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ABSTRACT: Aerosolization of Bacteria, Archaea, Synergistes, Staphylococcus spp. and Propionibacterium acnes was investigated in situ with quantitative real-time PCR of DNA isolated from sludge and biogases of anaerobic digesters. The data revealed that in biogas, Staphylococcus spp. and P. acnes were, respectively, aerosolized 30 and 220 times more and Archaea and Synergistes, respectively, 8 and 20 times less aerosolized than Bacteria. This is the first demonstration of selective microbial aerosolization for anaerobic digestors microorganisms. This study illustrates the fact that some microbial groups, such as opportunistic pathogens, are more susceptible to be aerosolized, since they use air as a dissemination vector, and that this has to be taken in account when up-grading biogas into natural gas networks.
Bioresource technology 10/2010; 101(19):7252-7. · 4.25 Impact Factor
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ABSTRACT: The objective of this study was to identify fecal bacteria able to persist after wastewater treatment and that could be used as indicators of human fecal contamination. In a first step, the diversity of Bacteroidales, Clostridiaceae, Bifidobacterium, and Bacillus-Streptococcus-Lactobacillus cluster (BSL) was analysed using a fingerprint technique (CE-SSCP) and 16S rDNA libraries in waters collected at the end of the treatment process in different urban wastewater treatment plants. For each group, dominant bacteria present in most effluents were identified. Their origin (human feces, animal feces, non-fecal) was then analysed based on data of their closest relatives in public 16S rDNA databases. Among fecal bacteria recovered in the treated effluents analysed, phylotypes close to Bifidobacterium adolescentis and Bacteroides caccae seem to be specific to human beings. Phylotypes gathering only sequences of human fecal origin were also identified among the BSL and Clostridiaceae, two bacterial groups which have been poorly investigated for bacterial source-tracking purpose. Since these bacteria were detected post-treatment in most wastewater treatment plants, they may constitute potential new indicators of fecal contamination specific to humans that could be used to track fecal contamination of surface water by sewage.
Water Research 11/2009; 44(6):1873-83. · 4.86 Impact Factor
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ABSTRACT: This article outlines a comprehensive analysis of the microbial diversity of aerosols produced during screening in a green waste composting plant using both culture and molecular techniques. Bacteria, thermophilic actinomycetes and fungi were quantified in the aerosols. The structure of the microbial community was examined using a fingerprint technique and DNA libraries. The results show: (i) the very high diversity of bacteria and fungi in aerosols produced during the composting screening stage, (ii) the low percentage of cultivability for bacteria in aerosols, (iii) the abundance of Thermoactinomyces spp. and Aspergillus spp. in compost aerosols.
Current Microbiology 07/2009; 59(3):326-35. · 1.82 Impact Factor
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ABSTRACT: The dynamics of Legionella spp. and of dominant bacteria were investigated in water from a cooling tower plant over a 9-month period which included several weeks when Legionella pneumophila proliferated. The structural diversity of both the bacteria and the Legionella spp. was monitored by a fingerprint technique, single-strand conformation polymorphism, and Legionella spp. and L. pneumophila were quantified by real-time quantitative PCR. The structure of the bacterial community did not change over time, but it was perturbed periodically by chemical treatment or biofilm detachment. In contrast, the structure of the Legionella sp. population changed in different periods, its dynamics at times showing stability but also a rapid major shift during the proliferation of L. pneumophila in July. The dynamics of the Legionella spp. and of dominant bacteria were not correlated. In particular, no change in the bacterial community structure was observed during the proliferation of L. pneumophila. Legionella spp. present in the cooling tower system were identified by cloning and sequencing of 16S rRNA genes. A high diversity of Legionella spp. was observed before proliferation, including L. lytica, L. fallonii, and other Legionella-like amoebal pathogen types, along with as-yet-undescribed species. During the proliferation of L. pneumophila, Legionella sp. diversity decreased significantly, L. fallonii and L. pneumophila being the main species recovered.
