Mid-infrared observations of young stellar objects in the vicinity of sigma Orionis

We present new mid-infrared observations of objects in the vicinity of the O-star sigma Orionis, obtained with TIMMI-2 at ESO. By constraining their near- and mid-infrared spectral energy distributions, we established the nature of previously known IRAS sources and identified new mid-infrared sources as young stellar objects with circumstellar disks, likely massive members of the sigma Ori cluster. For two of these objects we have obtained spectroscopy in the 8-13 micron range in order to investigate the chemistry of the dust grains. TX Ori exhibits a typical silicate emission feature at 10 micron, with a feature at about 11.2 micron that we identify as due to crystalline olivine. The IRAS 05358-0238 spectrum is very unusual, with a weak silicate feature and structure in the range 10-12 micron that may be explained as due to self-absorbed forsterite. We also provide the first evidence for the presence of circumstellar disks in the jet sources Haro 5-39/HH 447, V510 Ori/HH 444 and V603 Ori/HH 445.Comment: 12 pages, 13 figures, accepted for publication by A&

Inhibition of S. epidermidis adhesion to hydrogel contact lenses by anionic and nonionic surfactants

In this study the adhesion of S. epidermidis to the 4 FDA groups of hydrogel CL uncoated and coated with ½ CMC of an anionic (sodium cholate) and a non-ionic surfactant (octylglucoside) was assessed. The results revealed that cell adhesion to CL was highly dependent on surface hydrophobicity. Concerning the effect of surfactants, the non-ionic one was more effective in inhibiting microbial adhesion than the ionic surfactant. Octylglucoside promoted an inhibition in the extent of bacterial adhesion of about 62%, while sodium cholate caused a decrease in the number of cells adhered of about 43%. The effect of a commercial multipurpose care solution containing 1% of poloxamine was compared and the results indicate that adhesion inhibition was greater when 0.33% of octylglucoside was used. Octylglucoside is a natural surfactant, non-toxic, harmless to the eye, and due to its high efficiency in inhibiting microbial adhesion, as proved in this work, is recommended to be incorporated in CL care solutions

Isolation of phages from industrial environments to control biofilms

Resumo de comunicação apresentada em "16th Evergreen Phage Biology Meeting, Olympia", WA, EUA, 7-12 Agosto 2005.Biofilms are frequently in many industrial environments and are responsible for severe negative impacts such as equipment damage, loss in product quality and in economics. For instance in pulp and paper industry, microorganisms together with their exudates and the entangled fibres and filler materials form massive and slimy protusions hanging out from the material surfaces, which interfere with the paper-making process in various steps. Also, in dairy industry, biofilm presence may be responsible for pathogen cross-contamination, product defects such as package bloating, decreased shelf life, and off flavours, odours and textures. The eradication of these biofilms, as reported by several authors, is very difficult due to the nature of biofilm structure and the physiological attributes of biofilm organisms which confer an inherent resistance to biocides. The application of biological agents such as phages as an alternative to the chemical products is an interesting approach that should be studied in more detail. This work aimed the isolation of bacteria and the respective bacteriophages from a pulp and paper mill and from a dairy industry. The focus was given to EPS producing bacteria such as P. fluorescens, Sphingomonas paucimobilis, Staphylococcus sciuri, and Klebsiella oxytoca. Phages were isolated from the industrial effluents and also nearby waste water treatment plants. After phage isolation from each industrial sector, the selection was based on the wider broad of lytic activity and time of bacterial elimination. For each type of industry, a 5 phage cocktail is being developed to be tested in the control the most prevalent biofilm producing bacteria

HRM analysis targeting ITS1 and matK loci as potential DNA mini-barcodes for the authentication of Hypericum perforatum and Hypericum androsaemum in herbal infusions

Hypericum species are among the medicinal plants that are being increasingly used due to their reported health benefits. Hypericum perforatum (St. John's wort) is well known for its anti-inflammatory, antidepressive and anti-viral properties, as well as a healing agent. In Portuguese folk medicine, Hypericum androsaemum (Hiperic~ao do Ger^es) is largely used for its hepatic protective and diuretic properties. This work aimed at searching the potential use of two DNA mini-barcode candidates (ITS1 and matK) for the authentication of H. perforatum and H. androsaemum in herbal infusions. The sequencing results from ITS1 and matK regions were the basis for the development of species-specific PCR and real-time PCR assays coupled to High Resolution Melting (HRM) analysis, as simple approaches for the reliable discrimination of both species. The barcode regions were successful in the species-specific PCR identification of each target. ITS1 region revealed some intra-species variability from sequencing results, which compromises HRM analysis, while matK showed to be an adequate mini-barcode for the differentiation of both species by real-time PCR coupled to HRM analysis. The assays were effectively applied to commercial herbal infusions, enabling the consistent identification of two labels with non-declared Hypericum species.This work received financial support from the European Union (FEDER funds through COMPETE) and National Funds (FCT, Fundação para a Ciência e Tecnologia) through project EXPL/DTPSAP/ 1438/2013 (4SaferPFS e Safety of plant food supplements: searching for adulterant pharmaceutical drugs and plants) and UID/ QUI/50006/2013. Joana Costa is grateful to FCT grant (SFRH/BPD/ 102404/2014) financed by POPH-QREN (subsidised by FSE and MCTES). The authors are grateful for the supply of voucher seeds by USDA-ARS Germplasm (Beltsville, MD, USA) and by RBG (Kew, Ardingly, UK).info:eu-repo/semantics/publishedVersio

