RESUMO
Nitrogen-fixing bacteria isolated from banana (Musa spp.) and pineapple (Ananas comosus (L.) Merril) were characterized by amplified 16S ribosomal DNA restriction analysis and 16S rRNA sequence analysis. Herbaspirillum seropedicae, Herbaspirillum rubrisubalbicans, Burkholderia brasilensis, and Burkholderia tropicalis were identified. Eight other types were placed in close proximity to these genera and other alpha and beta Proteobacteria.
Assuntos
Alphaproteobacteria/classificação , Betaproteobacteria/classificação , Magnoliopsida/microbiologia , Zingiberales/microbiologia , Alphaproteobacteria/genética , Alphaproteobacteria/isolamento & purificação , Alphaproteobacteria/metabolismo , Betaproteobacteria/genética , Betaproteobacteria/isolamento & purificação , Betaproteobacteria/metabolismo , DNA Ribossômico/análise , DNA Ribossômico/genética , Dados de Sequência Molecular , Fixação de Nitrogênio , Filogenia , RNA Ribossômico 16S/genética , Mapeamento por Restrição , Análise de Sequência de DNARESUMO
In a feedlot of about 1,000 head of cattle, 146 animals died within a period of a few months affected by a disease characterized by anorexia, icterus, hemoglobinuria, constipation, or diarrhea. The clinical course of the disease lasted a few days. Postmortem findings were generalized icterus and a yellow discolored liver. The kidneys were dark brown, and the urinary bladder was filled with urine of the same dark-brown color. The main histopathological findings were centrolobular coagulative necrosis, apoptosis, bilestasis, and proliferation of bile ducts in the portal space. Changes in the kidneys included nephrosis and the presence of bile and precipitates, and cylinders of albumin and of hemoglobin in the uriniferous tubules. Liver samples, collected from 3 animals on which postmortem examinations were performed, had 2,008, 2,783 and 4,906 ppm copper in their dry matter. Two samples of poultry litter fed to the cattle contained 362 and 323 ppm copper. The green forage that formed the rest of their feed only had 4.7 ppm copper. Copper poisoning was diagnosed, most probably caused by feeding litter from poultry that had been fed a ration treated with copper sulfate to avoid aspergillosis.
Assuntos
Ração Animal/efeitos adversos , Doenças dos Bovinos/induzido quimicamente , Cobre/intoxicação , Surtos de Doenças/veterinária , Esterco , Intoxicação/veterinária , Aves Domésticas , Ração Animal/análise , Animais , Brasil/epidemiologia , Bovinos , Doenças dos Bovinos/epidemiologia , Cobre/análise , Evolução Fatal , Rim/efeitos dos fármacos , Rim/patologia , Fígado/química , Fígado/efeitos dos fármacos , Fígado/patologia , Esterco/análise , Poaceae/química , Intoxicação/epidemiologia , Intoxicação/etiologiaRESUMO
Acetobacter diazotrophicus is a nitrogen-fixing bacterium that growth inside sugar cane plant tissue where the sucrose concentration is approximately 10%. The influence of high sugar content on nitrogenase was measured in the presence of oxygen and of nitrogen added in the form of ammonium and amino acids. In all parameters analyzed, 10% sucrose protected nitrogenase against inhibition by oxygen, ammonium, some amino acids, and also to some extent by salt stress. The oxygen concentration at which inhibition occurred increased from 2 kPa in 1% glucose or gluconic acid, to 4 kPa (0.4 atm) in 10% sucrose. Nitrogenase activity was partially inhibited by increased ammonium levels (2.0, 5.0, and 10.0 mM) in the presence of 1% sucrose, but the cells maintained their nitrogenase activity at 10% sucrose. This could be explained by the slow ammonium assimilation by the cells in the presence of high sucrose concentrations, i.e., independent of its concentration between 2 and 10 mM, the assimilation of ammonium was reduced to one-third in cells grown with 10% sucrose. Some amino acids were also tested in the presence of 1 and 10% sucrose. Cells grown in 1% sucrose had their nitrogenase activity reduced by 50-98% in the presence of glutamic acid, glutamine, alanine, asparagine, or threonine, whereas with 10% sucrose, nitrogenase activity was increased by glutamic acid and was reduced by only 61-73% by the other amino acids. The effect of NaCl concentrations (0.0, 0.25, 0.5, 0.75, or 1.0%) was also studied at the two concentrations of sucrose. Nitrogenase activity and growth of A. diazotrophicus, which was visualized by the pellicle formation in semi-solid medium, showed sensitivity even to low NaCl concentrations, which was somewhat relieved at the higher sucrose level. These observations indicate different osmotolerance mechanisms for sucrose and salt.