Applied and environmental microbiology 06/2008; 74(10):3030-7. · 3.69 Impact Factor
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ABSTRACT: Two enteric pathogens, Salmonella spp. and Campylobacter jejuni, and two bacteria commonly used as indicators, Escherichia coli and Clostridium perfringens, were monitored using quantitative real-time PCR during municipal wastewater treatment and sludge composting. The results were compared with those obtained using standard culture methods. A reduction of all bacteria was observed during wastewater treatment and during the thermophilic phase of composting. However, the bacterial groups studied behaved differently during the process, and the main differences were observed during biological treatment in activated sludge basins. In particular, Salmonella spp. and C. jejuni survived better during activated sludge treatment than E. coli. C. jejuni was the most resistant to wastewater treatment among the four bacterial groups. Overall, differences in survival were observed for all bacteria studied, when submitted to the same environmental pressure. This holds both for differences between indicators and pathogenic bacteria and between pathogenic bacteria. These results show the difficulty in defining reliable indicators.
Water Research 02/2008; 42(1-2):53-62. · 4.86 Impact Factor
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ABSTRACT: Previously, we showed that prenatal exposure to boric acid (BA), an industrial agent with large production, causes alterations of the axial skeleton in rat embryos, reminiscent of homeotic transformations. Indeed, Sprague-Dawley rats exposed in utero to BA on gestation day 9 (GD 9) had only six, rather than the normal seven, cervical vertebrae. This finding, observed in 91% of GD 21 fetuses, suggests posterior transformations of vertebrae. The present study attempts to determine if these skeletal alterations could be explained by modifications of the hox code, involved in the establishment of positional information along the craniocaudal axis of the embryo.
Pregnant rats were treated by gavage with BA (500 mg/kg, twice) on GD 9. Embryos were collected on GD 11 or GD 13.5 and processed for in situ hybridization. Several hox genes were selected according to the position of their cranial limit of expression in the cervical and thoracic region.
At GD 13.5, we detected a cranial shift of the anterior limit of expression of hoxc6 and hoxa6. We observed no difference between control and treated embryos in the location of the cranial limit of expression of the other genes: hoxd4, hoxa4, hoxc5, and hoxa5.
Our results demonstrate that following in utero exposure to BA on GD 9, a disturbance of the expression of hox genes involved inthe specification of most anterior vertebrae is observed at GD 13.5. Based on their expression domain and on their implication in the definition of the cervicothoracic vertebral boundary, it is likely that the anteriorization of hoxc6 and hoxa6 reported here is correlated to the morphological phenotype observed in BA-exposed fetuses at GD 21.
Birth Defects Research Part A Clinical and Molecular Teratology 02/2003; 67(1):59-67. · 2.27 Impact Factor
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ABSTRACT: Several embryotoxic agents, which includes sodium salicylate, were reported to induce vertebral variations in the form of supernumerary ribs (SNR) when administered to pregnant rodents. Because the biological significance of SNR in toxicological studies is still a matter of debate, we investigated the molecular basis of this defect by analyzing the possible involvement of Hox genes, known to specify vertebrae identity. Sodium salicylate (300mg/kg) was administered to pregnant rats on gestational day 9 (GD 9). On GD 13, the expression of several Hox genes, selected according to the position of their anterior limit of expression, namely upstream (Hoxa9), at the level (Hoxa10) and downstream (Hoxd9) to the morphological alteration, were analyzed. Posterior shifts in the anterior limit of expression of Hoxa10 and Hoxd9 were observed following exposure to salicylate, which could explain an effect at the level of the axial skeleton. This finding suggests that the appearance of ectopic ribs can be attributed to an anterior transformation of lumbar vertebrae identity into thoracic vertebrae identity. Whether this transformation occurs with all compounds inducing SNR in rats remains to be determined.
Reproductive Toxicology 20(1):39-45. · 3.23 Impact Factor