Influence of physico-chemical properties of porous microcarriers on the adhesion of an anaerobic consortium

The ability for biomass colonization of four porous mineral microcarriers (sepiolite, clay, pozzolana and foam glass- PoraverTM), was studied and related to their surface properties. The surface hydrophobicity of the mineral carriers was a more important factor influencing colonization by the anaerobic consortium than was surface charge. It was possible to correlate linearly the degree of hydrophobicity with the biomass retention capacity. Although the thermodynamic theory did not explain adhesion, an increase in cell attachment was directly related to the decrease of the positive values of the free energy of adhesion. Surface roughness, porosity and the amount of surface Mg²+, were also determinant factors in bacterial immobilization. However a great biomass accumulation can originate a decrease in biological activity due to mass transfer limitations

Real-time quantification of Pseudomonas fluorescens cell removal from glass surfaces due to bacteriophage FS1 application

Aims: To study the efficacy of the lytic phage φS1 in eliminating Pseudomonas fluorescens in the early stage of biofilm formation, using an in situ and real time methodology for cell quantification. Methods and Results: Cell adhesion and phage infection studies were carried out in a parallel plate flow chamber under laminar conditions. Cells were allowed to adhere until reaching 1·7–1·8 × 106 cells cm−2 and phage infection was performed with two different phage concentrations (2 × 109 PFU ml−1 and 1 × 1010 PFU ml−1). Phage concentration clearly affects the speed of infection. The less concentrated phage solution promoted a three times slower rate of cell removal but did not affect the overall percentage of cell removal. In fact, after a longer infection period the less concentrated phage solution reached the same 93% cell removal value. Conclusions: Phages are efficient in the eradication of bacterial cells at the early stage of biofilm formation and their presence at the surface did not allow bacterial recolonization of the surface. Significance and Impact of the Study: To date, no published studies have been made concerning in situ and real time quantification of cell removal from surfaces due to phage action.Fundação para a Ciência e a Tecnologia (FCT

Comparison of the extracellular polymeric substances of Candida albicans and Candida dubliniensis biofilms

Candida albicans and Candida dubliniensis live as benign commensal organisms in the oral cavity of both healthy and unhealthy individuals behaving, under certain conditions, as opportunistic pathogens, causing candidiasis. These two Candida species have been mismatched for years, but recently Candida dubliniensis was recovered from the mouth of imunnosupressed patients and identified as a different species. Candidiasis is usually related with the Candida capacity of forming biofilms on inert or biological surfaces, being this phenotype associated with infections. Biofilms are complex structures of microbial communities attached to a surface, in which microorganisms are embedded in a matrix of extracellular polymeric substances (EPS), composed mainly by proteins and polysaccharides. The biofilm matrix holds the potential of determining possible mechanisms of resistance of Candida biofilms. Several factors are known as affecting the production of EPS, namely, growth medium, growth phase and substratum. This study focused the influence of artificial saliva growth medium in the composition of EPS of biofilms formed by both Candida albicans and Candida dubliniensis strains. Biofilms of one strain of Candida albicans and two strains of Candida dubliniensis were formed in an artificial saliva growth medium (ASGM) and compared with those formed in Sabouraud Dextrose Broth (SDB) and analysed after 48h.The differences between the EPS of biofilms were evaluated (after sonication) in terms of proteins (quantified using the BCA protein assay kit) and polysaccharides (quantified using the phenol-sulphuric method). Proteins were also analysed by SDS-PAGE. In SDB the amount of proteins and polysaccharides in the EPS of biofilms formed by Candida albicans was lower than in the EPS of biofilms formed by Candida dubliniensis strains. In the presence of ASGM the amount of proteins and polysaccharides was similar among the EPS of biofilms of Candida albicans and one of the Candida dubliniensis strains and was lower in biofilms of Candida albicans than in biofilms of the other Candida dubliniensis. Analysis of protein profiles obtained by SDS-PAGE showed that all strains present similar patterns independently of the medium of biofilm formation. Biofilms formed in ASGM originated different amounts of EPS, either in terms of polysaccharides or proteins, compared to the ones formed in SDB. Differences were also found in the profile of extracellular proteins of each strain, depending on the medium