Assuntos
Acetobacter/efeitos dos fármacos , Proteínas de Bactérias/metabolismo , Nitrogenase/metabolismo , Sacarose/farmacologia , Acetobacter/enzimologia , Acetobacter/crescimento & desenvolvimento , Amônia/farmacologia , Meios de Cultura/química , Concentração Osmolar , Oxigênio/farmacologia , Cloreto de Sódio/farmacologiaRESUMO
[Pseudomonas] rubrisubalbicans, a mild plant pathogen. Herbaspirillum seropedicae, and EF group 1 strains (clustered by an immunological method) were investigated by a polyphasic approach with DNA-rRNA and DNA-DNA hybridizations and auxanography on 147 substrates. Our results show that they all belong to the genus Herbaspirillum. In addition to H. seropedicae, two other species are described: Herbaspirillum rubrisubalbicans and a new unnamed species, Herbaspirillum species 3, containing mainly strains of clinical origin. The three species can be differentiated on the basis of their auxanographic features and DNA-DNA similarities. The type strain of H. rubrisubalbicans is NCPPB 1027 (=LMG 2286); representative strains of the third Herbaspirillum species are strains CCUG 189 (=LMG 5523), CCUG 10263 (=LMG 5934), and CCUG 11060 (=LMG 5321). It has been confirmed that H. rubrisubalbicans is an endophytic diazotroph. It colonizes the roots, the stems, and predominantly the leaves of sugarcane (Saccharum spp.), while Herbaspirillum seropedicae colonizes in large numbers many different species of the Gramineae. Both diazotrophic Herbaspirillum species could be differentiated with meso-erythritol and N-acetylglucosamine. Oligonucleotide probes based on partial sequences of the 23S rRNA of H. seropedicae and H. rubrisubalbicans (HS and HR probes, respectively), were constructed and used as diagnostic probes.
Assuntos
Grão Comestível/microbiologia , Bactérias Aeróbias Gram-Negativas/classificação , Sequência de Bases , Sondas de DNA , Bactérias Aeróbias Gram-Negativas/isolamento & purificação , Dados de Sequência Molecular , Filogenia , Pseudomonas/classificação , Pseudomonas/isolamento & purificaçãoRESUMO
The first diagnosis of botulism in cattle in Brazil and its epizootiology are reviewed. The high prevalence of the disease raised on phosphorus deficient pastures in Savanna regions has caused severe economic losses in the past. The temperature induced microcomplement fixation test (TIMCF) confirmed the clinical-pathological diagnosis in all of the 24 cases studied by this method. The most important reason why botulism has not been controlled satisfactorily in Brazil is the lack of an available effective vaccine (type C and D). Additional prophylactic measures are phosphorus supplementation and removal of carcasses from the pasture.
