RESUMEN
The statement presented here gives an overview and assessment of the procedures and concepts currently used for the collection and determination of airborne, culturable microorganisms at sources of emission within composting plants and in their near vicinity. The paper focuses on "classical" methods, which involve cultivation as an intermediate step for the determination of viable, airborne microorganisms. The theoretical and practical requirements on such methods are discussed. Results and experiences from recent investigations are described.
Asunto(s)
Microbiología del Aire , Contaminantes Ocupacionales del Aire , Técnicas Bacteriológicas , Eliminación de Residuos , Monitoreo del Ambiente , HumanosRESUMEN
In order to assess source emissions and dispersal of airborne culturable microorganisms from composting plants, measurements at three composting plants have been carried out. The downwind concentrations of dispersed microorganisms differed greatly, depending on the type of plant design. At 200 metres downwind from the totally enclosed composting plant, levels of spore concentrations of thermotolerant fungi and Aspergillus fumigatus, which may be regarded as characteristic for composting operations, were not above the magnitude of background concentrations. In contrast, spore concentrations in excess of the background level occurred within 500 metres of the partly open plant. Moreover, the ranges of airborne concentrations at similar distances from the enclosed plant were much smaller relative to the partly open plant. Measurement of source emissions from biofilters showed concentrations in the raw and purified gases in the range of up to three orders of magnitude. The operational characteristics of the plants generally contributing to bioaerosol emissions on-site were found to have an influence on the concentration levels in the raw gas. A decrease in the microbiological parameters which may be regarded as specific for composting operations, was attributed to a reduced rate of passage through the biofilters. The magnitude of reduction as well as the concentrations varied greatly.
Asunto(s)
Microbiología del Aire , Monitoreo del Ambiente , Filtración , Eliminación de Residuos , Recuento de Colonia Microbiana , Hongos/aislamiento & purificación , Alemania , HumanosRESUMEN
Hydrophobic adhesion of cells of the black yeast Hortaea werneckii (Horta) Nishimura & Miyaji, causative agent of human tinea nigra, was established by microbial adhesion to hexadecane (MATH) and adhesion to polystyrene, and compared with adhesion of other species of black yeasts. Additional ecophysiological tests were performed. Hortaea werneckii cells proved to have a high degree of hydrophobicity (98.5% MATH). The species is unable to degrade keratin, but shows significant lipolytic activity. It is concluded that H. werneckii is a commensal, that shows lipophilic adhesion to human skin and survives by the assimilation of excretion products.
Asunto(s)
Membrana Celular/fisiología , Lipólisis , Tiña/microbiología , Levaduras/fisiología , Animales , Adhesión Celular , Humanos , Piel/microbiología , Levaduras/clasificación , Levaduras/aislamiento & purificaciónRESUMEN
A strain of the black yeast Exophiala dermatitidis displayed a hydrophobic synanamorph consisting of acropetal chains of lemon-shaped conidia, morphologically similar to those of Cladophialophora bantiana. The occurrence of the two conidial types in a single strain suggests a taxonomic affinity between Exophiala and Cladophialophora and provides support to the supposition that Cladophialophora, a possible anamorph genus of Herpotrichiellaceae, is related to black yeasts rather than to Cladosporium, which has teleomorphs in the Mycosphaerellaceae.
Asunto(s)
Exophiala/citología , Exophiala/clasificación , HumanosRESUMEN
The anamorph life cycle of the black yeast Exophiala (Wangiella) dermatitidis is described. The fungus is dimorphic, yeast cells being the prevalent form of propagation. The fungus is strongly hydrophilic, probably completing its anamorph life cycle in submersion. Adaptation to dry conditions is slow. Types of conidiogenesis comprise annellidic, phialidic and sympodial reproduction, in addition to isotropic development. Phialoconidia fail to germinate under the conditions tested, and thus may have a function other than dispersal. Sterile, multicellular bodies resembling a Capronia teleomorph are described.