Untersuchungen zum Vorkommen und zur gesundheitlichen ...

cell wall, these methods are time-consuming and require specific experience
normally not available in routine laboratories. For this reason, molecular
characterization (sequence analysis of the 16S rRNA gene) is recommended for
allocation of an unknown isolate at the genus- or genus group level.
The results of the project show, that even the genus identification of actinomycetes
will not be possible in most routine laboratories. Without molecular methods (16S
rRNA gene sequence) and the use of special chemotaxonomic methods,
identification is a very difficult task. No standardized, simple routine method can,
therefore, be recommended for the detection and identification of actinomycetes.
Nevertheless, the evaluation of the presence of actinomycetes in damp building
materials is an important question when dealing with indoor hygiene and a method
suitable for routine analysis is urgently needed. As a more simple approach it is,
therefore, suggested to restrict the detection of actinomycetes to those
actinomycetes growing with clearly visible mycelia on the Gauze mineral agar. The
result of this investigation should be recorded as “cfu mycelium-forming
actinomycetes” and it should be noted in the report that this parameter does only
include a certain part of the actinomycetes (mainly the genera Steptomyces,
Amycolatopsis, Nocardiopsis, Nocardia und Pseudonocardia). It should also be made
clear that no health risk evaluations can be derived from these data.
Toxicity tests:
Actinomycetes - and isolates of the genus Streptomyces in particular - can provoke
cytotoxic effects. Cytotoxic effects have been found for some actinomycetes and
damp building materials in the few and preliminary investigations with cell cultures in
this project. More detailed investigations are necessary to clearly show the relevance
of these results.
Spore suspensions of some actinomycetes and moulds can provoke proinflammatory
reactions on macrophages (release of TNF-α, immunomodulation effects). The
preliminary screening-investigations in this study showed, that different species of
microorganisms had different immunomodulation effects (TNF-α release), which
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