Assuntos
Botulismo/veterinária , Doenças dos Bovinos/epidemiologia , Surtos de Doenças/veterinária , Animais , Vacinas Bacterianas/provisão & distribuição , Botulismo/epidemiologia , Brasil/epidemiologia , Bovinos , Clostridium botulinum/imunologia , PrevalênciaRESUMO
A sequence of research on "Cara inchada", a periodontal disease of young cattle (CI), involving heavy losses in Brazil, is described and results of laboratory investigations and field experiments are reported. A suspicion of being a primary nutritional disease of the skeleton could not be confirmed. In the other hand, bacteria, especially of the genus Bacteroides, were isolated from the periodontal CI-lesions. These bacteria possess enough pathogenic potential, through the production of enzymes and endotoxins, to cause primary destruction of the periodontal tissues. The lesions of the upper jaw, and also of the mandibula, of the diseased animals were diagnosed as a purulent periodontitis and a secondary ossifying alveolar periostitis. As CI occurs enzootically on new, cultivated pastures in cleared forest and savanna areas, and as the incidence of the disease declines with the years of pasture use, in order to disappear again, it can be postulated that a determining factor exists in the soil and consequently in the pasture, the disturbance of the equilibrium of the microflora in the formerly virgin soil possibly causes a modification of the flora of the rumen and the oral cavity, so that bacteria, as Bacteroides spp., present in the subgingival space, could dominate and become pathogenic. The frequent diarrhoea observed in calves affected by CI could be a consequence of the modification of the microflora in the digestive tract. Accordingly, CI could be considered as an infectious periodontitis of calves due to altered ecological soil conditions.
Assuntos
Infecções por Bacteroides/veterinária , Doenças dos Bovinos/etiologia , Distúrbios Nutricionais/veterinária , Doenças Periodontais/veterinária , Animais , Infecções por Bacteroides/complicações , Brasil , Bovinos , Distúrbios Nutricionais/complicações , Doenças Periodontais/etiologiaRESUMO
Membrane protein patterns in SDS-PAGE clearly characterized Azospirillum amazonense, A. brasilense, A. lipoferum, and Herbaspirillum seropedicae. Each species showed also a typical major band with approximate molecular weights (AMWs) of 44, 39.5, 35.5, and 37.5 Kdaltons for the four species respectively. Characteristic lighter bands with AMWs of 63.5 and 19 Kdaltons were shown by A. amazonense. Similar bands of 54, 24 and 24.5 Kdaltons were typical of A. brazilense, A. lipoferum and H. seropedicae, respectively. The three Azospirillum species showed four identical proteins in common, out of the six main proteins presented in SDS-PAGE; H. seropedicae had only two major proteins with one of them common to all three Azospirillum species. The data strongly favors the maintenance of Azospirillum and Herbaspirillum as valid generic taxa as well as supports the validity of the three Azospirillum species.
Assuntos
Proteínas de Membrana/ultraestrutura , Spirillum/ultraestrutura , Azospirillum brasilense/ultraestrutura , Eletroforese em Gel de Poliacrilamida , Proteínas de Membrana/isolamento & purificaçãoRESUMO
The pyrrolizidine alkaloids retrorsine, senecionine, integerrimine, neosenkirkine and florosenine were isolated from different Senecio spp. common in southern Brazil, Uruguay and Paraguay. Structure elucidation of these compounds was mainly accomplished by two-dimensional FT NMR techniques. Detailed interpretations of 1H-1H and 1H-13C NMR correlation spectra are given. The alkaloids neosenkirkine, integerrimine and florosenine were found in Senecio leptolobus De Candolle, retrorsine accompanied by senecionine in Senecio selloi (Spreng.) DC and Senecio cisplatinus Cabrera. In Senecio heterotrichus DC. integerrimine is accompanied by retrorsine. Investigations on pathology and histopathology of Senecio envenomation in Brazil are summarized.
