Fungal and microbial volatile organic compounds exposure assessment in a waste sorting plant.

In the management of solid waste, pollutants over a wide range are released with different routes of exposure for workers. The potential for synergism among the pollutants raises concerns about potential adverse health effects, and there are still many uncertainties involved in exposure assessment. In this study, conventional (culture-based) and molecular real-time polymerase chain reaction (RTPCR) methodologies were used to assess fungal air contamination in a waste-sorting plant which focused on the presence of three potential pathogenic/toxigenic fungal species: Aspergillus flavus, A. fumigatus, and Stachybotrys chartarum. In addition, microbial volatile organic compounds (MVOC) were measured by photoionization detection. For all analysis, samplings were performed at five different workstations inside the facilities and also outdoors as a reference. Penicillium sp. were the most common species found at all plant locations. Pathogenic/toxigenic species (A. fumigatus and S. chartarum) were detected at two different workstations by RTPCR but not by culture-based techniques. MVOC concentration indoors ranged between 0 and 8.9 ppm (average 5.3 ± 3.16 ppm). Our results illustrated the advantage of combining both conventional and molecular methodologies in fungal exposure assessment. Together with MVOC analyses in indoor air, data obtained allow for a more precise evaluation of potential health risks associated with bioaerosol exposure. Consequently, with this knowledge, strategies may be developed for effective protection of the workers.

Global gene expression changes underlying Stachybotrys chartarum toxin-induced apoptosis in murine alveolar macrophages: evidence of multiple signal transduction pathways.

The overall mechanism(s) underlying macrophage apoptosis caused by the toxins of the indoor mold Stachybotrys chartarum (SC) are not yet understood. In this direction, we report a microarray-based global gene expression profiling on the murine alveolar macrophage cell line (MH-S) treated with SC toxins for short (2 h) and long (24 h) periods, coinciding with the pre-apoptotic (<3 h) and progressed apoptotic stages of the treated cells, respectively. Microarray results on differential expression were validated by real-time RT-PCR analysis using representative gene targets. The toxin-regulated genes corresponded to multiple cellular processes, including cell growth, proliferation and death, inflammatory/immune response, genotoxic stress and oxidative stress, and to the underlying multiple signal transduction pathways involving MAPK-, NF-kB-, TNF-, and p53-mediated signaling. Transcription factor NF-kB showed dynamic temporal changes, characterized by an initial activation and a subsequent inhibition. Up-regulation of a battery of DNA damage-responsive and DNA repair genes in the early stage of the treatment suggested a possible role of genotoxic stress in the initiation of apoptosis. Simultaneous expression changes in both pro-survival genes and pro-apoptotic genes indicated the role of a critical balance between the two processes in SC toxin-induced apoptosis. Taken together, the results imply that multiple signaling pathways underlie the SC toxin-induced apoptosis in alveolar macrophages.