kb pHT73 plasmid carrying an erythromycin resistance determinant and a cry1Ac gene was transferred in mating broth and soil microcosm. Survival of strains was assessed in soil monoculture and in mixed soil culture for up to 20 days. Sporogenic strains rapidly formed viable spores which were maintained until the end of the experiment. The asporogenic strains were no longer recovered after 8 days of incubation. This study shows that the environmental impact of asporogenic B. thuringiensis strains is lower than that of sporogenic B. thuringiensis strains. Thus, the use of asporogenic strains may significantly reduce any potential risk (gene transfer, soil and plant contamination) due to the dissemination of B. thuringiensis-based biopesticides in the environment. Copyright (C) 2000 Federation of European Microbiological Societies.