Microbial diversity and community composition in recirculating vertical flow constructed wetlands.

Microorganisms constitute a central component of constructed wetlands (CWs), playing a major role in these systems' capacity for treating wastewater. The aim of this study was to determine the diversity and composition of the microbial community found in a recirculating vertical flow CW (RVFCW) bed fed with primarily settled domestic wastewater and its response to the presence of plants, season and location in the bed. The RVFCW removed 90-95% of TSS and BOD(5) to below 10 mg L(-1). The effluent quality was not significantly affected by seasonal temperature or the existence of plants in the bed. None of these factors had discernible effects on bacterial diversity, e.g. in the planted RVFCW, the richness (S') and Shannon-Weiner diversity (H') indices were 18.3 (±3.5) and 2.49 (±0.15), respectively, which are similar to the values of 19.4 (±3.5) and 2.57 (±0.18) in the unplanted RVFCW. However, there were indications that the structure of the microbial community underwent changes that were uncorrelated with the environmental factors tested and that did not affect the overall performance. The consistency in diversity and composition/structure of the bacterial community in the face of temporal and environmental influences possibly contributes to the robustness and high treatment capacity of the RVFCW system.

The dual role of bacteriocins as anti- and probiotics.

Bacteria employed in probiotic applications help to maintain or restore a host's natural microbial floral. The ability of probiotic bacteria to successfully outcompete undesired species is often due to, or enhanced by, the production of potent antimicrobial toxins. The most commonly encountered of these are bacteriocins, a large and functionally diverse family of antimicrobials found in all major lineages of Bacteria. Recent studies reveal that these proteinaceous toxins play a critical role in mediating competitive dynamics between bacterial strains and closely related species. The potential use of bacteriocin-producing strains as probiotic and bioprotective agents has recently received increased attention. This review will report on recent efforts involving the use of such strains, with a particular focus on emerging probiotic therapies for humans, livestock, and aquaculture.

Monitoring of phosphorus bioavailability in water by an immobilized luminescent cyanobacterial reporter strain.

Massive growth of cyanobacteria, known as "algal blooms", has become a major concern for water monitoring. It has been observed that environmental factors like temperature, light, and certain patterns of availability of nutrients such as P, N, Fe influence cyanobacterial proliferation and toxin production. In order to monitor nutrients in aquatic ecosystems, an assay for monitoring phosphorus bioavailability to cyanobacteria was developed. The test consists of an immobilized luminescent reporter strain of Synechococcus PCC 7942, designated APL. The reporter strain harbours the gene coding the reporter protein luciferase from Vibrio harveyi under control of the inducible alkaline phosphatase promoter from Synechococcus PCC 7942, and can be induced under phosphorus limitation. The resultant CyanoSensor detects PO(3-)(4)-P in a concentration range of 0.3-8 microM after a sample incubation time of 8 h under continuous illumination (50 microE m(-2) s(-1)). The sensor also responded to a variety of organic phosphorus sources and was storable for 3 weeks at 4 degrees C. It could be demonstrated that the CyanoSensor for bioavailability monitoring is an improvement to conventional phosphorus detection methods.

Immunolocalization of the Toxin Latrunculin B within the Red Sea Sponge Negombata magnifica (Demospongiae, Latrunculiidae).

The location of latrunculin B, the major toxin of the Red Sea sponge Negombata magnifica, was revealed using specific antibodies. Antibodies from rabbits immunized with a conjugate of latrunculin B with keyhole limpet hemocyanin (KLH) were purified over a latrunculin B-Sepharose affinity column. Analysis of immunohistochemical and immunogold-stained sponge sections, using light and transmission electron microscopy, revealed latrunculin B labeling mostly beneath the sponge cortex at the border between the external (ectosome) and internal (endosome) layers (ectosome-endosome border). The endosome was less labeled than the border. Immunogold localization revealed latrunculin B in the sponge cells but not in its prokaryotic symbionts. Archeocytes and choanocytes were significantly more labeled than other cells. The antibodies primarily labeled membrane-limited vacuoles within archeocytes and choanocytes that are perhaps latrunculin B secretory or storage vesicles. Peripheral latrunculin B may have a role in defense against external epibionts, predators, and competitors.