Assuntos
Intoxicação por Plantas/veterinária , Plantas Tóxicas , Senécio/análise , Alcaloides/análise , Animais , Brasil , Cromatografia , Espectroscopia de Ressonância Magnética , Intoxicação por Plantas/etiologia , Alcaloides de Pirrolizidina/análise , América do SulRESUMO
Nine macrocyclic trichothecenes, thought to cause toxic effects in herbivors, were isolated from the Brazilian shrub Baccharis coridifolia. The structures of two new components, named miophytocene A and B, are described. Structure analysis was mainly accomplished by application of two-dimensional Fourier transform NMR techniques. The trichothecenes are most likely produced by the soil fungus Myrothecium verrucaria, which was isolated from soil samples around B. coridifolia. It is concluded that the plant is able to absorb and accumulate these mycotoxins. Histopathological studies on rabbits which received roridin E and A per os revealed mainly necrosis and hemorrhages of the mucosa of the colon and in the case of roridin A also of the caecum. Lethality in mice was generally low, intoxication proceeding slowly. It has to be considered, however, that all trichothecenes tested are practically insoluble in aqueous solutions and were applied as emulsions (i.p. and per os application). No trichothecenes or other toxic substances were detected from the Brazilian species Baccharis dracunculifolia, although slight toxic effects have been reported in cattle.
Assuntos
Intoxicação por Plantas/veterinária , Plantas Tóxicas/análise , Sesquiterpenos/intoxicação , Tricotecenos/intoxicação , Animais , Brasil , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Camundongos , Fungos Mitospóricos/metabolismo , Intoxicação por Plantas/patologia , Coelhos , Microbiologia do Solo , Tricotecenos/análiseRESUMO
Sixty-one strains of the root-associated nitrogen fixer Spirillum lipoferum exhibited a similar morphology in peptone--succinate salts medium: vibrioid cells having a diameter of 1.0 micrometer. When grown in broth the cells had a single polar flagellum, but when grown on agar at 30 degrees C lateral flagella of shorter wavelength were also formed. The DNA base composition was 69--71 mol% guanine + cytosine when determined by thermal denaturation. DNA homology experiments indicated the occurrence of two distinct but related homology groups: 46 strains were in group I and 15 strains were in group II. Group II strains were distinguished by their ability to use glucose as a sole carbon source for growth in nitrogen-free medium, by their production of an acidic reaction in a peptone-based glucose medium, by their requirement for biotin, and by their formation of wider, longer, S-shaped or helical cells in semisolid nitrogen-free malate medium. The results indicate that two species exist, and on the basis of their characteristics it is proposed that they be assigned to a new genus, Azospirillum. Strians belonging to group II are named A. lipoferum (Beijerinck) comb. nov., while those belonging to group I are named A. brasilense sp. nov. Strain Sp 59b (ATCC29707) is proposed as the neotype strain for A. lipoferum, and strain Sp 7 (ATCC 29145) is proposed as the type strain for A. brasilense.
Assuntos
DNA Bacteriano/análise , Spirillum/classificação , Meios de Cultura , Técnicas de Cultura , Microscopia Eletrônica , Microscopia de Contraste de Fase , Desnaturação de Ácido Nucleico , Spirillum/citologia , Spirillum/fisiologia , Terminologia como AssuntoRESUMO
Roots of field-grown tropical maize, Panicum maximum Jacq. and Digitaria decumbens Stent., and of sorghum and wheat grown in monoxenic culture with the diazotroph Spirillum lipoferum (syn. Azospirillum spp.) were examined for tetrazolium-reducing bacteria following incubation of roots in a malate-phosphate buffer-2,3,5-triphenyltetrazolium chloride medium. Bacteria were observed between and in cells of the cortex, in intercellular spaces between the cortex and endodermis, in xylem cells, and in and between pith cells. In maize, colonization of the inner cortex and stele appears to occur in the absence of significant bacterial colonization or collapse of outerlying tissues. Bacteria in the stele remained viable after a 6-h treatment of roots with chloramine-t, indicating that the endodermis was intact. Infection of the inner cortex and stele appears to occur initially in branches, and then to spread longitudinally into main roots. Inter- and intra-cellular infections of the cortex were observed in monoxenic systems. Tetrazolium reduction and prominent crystal formation was not specific for diazotrophic bacteria, but S. lipoferum was isolated from surface-sterilized roots, and S. lipoferum-like organisms were observed in the endorhizosphere. A correlation of inner cortex and stele infections with the presence of branches appears to explain previous observations that excised roots of grasses exhibiting high nitrogenase activity are characteristically branched roots with an intact cortex.
