Hyperhalophilic archaeal biofilms: growth kinetics, structure and antagonic interaction in continuous culture

Biofilms by the hyperhalophilic archaea Halorubrum sp. and Halobacterium sp. were analyzed, and for the first time the progression of structural features and the developmental parameters of these sessile populations are described. Optical slicing and digital analysis of sequential micrographs showed that their three dimensional structure was microorganism dependent. Biofilms of Halobacterium sp. developed in clusters that covered about 30% of the supporting surface at the interface level and expanded over about 86 ± 4 μm in thickness, while Halorubrum sp. biofilms covered less than 20% of the surface and reached a thickness of 41 ± 1 μm. The kinetics of growth was lower in biofilms, with generation times of 27 ± 1 and 36 ± 2 h for Halobacterium sp. and Halorubrum sp., respectively, as compared to 8.4 ± 0.3 and 14 ± 1 h in planktonic cultures. Differences between microorganisms were also observed at the cell morphology level. The interaction between the two microorganisms was also evaluated, showing that Halobacterium sp. can outcompete already established Halorubrum sp. biofilms by a mechanism that might include the combined action of tunnelling swimmers and antimicrobial compounds.Fil: Di Meglio, Leonardo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Biológicas; ArgentinaFil: Busalmen, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); ArgentinaFil: Pastore, Juan Ignacio. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: Ballarin, Virginia Laura. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: Nercessian, Debora. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Biológicas; Argentin

Prevalence of measles virus-specific IgG antibodies according to vaccination schedule in medical students of Padua University.

Aims: The goal of the present study was to establish the efficacy of the measles vaccine and the validity of the vaccination schedule adopted in Italy. Materials & methods: The following procedures are adopted: analyze the compliance to the vaccination schedule; assess the seroprevalence of measles antibodies according to the year of birth and the number of doses; and investigate the persistence of positive antibodies post-vaccination. We gathered and elaborated data of both vaccination history and seroprevalence against measles in a large population of students (4195) belonging to the Medical School of Padua University (Italy). Results: Our results reveal a requirement for a two-dose vaccination schedule to ensure protection from the disease. Nevertheless, these results clearly indicate that the percentage of seropositivity reached using the two-dose strategy is below the percentage (95%) that ensures optimal population immunity. Conclusion: It is uncertain whether immune coverage persists when circulating antibodies vanish, but two vaccine doses should prevent disease outbreaks