Retreatment of silicon slurry by membrane processes.

The purpose of the present study is to develop a process to regenerate the polish liquid used in Chemical and Mechanical Polishing (CMP), called "slurry", and more specifically Silicon CMP slurry. Physico-chemical analyses show a considerable dilution of slurry through washing waters used in polishing. Thus, this effluent has been characterised for a better identification of the deviations from the slurry of reference (Point Of Use). Hence, the principle is to regenerate this effluent by membrane processes. The ultrafiltration results obtained at laboratory scale have led to the development of an industrial prototype. An optimal utilisation of this treatment allows completing a two-step process: the reconcentration by ultrafiltration and a chemical adjustment by addition of concentrated slurry. A stable behaviour of the slurry at the different steps of the process has been observed. Polishing results are similar with retreated and POU slurries. Furthermore, the functioning at industrial scale permits to maintain the performances obtained on the laboratory pilot.

Discharge of pharmaceutical products (PPs) through a conventional biological sewage treatment plant: MECs vs PECs?

Pharmaceuticals for human use are consumed in significant quantities and their occurrence in aquatic systems has been reported by a number of authors. In the context of environmental risk assessment, there is an increasing interest in evaluating the discharge of pharmaceutical products to surface waters through sewage treatment plants (STP). This case study was carried out on a conventional biological treatment plant (Alès, France) and focused on a set of eleven drugs representing the main therapeutic classes. Measured environmental concentrations (MECs) range from the low ng L(-1) to 1.5 microg L(-1) in effluent and up to few hundred ng L(-1) in receiving surface waters. There is a good agreement between MEC and predicted environmental concentration (PEC) values for seven of the eleven investigated drugs in STP effluent. There is not such a good match between PEC and MEC values in surface waters, and this highlights the limits of this approach, at the local scale.

Efficient method to isolate and purify viruses of bacteria from marine environments.

AIM: To isolate viruses of specific heterotrophic bacterial strains from marine environments using a host addition/virus amplification protocol (HAVAP) for use in phage/host systems. METHODS AND RESULTS: Bacteria-free seawater samples containing natural viruses assemblages were inoculated with a single laboratory grown bacterial host of interest in a nutrient-enriched [peptone, Fe(III) and yeast extract] seawater suspension. These conditions enhanced the replication of only those virus(s) capable of infecting the host bacterium. After incubation, free viruses were recovered at concentrations ranging 10(5)-10(10) infectious virus particles per ml of seawater. Using this approach, 15 viruses were isolated and represented 12 unique phage/host systems. Two of the hosts tested were infected by more than one virus. CONCLUSIONS: Isolation of high concentrations of specific viruses is possible even if their initial concentrations in native waters are low. This approach allows the recovery of phage/host systems that may not be numerically dominant. SIGNIFICANCE AND IMPACT OF THE STUDY: This host enrichment protocol for virus detection and isolation is well-suited for aquatic viral ecology studies that require phage/host systems.

Duplex PCR for differential identification of Mycobacterium bovis, M. avium, and M. avium subsp. paratuberculosis in formalin- fixed paraffin-embedded tissues from cattle.

We previously isolated and sequenced two genomic segments of Mycobacterium avium subsp. paratuberculosis, namely, f57, a species-specific sequence, and the p34 gene, coding for a 34-kDa antigenic protein. Comparison of sequences upstream of the p34 open reading frame (us-p34) from M. avium subsp. paratuberculosis and M. tuberculosis showed a 79-base deletion in M. tuberculosis. Sequence analysis of the p34 genes in another two species, M. bovis (strain BCG) and M. avium (strain D4), confirmed the differences observed between tuberculous and nontuberculous species. A duplex diagnostic PCR strategy based on coamplification of nonhomologous us-p34 and species-specific f57 sequences was therefore developed. Duplex PCR yielded three different patterns, specific either for tuberculous bacilli (M. tuberculosis, M. bovis, and M. africanum), for both nontuberculous mycobacteria M. avium and M. intracellulare, or for M. avium subsp. paratuberculosis. The specificity of this single-step DNA-based assay was assessed on DNA from cultured mycobacterial strains, as well as on a panel of formalin-fixed and paraffin-embedded tissues from cattle. Molecular assay results from tissular DNA were compared to conventional bacteriological and histological test results, including those obtained by Ziehl-Neelsen staining on tissue biopsy specimens. Molecular discrimination was successful and confirmed the value of duplex us-p34 and f57 sequence amplification for differential diagnosis of tuberculosis, paratuberculosis, or infections caused by other members of the M. avium complex.

Detection of Mycobacterium avium subsp. paratuberculosis in infected tissues by new species-specific immunohistological procedures.

We have previously described the cloning and sequencing of a gene portion coding for the terminal part of a 34-kDa protein of Mycobacterium avium subsp. paratuberculosis, the etiological agent of Johne's disease (P. Gilot, M. De Kesel, L. Machtelinckx, M. Coene, and C. Cocito, J. Bacteriol. 175:4930-4935, 1993). The recombinant polypeptide (a362) carries species-specific B-cell epitopes which do not cross-react with other mycobacterial pathogens (M. De Kesel, P. Gilot, M.-C. Misonne, M. Coene, and C. Cocito, J. Clin. Microbiol. 31:947-954, 1993). The present work describes the preparation of polyclonal and monoclonal antibodies directed against a362 and the use of these immunoglobulins for histopathological diagnosis of Johne's disease. The new immunohistological procedures herewith detailed proved to be able to identify M. avium subsp. paratuberculosis antigens in the intestinal tissues and lymph nodes of cattle affected by either the paucibacillary or pluribacillary form of the disease. They yielded negative responses not only with healthy animals but also with those affected by tuberculosis (Mycobacterium bovis). Both immunohistological procedures proved to be as sensitive as or more sensitive than Ziehl-Neelsen staining and, in addition, to be endowed with species specificity.

Immunological analysis of the components of the antigen complex A60 of Mycobacterium bovis BCG.

The antigen complex of A60 of Mycobacterium bovis BCG was analyzed by different immunological techniques to assess its relevance to tuberculosis and the involvement of its components in the immune reactions elicited in humans by tuberculous infection. A60 is composed of about 30 components, of which 8 were identified by available monoclonal antibodies (lipoarabinomannan, a glycolipid, and proteins of 65, 40, 38, 35, 19, and 14 kDa). The majority (87.5%) of anti-mycobacterial antibodies in sera from tuberculosis patients was directed against A60. Western blot (immunoblot) analysis indicated that the majority of the highly antigenic proteins present in mycobacterial homogenates were components of the A60 complex. A small percentage (7.8%) of A60 epitopes proved to be species specific. Thus, A60 proteins of 66, 41, 38, 37, 35, 34, 32, and 22 kDa were found to contain B-cell epitopes specific for M. bovis and not shared by Mycobacterium leprae oR Mycobacterium avium.