Data on the adhesion of biofilms formed by Pseudomonas fiuorescens to aluminium, copper and brass surfaces are reported in this paper. Biofilm thicknesses after 48 h were lower on the brass plates than on the other two metals. The results are compared with predictions of bacterial adhesion obtained by the method of van O ss et al. (C.J. van Oss, M.K. Chaudhury and R.J. Good, Chern. Rev ., 88 (1988) 927), based on the evaluation of the change in the free energy of adhesion of the interacting systems. The presence of metallic ions released by the surfaces into the environment seemed to affect bacterial metabolism and adhesion and were taken into account to explain the discrepancies between experimental data and thermodynamic predictions. The possible effects of the extracellular polymers excreted by the bacteria on their attachment abilities are also stressed.

Conductive nanomaterials affect anaerobic digestion (AD) processes usually by improving methane production. Nevertheless, their effect on anaerobic communities, and particularly on specific trophic groups such as syntrophic bacteria or methanogens, is not extensively reported. In this work, we evaluate the effect of multi-walled carbon nanotubes (MWCNT) on the activity of two different anaerobic microbial communities: an anaerobic sludge and a river sediment. Methane production by anaerobic sludge was assessed in the presence of different MWCNT concentrations, with direct methanogenic substrates (acetate, hydrogen) and with typical syntrophic substrates (ethanol, butyrate). MWCNT accelerated the initial specific methane production rate (SMPR) from all compounds, with a more pronounced effect on the assays with acetate and butyrate, i.e., 2.1 and 2.6 times, respectively. In the incubations with hydrogen and ethanol, SMPR increased 1.1 and 1.2 times. Experiments with the river sediment were performed in the presence of MWCNT and MWCNT impregnated with 2% iron (MWCNT-Fe). Cumulative methane production was 10.2 and 4.5 times higher in the assays with MWCNT-Fe and MWCNT, respectively, than in the assays without MWCNT. This shows the high potential of MWCNT toward bioenergy production, in waste/wastewater treatment or ex situ bioremediation in anaerobic digesters.

No abstract

Biosorbent materials are effective in the removal of spilled oil from water, but their effect on hydrocarbonoclastic bacteria is not known. Here, we show that corksorb, a cork-based biosorbent, enhances growth and alkane degradation by Rhodococcus opacus B4 (Ro) and Alcanivorax borkumensis SK2 (Ab). Ro and Ab degraded 96 ± 1% and 72 ± 2%, respectively, of a mixture of n-alkanes (2 g L–1) in the presence of corksorb. These values represent an increase of 6 and 24%, respectively, relative to the assays without corksorb. The biosorbent also increased the growth of Ab by 51%. However, no significant changes were detected in the expression of genes involved in alkane uptake and degradation in the presence of corksorb relative to the control without the biosorbent. Nevertheless, transcriptomics analysis revealed an increased expression of rRNA and tRNA coding genes, which confirms the higher metabolic activity of Ab in the presence of corksorb. The effect of corksorb is not related to the release of soluble stimulating compounds, but rather to the presence of the biosorbent, which was shown to be essential. Indeed, scanning electron microscopy images and downregulation of pili formation coding genes, which are involved in cell mobility, suggest that cell attachment on corksorb is a determinant for the improved activity. Furthermore, the existence of native alkane-degrading bacteria in corksorb was revealed, which may assist in situ bioremediation. Hence, the use of corksorb in marine oil spills may induce a combined effect of sorption and stimulated biodegradation, with high potential for enhancing in situ bioremediation processes.

A Síndrome respiratória obstrutiva dos braquicéfalos (SROB) é caracterizada por alterações anatômicas e fisiológicas que provocam importante obstrução das vias aéreas superiores e afetam predominantemente cães de raças braquicéfalicas. Essas alterações anatômicas podem ser classificadas em primárias, como a estenose de narina, prolongamento de palato mole e hipoplasia de traqueia, e secundárias, geralmente ocasionadas pelo aumento da turbulência e resistência ao ar, como a eversão de sáculos laríngeos, edema, inflamação da nasofaringe, paralisia e colapso de laringe. Pode ocorrer a evolução dessas alterações com a idade, desenvolvendo doenças respiratórias mais graves e até levar o paciente a óbito. O objetivo deste relato foi descrever um caso clínico cirúrgico de um canino, da raça bulldogue francês, submetido às técnicas de rinoplastia e estafilectomia. O paciente deu entrada com um quadro de dificuldade respiratória quando submetido à exercício, com dispneia, roncos durante o sono, inquietação e algumas vezes regurgitava o alimento. Ao exame físico, constatou-se ser a Síndrome braquicefálica, em que apresentava estenose de narina e estridor inspiratório, sugerindo prolongamento de palato mole. O paciente foi encaminhado para cirurgia corretiva de Rinoplastia e estafilectomia. O procedimento foi realizado, com um bom prognóstico e melhora significativa na qualidade de vida.