Poly-N-acetyl glucosamine expression in Staphylococcus epidermidis biofilm cells affects the immune response and promotes tissue pathology in infected hosts

Staphylococcus epidermidis is a biofilm - forming bacterium and a leading etiological agent of nosocomial infections. The ability to establish biofilms on indwelling medical devices is a key virulence factor for this bacterium. Still, the influence of poly - N - acetyl glucosamine (PNAG), the major component of the extracellular biofilm matrix, in the host immune response has been scarcely studied. Here, t h is influence was assessed in mice challenged i.p. with PNAG - p roducing (WT) and isogenic - mutant lacking PNAG (M10) bacteria grown in biofilm - inducing conditions. Faster bacterial clearance was observed in the mice infected with WT bacteria than in M10 - infected counterparts , which w as accompanied by earlier neutrophil recruitment and higher IL - 6 production. Interestingly, in the WT - infected mice, but not in those infected with M10 , elevated serum IL - 10 was detected . To further study the effe ct of PNAG in the immune response, mice were primed with WT or M10 biofilm bacteria and subsequently infected with WT biofilm - released cells. WT - primed mice presented a higher frequency of splenic IFN - γ + and IL - 17 + CD4 + T cells, and more severe liver patho logy than M10 - primed counterparts. Nevertheless, T reg cells obtained from the WT - primed mice presented a higher suppressive function than those obtained from M10 - primed mice. This effect was abrogated when IL - 10 - deficient mice were similarly primed and infected indicating that PNAG promotes the differentiati on of highly suppressive T reg cells by a mechanism dependent on IL - 10. Altogether, these results provide evidence help ing explain ing the coexistence of inflammation and bacterial persistence often observed in biofilm - originated S. epidermidis infections

Ex situ collection of Limonium spp.: cytogenetic and reproductive characterization for the conservation of rare species

Dissertação mestrado em Biologia Molecular, Biotecnologia e Bioempreendedorismo em Plantas

The isolation of Aspergillus spp from harvested maize in three Portuguese regions

In Portugal, maize is the cereal that involves more agriculture explorations. Aspergillus spp., among other species, are usually associated with this cereal, during drying and storage, making this commodity susceptible to mycotoxins (such as aflatoxins, ochratoxins, and cyclopiazonic acid). The aim of this study was to evaluate the mycotoxigenic potential of isolated Aspergillus strains from these maize samples and correlate it with the sampling place, the weather conditions, and local practices during drying and storage. The samples were collected between November 2008 and April 2009 in maize association of producers facilities in Coimbra, Santarém and Portalegre. The isolated strains were divided in three distinct groups, Aspergillus section Flavi, Aspergillus section Nigri and others Aspergillus. The preliminary results show that there are differences between the incidence of these groups in the three sampling places, especially in Coimbra, probably due to a lower mean temperatures and higher humidity levels. These data will be presented and discussed.

Compositional analysis of biofilms formed by Staphylococcus aureus isolated from food sources

The Supplementary Material for this article can be found online at: http://journal.frontiersin.org/article/10.3389/fmicb. 2016.00390

Determination of the importance of iron acquisition for Staphylococcus epidermidis biofilm survival in human blood

Dissertação de mestrado em Bioengenharia

Characterization of microbial populations in a wastewater treatment plant focusing on Staphylococcus aureus and Pseudomonas aeruginosa

Dissertação de mestrado em Bioengenharia