Assuntos
Bactérias/crescimento & desenvolvimento , Poaceae/microbiologia , Microbiologia do Solo , Zea mays/microbiologia , Bactérias/metabolismo , Brasil , Oxirredução , Poaceae/metabolismo , Spirillum/crescimento & desenvolvimento , Spirillum/metabolismo , Tetrazóis/metabolismo , Zea mays/metabolismoRESUMO
A survey in various countries revealed that the N2-fixing Spirillum lipoferum Beijerinck is a very common root and soil inhabitant in the tropics. More than half of the grass root and soil samples collected in tropical countries (four African countries and Brazil) contained abundant S. lipoferum populations, while less than 10% of the samples collected in temperate South Brazil, Kenya, and the U.S.A. contained the organism. There is a pronounced vegetation effect. Panicum maximum seems the most favorable among the forage grasses, while few positive samples were found under virgin tropical forest. Legume roots contained less S. lipoferum than adjacent soils. More than 80% of the samples from cereal roots (maize, sorghum, wheat, and rye) grown in fields fertilized with PK and Mo, in Rio de Janeiro State, were positive. Maize and sorghum grown under similar conditions in Wisconsin contained less than 10% of positive samples, but when maize fields were inoculated 90% of the root samples contained S. lipoferum. Alluvial soils were more favorable than eroded hill soils. Occurrence in soil was strongly pH-dependent with a pH around 7, being optimal (correlation coefficient r = 0.90). Sporadic occurrence was observed even in soils with pH 4.8. Surface-sterilized P. maximum roots collected from soils with pH ranging from 4.8 to 7.2 contained high S. lipoferum numbers which did not correlate with soil pH (r = 0.41). Amendment with malate of acid soils was not very effective in increasing nitrogenase (N2-ase) activity, but in two soils with pH above 6.4, high N2-ase activity was obtained after 16 to 48 h of incubation. In two soils from a temperate climate region, inoculation with S. lipoferum increased N2-ase activity produced through malate amendment.
Assuntos
Plantas/microbiologia , Microbiologia do Solo , Spirillum/isolamento & purificação , África , Brasil , Ecologia , Concentração de Íons de Hidrogênio , Fixação de Nitrogênio , Especificidade da Espécie , Spirillum/crescimento & desenvolvimento , Spirillum/metabolismo , Clima Tropical , Estados UnidosRESUMO
N(2) fixation in field-grown maize (Zea mays L.) plants was estimated by a nondestructive acetylene reduction method which permitted the plants to continue growing and produce seeds. Samples from six areas revealed mean nitrogenase activities of 74-2167 nmol of C(2)H(4)/(g of dry roots x hr) for 10 plants. Among 276 S(1) lines planted in two field experiments, 17 lines were selected for further nitrogenase activity assays after prescreening. Variability within lines was high but significant differences among lines were obtained in one experiment. The best lines showed mean nitrogenase activities of 2026, 2315, and 7124 nmol of C(2)H(4)/(g of dry roots x hr), whereas the original cultivar reduced only 313 nmol. The highest value approaches the nitrogenase activity of soybean. If the theoretical 3:1 (C(2)H(4)/N(2) reduced) conversion factor is used, a potential daily N(2) fixation of 2 kg of N(2)/hectare can be calculated. Periodic sampling within a brachytic maize cultivar revealed that maximum nitrogenase activity occurred at about the 75% silking stage. Soil effects also were pronounced. N(2)-fixing Spirillum sp. could be isolated from all active root pieces when they were surface sterilized. These organisms appear to be primarily responsible for root nitrogenase activity in maize.