Influence of buffer systems on Trichoderma reesei Rut C-30 morphology and cellulase production

The cellulase enzyme production is a key issue in the enzymatic hydrolysis of lignocellulosic materials. Since fungal morphology influences the productivity of fungal fermentations, it is of major importance to well know the fungal behavior during culture for cellulase production. In this work, the influence of medium supplementation, with different buffer systems at two different concentrations and pH conditions, on the morphology of T. reesei Rut C-30 and cellulase production, was investigated. A medium without buffer was used as control. The results suggest that fungal morphology is significantly dependent on the addition of different buffer systems to the nutrient broth. The mycelial morphology shows a clear transition from clumped to pelleted forms in cultures with variation of buffer systems and concentration. The higher filter paper activity was obtained using 100 mM succinate buffer, at pH 4.8, in the medium supplementation, corresponding to a dispersed mycelial morphology.

Prevalence of dermatophytes and other fungal agents isolated from clinical samples.

The common cause of skin infections are dermatophytes and opportunistic fungi. Aim of this study was to isolate and identify the fungal agents from clinical samples from patients with different mycoses. Clinical samples from 165 patients were subjected to potassium hydroxide (KOH) examination and culture isolation; causative agents were identified macroscopically and microscopically. All the 165 specimens were KOH positive and 110/165 (66.7%) samples were culture positive. Of these, highest isolation rate was obtained in opportunistic mycoses such as candidiasis (29/29, 100%). Dermatophytes were isolated in 53/80 (66.3%) specimens and Trichophyton rubrum was the commonest isolate in skin samples (17/24) among the patients suffering from dermatophytosis. Phaeoannellomyces wernecki was isolated in a patient suffering from tinea nigra. The study signifies the importance of mycological examination in the diagnosis of various mycoses for their effective management.

Cell signaling pathways in Paracoccidioides brasiliensis: inferred from comparisons with other fungi

The human fungal pathogen Paracoccidioides brasiliensis is an ascomycete that displays a temperature-dependent dimorphic transition, appearing as a mycelium at 22 degrees C and as a yeast at 37 degrees C, this latter being the virulent form. We report on the in silico search made of the P. brasiliensis transcriptome-expressed sequence tag database for components of signaling pathways previously known to be involved in morphogenesis and virulence in other species of fungi, including Saccharomyces cerevisiae, Cryptococcus neoformans, Candida albicans, and Aspergillus fumigatus. Using this approach, it was possible to identify several protein cascades in P. brasiliensis, such as i) mitogen-activated protein kinase signaling for cell integrity, cell wall construction, pheromone/mating, and osmo-regulation, ii) the cAMP/PKA system, which regulates fungal development and virulence, iii) the Ras protein, which allows cross-talking between cascades, iv) calcium-calmodulin-calcineurin, which controls cell survival under oxidative stress, high temperature, and membrane/cell wall perturbation, and v) the target of rapamycin pathway, controlling cell growth and proliferation. The ways in which P. brasiliensis responds to the environment and modulates the expression of genes required for its survival and virulence can be inferred through comparison with other fungi for which this type of data is already available.

Aspectos morfológicos y moleculares (ITSrDNA) en especies del gÚnero Ulocladium de suelos desÚrticos: Únfasis en el grupo U. atrum / Morphological and molecular aspects (ITSrDNA) in species of genus Ulodcladium collected from desertic soils: Emphasis in U. atrum group

En este estudio, se empleó la morfología y la biología molecular como herramientas taxonómicas, para corraborar su aplicabilidad en 38 cepas del genero Ulocladium Preuss, obtenidas de zonas cercanas al Salar de Atacama, entre altitudes de 2.200 a 4.500 m.s.n.m. y clasificadas morfologicamente con anterioridad a nuestra investigación bajo la nominación de: U.alternariae, U.atrum, U.botrytis, U.chartarum, U.consortiale y U.tuberculatum. en todas ellas se aplicaron 2 protocolos: a) extracción de DNA, amplificación con 2 partidores para ITS, y digestión con las enzimas Hinf I y Rsa I para ver su aplicabilidad en la separación de las especies, y b) para los representantes del taxon U.atrum (especie dominante), se analizó la conidiogenesis de 15 cepas en cultivo con agar papa zanahoria, en fases tempranas y tardías de su crecimiento, según lo descrito por Simmons (1998), que considera a esta especie como un grupo posible de separar en cuatro nuevos taxa. En los estudios del genotipo, la electroforesisen gel de poliacrilamida de los productos de digestión, no presentaron patrones de migración que permitieran distinguir molecularmente las 6 especies en estudio ni separar a los integrantes del grupo U.atrum, pero los analisis morfológicos de este grupo, representaroin ecotipos con ciertas características distintivas, con una población de dimensiones conidiales mßs reducidas, globosas a subglobosas en sus formas juvenilews y tardías, ademßs ciertos integrantes puieden considerarse como nuevos morfotipos. dentro del grupo, U.atrum s.str., fue representado mayoritariamente, una cepa correspondió a U.multiforme y otra se consideró fuera del grupo.

