Breakfast at CEB

14th June 2010 at 9.30H, DEB/CEB Amphitheatre

Joana Bento, Mechanisms involved in helper phage-mediated derepression of Staphylococcus aureus superantigen pathogenicity islands

1st year student

Staphylococcus aureus is a major human bacterial pathogen, of special concern due to the high prevalence of methicillin resistant strains (MRSA). S. aureus has a large array of virulence factors, which are commonly found in association with gene clusters known as pathogenicity islands (SaPIs). Toxin-carrying SaPIs can be transferred among staphylococcal strains by interacting with helper bacteriophages. The molecular mechanisms of helper phage mobilization of the SaPIs are not well known. In the proposed workplan, the helper phage sri gene and the SaPI1 stl gene, two genes recently implicated in SaPI1 derepression, will be further characterized. The interaction of these two proteins and the subsequent effects on DNA binding will be studied in detail. The role of an additional putative SaPI1 transcriptional regulator, Str, will also be investigated. DNA binding studies will locate the target of this regulator, and effects on transcription will be determined by measuring mRNA.

Maria Ines Matos, Troubleshooting of filamentous bulking using hybrid systems

2nd year student

Activated sludge systems frequently face filamentous bulking – a term used to describe the overgrowth of filamentous microorganisms (bacteria and/or fungi) – that is very difficult to control. Several approaches have been used to reduce this common problem. For instance, the compartmentalisation of the aeration tank or its conversion to a batch process have been used to increase sludge settleability and compaction. Although these approches have been successful and have reduced filamentous bulking in many activated sludge systems, there are some reports that point out to their failure. An alternative to the existing technologies for filamentous bulking control might be the incorporation of a support material for biofilm growth into suspended growth reactors. Interestingly, no problems with excessive growth of filamentous microorganisms have been reported in the cases where activated sludge processes were combined with biofilm growth, but this line of research wasn’t continued. The aim of this work is then to study how systems combining suspended biomass with biofilm growth control filamentous bulking.

Vera Carvalho, Dextrin nanoparticles as a protein delivery system: the interleukin-10 case study

3rd year student

Interleukin-10 (IL-10) is an anti-inflammatory cytokine, which active form is a non-covalent homodimer with two intramolecular disulphide bonds that are essential to its biological activity. A mutated form of murine IL-10 was successfully expressed in E. coli, recovered and purified from inclusion bodies. Its ability to reduce tumor necrosis factor a synthesis and down-regulate class II major histocompatibility complex molecules expression on endotoxin-stimulated bone marrow-derived macrophages was confirmed, and shown to be similar to a commercially available IL-10. Due to IL-10 potential applications in various medical fields, it is essential to develop systems that can effectively deliver the protein. For this purpose, dextrin nanoparticles have been used and this work shows that dextrin nanoparticles effectively incorporate IL-10 and enable the slow release of biologically active IL-10 over time. Altogether, these results demonstrate the suitability of dextrin nanoparticles to be used as a system for the controlled release of IL-10.