Untersuchungen zum Vorkommen und zur gesundheitlichen ...

species identification, however, a morphological, biochemical and chemotaxonomic
characterization and (in most cases) further studies (including DNA-DNA
hybridizations) are necessary.
A comprehensive experience with the different colony types of actinomycetes is
indispensable for successfully detect actinomycetes with the cultivation approach..
For this purpose, the different colony types of the most frequently found
actinomycetes must be studied on different cultivation media. This knowledge is a
prerequisite for a first grouping and selection of reference types of the different
actinomycete colonies for further studies.
For the isolation of actinomycetes from damp building material samples, the
supplementation of the cultivation media with an inhibiting agent for moulds is
necessary. Comparative studies on the suitability of cycloheximide and natamycin in
different concentrations led to the result, that the supplementation of 0.1 g/l
natamycin is most suitable for growth inhibition of molds.
Different actinomycetes have different growth requirements. For this reason it is not
possible to isolate all representatives of this diverse group on one single isolation
medium. In this study, the casein-mineral-agar (CMA), brain-heart-infusion-agar
(BHI), Tryptone soy-Agar (TSA = CASO) and the mineral agar according to Gauze
were found to be suitable to cover a broad range of different actinomycetes.
The appearance of different colony types and the morphological characteristics of
actinomycetes may be quite different on the different agar media. For the detailed
study of actinomycetes, which are able to form aerial mycelia and hyphae, the ISP2and
ISP3-agars are suitable, whereas actinomycetes, which do not form aerial
mycelia, should be studied on BHI-Agar and medium 79.
Color, form, and appearance of the colony as well as microscopic characteristics are
important for an initial characterization of an isolate and should preferentially be
recorded in a standardized form.
However, identification of actinomycetes is not possible on the basis of morphological
characteristics alone.. Chemotaxonomic studies can be very helpful for further
characterization, but with the exception of the analysis of the diaminoacid DAP in the
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