Differences in biofilm formation between Scenedesmus obliquus and Chlorella vulgaris were examined, as well as the effects of substrate properties. Species selection and species control had significant effects. In non-sterile conditions, C. vulgaris shifted from planktonic (23.7% attachment) to sessile (79.8% attachment) growth, and formed films of higher average thickness (52 ± 19 µm) than in sterile conditions (7 ± 6 µm). By contrast, S. obliquus attained similar thicknesses (54 ± 31 µm and 53 ± 38 µm) in both sterile and non-sterile conditions. The effect of substrate properties was minimal. Both species grew films of similar thickness (~ 30 µm for S. obliquus, <10 µm for C. vulgaris) on materials ranging from hydrophilic (glass) to hydrophobic (polytetrafluoroethylene). Micropatterning the surface also had little effect on film formation. The results indicate that species selection and species control are more important that substrate properties in the development of microalgal biofilms.

Differences in biofilm formation between Scenedesmus obliquus and Chlorella vulgaris were examined, as well as the effects of substrate properties. Species selection and species control had significant effects. In non-sterile conditions, C. vulgaris shifted from planktonic (23.7% attachment) to sessile (79.8% attachment) growth, and formed films of higher average thickness (52 ± 19 µm) than in sterile conditions (7 ± 6 µm). By contrast, S. obliquus attained similar thicknesses (54 ± 31 µm and 53 ± 38 µm) in both sterile and non-sterile conditions. The effect of substrate properties was minimal. Both species grew films of similar thickness (~ 30 µm for S. obliquus, <10 µm for C. vulgaris) on materials ranging from hydrophilic (glass) to hydrophobic (polytetrafluoroethylene). Micropatterning the surface also had little effect on film formation. The results indicate that species selection and species control are more important that substrate properties in the development of microalgal biofilms.

This study examines the effects of Pseudomonas aeruginosa (PAO1) biofilm, with a concentration of cells similar to that reported for saturated aquifers, on the transport of poly(acrylic acid) stabilized nanoscale zero valent iron (pnZVI) in 14 cm long, saturated, laboratory packed columns, with ionic strengths (ISs) of 1 and 25 mmol NaCl. With biofilm, the retention of pnZVI increased with higher solution IS, while IS played no role in the retention of nanoparticles without biofilm. However, the Tufenkji-Elimelech correlation equation predicts 5% less pnZVI collisions in biofilm coated columns due to a sixfold reduction of the Hamaker constant. Also, DLVO energy considerations predict the most favorable attachment for uncoated porous media at the higher IS. Reasons for the disagreement between theory and experiment are shown to be due to the non-ideality of the biofilm system. This research indicates that current laboratory studies underestimate nanoparticle transport distances in the subsurface. / Environmental Science

Techn. Universiẗat, Diss., 2007--Darmstadt.

Univ., Diss., 2009--Kassel.

Hannover, Universiẗat, Diss., 2004.

Techn. Universiẗat, Diss., 2004--Berlin.

University, Diss., 2004--Osnabrück.

Essen, Universiẗat, Diss., 2005--Duisburg.

Made available in DSpace on 2014-12-02T11:16:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-11-14Bitstream added on 2014-12-02T11:21:06Z : No. of bitstreams: 1 000792872.pdf: 571447 bytes, checksum: 3bae358d477e471a159de61135729477 (MD5) / Este estudo avaliou a atividade antimicrobiana de um reembasador resiliente Coe Soft® (RRCS) combinado ao polímero antimicrobiano poli (2 tert-butilaminoetil) metacrilato (PTBAEMA) sobre formação de biofilme de Staphyloccocus aureus, Streptococcus mutans e Candida albicans. Espécimes circulares (15mm x 3mm) do RRCS foram confeccionados (n=27), esterilizados, divididos em três grupos de acordo com as concentrações de PTBAEMA a 0% (controle), 10% e 25% e individualmente inoculados em tubos de falcon contendo 5mL de caldo RPMI para os fungos, TSB para S. aureus e BHI para S. mutans e mantidos em overnight a 37ºC em incubadora com agitação orbital a 75rpm, sendo o S. mutans em microaerofilia. Após a inoculação dos espécimes seguiu-se a formação e maturação do biofilme a 37ºC sob agitação orbital a 75rpm. Em seguida cada espécime foi transferido para tubos contendo PBS e diluições seriadas foram realizadas. Alíquotas dessas diluições foram semeadas em placas de Petri e incubadas a 37ºC por 48h. Os dados obtidos foram transformados em log (UFC+1)/mL, considerando-se α=0,05. Os resultados demonstraram que o grupo contendo 25% de PTBAEMA inibiu completamente a formação de biofilme de S. aureus e S. mutans. Uma redução significativa na contagem de S. aureus e S. mutans (Kruskal- Wallis e Dunn; p=0,001) para o grupo contendo 10% de PTBAEMA foi observada quando comparada aos valores encontrados nos respectivos grupos controle. Para C. albicans não foi encontrada diferença significante entre grupos contendo PTBAEMA e o grupo controle (ANOVA; p>0,05). Conclui-se que os RRCS contendo 10% e 25% de PTBAEMA inibiram a formação de biofilme de S. aureus e S. mutans. Entretanto não teve efeito significante na formação de biofilme de C. albicans. / This study evaluated the antimicrobial activity of the resilient reliner Coe Soft ® (RRCS) combined with antimicrobial polymer poly (2-tert butylaminoethyl) methacrylate (PTBAEMA) on Staphylococcus aureus, Streptococcus mutans and Candida albicans biofilm formation. RRCS circular specimens were prepared (n=27), sterilized, divided into three groups according to PTBAEMA concentrations of 0% (control), 10% and 25% and inoculated into individual falcon tubes containing 5 mL of RPMI broth for fungi, TSB for S. aureus and BHI for S. mutans and kept overnight at 37°C with orbital shaking incubator at 75rpm, and S. mutans in microaerophilic. The specimens’ inoculations were followed by biofilm formation and its maturation at 37°C under orbital shaking at 75rpm. After that, each sample was transferred to tubes containing PBS and serial dilutions were performed. Aliquots of these dilutions were plated in Petri dishes and incubated at 37°C for 48h. The data were transformed into log (CFU +1)/mL, considering α = 0.05. The results showed that the group containing 25% of PTBAEMA inhibited completely biofilm formation of S. aureus and S. mutans. A significant reduction in counts of S. aureus and S. mutans (Kruskal- Wallis and Dunn; p = 0.001) were found in group containing 10% of PTBAEMA when compared to the values in the corresponding control groups. C. albicans had no significant differences between groups containing PTBAEMA and the control group (ANOVA; p> 0.05). It is concluded that the RRCS containing 10% and 25% PTBAEMA inhibited the biofilmformation of S. aureus and S. mutans. However, no significant effect was found on C. albicans biofilm formation.