Cromomicosis: informe de cinco casos con énfasis histopatológico y terapéutico / Chromomycosis: report of five cases with emphasis terapeutic and histopathological

La cromomicosis es una micosis subcutánea y cutánea crónica que predomina en las áreas tropicales y subtropicales. Determinar las características epidemiológicas, clínicas e histopatológicas de los pacientes diagnosticados como cromomicosis; con énfasis en los datos histopatológicos y terapéuticos. Se informan cinco pacientes estudiados entre 1987 y 1997; 3 hombres y dos mujeres con una evolución promedio de 15,8 años. La topografía fue extremidades inferiores y superiores, y un caso diseminada a cara, tronco y extremidades superiores, manifestándose en todos los casos como placas verrucosas. En todos los casos se aisló Fonsecaea pedrosoi. En cuanto a distribución geográfica, 2 pacientes eran de Oaxaca y el resto de Puebla, Tamaulipas y Chiapas respectivamente. En el estudio histopatológico se demostraron cambios proliferativos en la epidermis, constituidos por acantosis e hiperplasia pseudoepiteliomatosa aguda y crónica; así como proliferación vascular y fibrosis: Se pudieron observar células fumagoides tanto dentro de células gigantes multinucleadas, en forma libre, como en los microabscesos de neutrófilos. Las modalidades terapéuticas se basaron en su mayoría en la combinación de procedimientos médicos y quirúrgicos. Debido al número de pacientes incluidos en este estudio, solo podemos describir las características clínicas, histopatológicas y etiología de la cromomicosis. Así mismo podemos concluir que no existe un tratamiento de elección, y que la combinación de procedimientos quirúrgicos y médicos siguen siendo la mejor opción en la cromomicosis

Actin cytoskeleton structure and its localization in gongronella butleri, mucor javanicus and absidia cylindrospora (mucorales-zygomycetes)

Mediante estudios de microscopia òptica de fluorescencia se describe y caracteriza la estructura, distribución y localización de la actina, en tres especies de hongos de la clase zygomycetes: absidia cylindrospora, gongronella butleri y mucor javanicus. La estructura de la actina fué analizada utilizándose el marcador fitc-phalloidina, especifico para actina, en muestras fijadas con formaldehido. En los resultados se observan diferencias en la estructura, distribución y localización de esta proteina en las especies analizadas. Filamentos , aglomerados, placas o aglomerados periféricos y gránulos, fueron las formas más comunes encontradas en los hongos, con prevalencia de los aglomerados observados en todos los citoplasma de las hifas. La tinción de actina en losápices de las hifas, solo se observó en mucor javanicus, esta diferencia en la estructura de la actina podría estar asociada a zonas de expansión de la pared celular de los hongos

Morphological, cytological, and cultural aspects of Curvularia pallescens

Curvularia pallescens Boedijn (Hyphomycetes) is redescribed with the aid of scanning electron microscope, and the optimal cultural conditions for growing this fungus are discussed. Cytological analysis and nuclear condition, observed through the HCl-GIEMSA techique, showed vegetative and reproductive structures (hypha and conidia) formed by uni, bi, tri, and multinucleated segments. Cultures of C. pallescens in Complete Medium and in Potato Dextrose Agar varied on growth, on aspects of the border of the colonies and also on medium pigmentation. The Complete Medium and the temperature between 25-28degreeC were the most indicated for growth of C. pallescens.

Early diagnosis of mycotic keratitis: predictive value of potassium hydroxide preparation.

Potassium hydroxide (KOH) preparation is an underutilized modality in the diagnosis of mycotic keratitis. We have earlier shown its utility in the diagnosis of Nocardia and Acanthamoeba keratitis. The aim of this study was (i) to evaluate the sensitivity, specificity and predictive value of KOH preparation, and (ii) to compare its efficacy with other methods of corneal scraping examination, for the diagnosis of mycotic keratitis. The study was conducted in two phases. In phase I, randomized corneal scrapings were examined by KOH, Gram's stain, and lactophenol cotton blue (LPCB) in 91 infectious keratitis subjects. In phase II, 53 corneal scrapings were stained with KOH and calcofluor white (CFW), and viewed with bright field (KOH) and fluorescence (CFW) microscopy. The KOH and CFW readings were recorded by an observer masked to the clinical findings and culture results. Nineteen scrapings were examined by two masked observers. In 22 culture positive fungal keratitis patients in phase I, the sensitivity of KOH, Gram's stain, and LPCB methods was 100%, 86.4%, and 77.3%, respectively. In phase II, the specificities of KOH and CFW were identical (83.8%), while the sensitivities were 81.2% and 93.7%, respectively (p = 0.59), in 16 culture positive mycotic keratitis patients. There was no significant difference between the negative and positive predictive values of KOH and CFW. Furthermore, no significant interobserver variability was found in the specificity and sensitivity. The KOH method compares well with other microscopy methods in the diagnosis of keratomycosis and has a definite place in the armamentarium of diagnostic techniques.

Recuperaçäo de Candida Albicans, C. Tropicalis, C. Guilliermondii e C. Krusei na cavidade bucal de ratos normais e sialodenectomizados / Candida albicans, C. tropicalis, C. guilliermondii and C. krusei recovery in control and sialoadenectomized rats oral cavity

A permanência de Candida albicans, C. tropicalis, C. guilliermondii e C. Krusei na cavidade bucal de ratos foi estudada em animais normais e sialoadenectomizados. Os ratos foram inoculados por 4 dias consecutivos com 10 leveduras, e após 1, 5, 15 e 30 dias da inoculaçäo foi feita a recuperaçäo das amostras da cavidade bucal dos animais. Em ambos os grupos, C. albicans foi isolada em maior quantidade em todos os períodos. C. guilliermondii, C. tropicalis e C. Krusei foram recuperadas em menor quantidade, näo sendo mais isoladas a partir do 5º dia após a inoculaçäo. A xerostomia facilitou a colonizaçäo de C. albicans, mas näo das outras espécies. Os dados obtidos no presente trabalho sugerem o envolvimento de fatores relacionados à C. albicans, que determinaram sua maior colonizaçäo na boca dos ratos, o que pode indicar seu maior grau de patogenicidade

Laboratory evaluation of sensitivity of three keratinophilic fungi to some vicolides.

Four vicolides (sesquiterpenoides) isolated from Vicoa indica were evaluated against three keratinophilic fungi, viz., Microsporum gypseum, Chrysosporium tropicum, and Trichophyton terrestris. All the test fungi were found to be sensitive to vicolides. Vicolides A and C showed the maximum efficacy while B and D exhibited moderate activity. The Minimum Inhibitory Concentration (MIC) was observed in the range of 15.62-125 micrograms. The most sensitive fungus tested was C. tropicum followed by T. terrestris and M. gypseum.

Studies on isolation and regeneration of protoplast of thermophilic fungus Malbranchea Pulchella VAR. sulfurea

Protoplastos esféricos osmoticamente sensíveis foram isolados de micélio do fungo termofílico Malbranchea pulchella var. sulfurea pela açäo de enzima extracelular (Novozym 234) sobre a parede das células. Estäo descritas as condiçöes para obtençäo de protoplastos estáveis a partir do micélio. O uso de KCL 0,6M como estabilizador osmótico permitiu a liberaçäo do número máximo de protoplastos. A maior parte dos protoplastos foram liberados a partir de micélios cultivados por 96 - 148 h, embora micélios mais jovens liberassem protoplastos mais estáveis e maiores em tamanho. Determinou-se, também, a açäo da enzima sobre a superfície do micélio. O número máximo de protoplastos foi observado em pH 5,5. Estudaram-se também as condiçöes requeridas para a regeneraçäo dos protoplastos

Observaçöes citológicas em conídios e células miceliais de humicola sp / Cytological observations in conidial and mycelial cells of humicola sp

Resumo: O objetivo desse estudo foi descrever aspectos do comportamento nuclear durante a divisäo miótica em conídios e células miceliais do fungo celulolítico Humicola so. A sequência dos eventos mitóticos foi similar aquela observada em outros fungos filamentosos. O número de cromossomos observados no final da metáfase näo pode ser determinado com segurança, mas pareceu estar entre 6 e 8. As culturas de Humicola sp frequentemente mostraram anastomose de hifas e a presença de núcleos na ponte hifal, o que permitiria a ocorrência de heterocariose,e indica que o ciclo parasexual pode ocorrer nessa espécie (au)