Glutaraldehyde exposed Pseudomonas fluorescens: a case of biofilm persistence?

From the assessment of the recovery capability of pseudomonas fluorescens atcc 13525t after exposure to several glutaraldehyde (gta) concentrations (100, 200 and 400 mg/l) and exposure times (1 and 2 hours), it was found that, for gta concentrations above 100 mg/l, whatever the exposure time, bacterial cells presented different growth patterns in solid media. after this statement, the recovered cells were initially characterized using api ne20 strips and species identification was obtained using the api database. the type culture and the cells obtained after treatment with concentrations below 200 mg/l were identified as p. fluorescens. conversely, the identification of cells exposed to higher concentrations of gta failed. the electrophoretic profiles of both the type culture and the cells exposed to gta were obtained by pcr, using the primer t3b. the results showed identical profiles for the type culture and the cells exposed to low gta concentrations, and a totally different pattern for cells exposed to gta concentrations above 200 mg/l. sequencing of the 16s rdna gene is under way in order to further clarify the differences observed. the p. fluorescens atcc 13525 (used as control) and the cells treated with 200 mg/l of gta during 2 hours were selected for further studies. a comparative study was carried out between the above referred cells in terms of morphological structure, surface properties, respiratory activity, biofilm formation ability and susceptibility to gta. the results showed that the cells treated with 200 mg/l of gta presented an elongated structure, were about 30 times less active in terms of respiratory activity and were more hydrophilic. concerning biofilm formation, both tested cells presented biofilm formation ability, but the gta treated cells produced about 2 times more mass of biofilm. however, this biofilm had a specific respiratory activity 3 times less than the one formed by the control culture. the biofilm behaviour immediately after exposure to 200 mg/l of gta during 2 hours, was similar for both situations studied, since a low biofilm removal and inactivation was achieved. however, 7 hours after gta exposure, only 55% of the biofilm formed by the control culture remained attached to the surface, while for the biofilms formed by the treated cells all the deposit remained attached to the surface. the results obtained in this work indicate that cells submitted to gta treatment may give rise to biofilms harder to remove and consequently more persistent, than non-treated cells. therefore, care must be taken in the selection and application of biocides in industrial biofilms

Phytotoxicity of alkaloids, coumarins and flavonoids isolated from 11 species belonging to the Rutaceae and Meliaceae families

Meliaceae and Rutaceae families are known for the high diversity of their secondary metabolites, which include many groups that represent a rich source of structural diversity, and are good candidates as sources of allelochemicals that could be useful in agriculture. In the work described here the bioactivity profiles were evaluated for 3 alkaloids (1–3), 12 coumarins (4–15), 2 phenylpropanoic acid derivatives (16 and 17) and 14 flavonoids (18–31) from 11 species belonging to the Meliaceae and Rutaceae families. All compounds were tested in the wheat coleoptile bioassay and those that showed the highest activities were tested on the STS (Standard Target Species) Lepidium sativum (cress), Lactuca sativa (lettuce), Lycopersicon esculentum (tomato), and Allium cepa (onion). Most of the isolated compounds showed phytotoxic activity and graveoline (3), psoralen (8), and flavone (18) were the most active, with bioactivity levels similar to that of the commercial herbicide Logran1. The results indicate that these compounds could be involved as semiochemicals in the allelopathic interactions of these plant species

Exploitation of new chalcones and 4H-chromenes as agents for cancer treatment

Chalcone and chromene derivatives were synthesized in good yield through simple and effective reactions using innocuous solvents such as water and ethanol and high yielding aldol condensations. Generally, the reactions were performed at room temperature, leading to the isolation of highly pure compounds. These compounds were tested on breast cancer cells (MCF-7 and Hs578T) and breast non-neoplastic cells (MCF-10A). After determination of IC50 value, specific assays were performed to analyze the potential of these compounds, and those bearing halogenated substituents presented enhanced activity comparing to methoxyl or methyl groups. More specifically, the bromine atom was often present in the bioactive molecules that proceeded to the final assays and showed to be promising candidates for further studies. The selected chromene acted as a cell migration inhibitory agent and triggered regulated cell death associated with G2/M cell-arrest and microtubule destabilization. For chalcones, the results suggest an anti-proliferative activity. Also, results for combination-therapy potentiated the antitumor effect of doxorubicin and reduced cytotoxicity in MCF-10A cells.We acknowledge the financial support from University of Minho, Fundaçao para a Ci ~ encia e a Tecnologia and FEDER- ^ COMPETE for financial support through Centro de Química (UID/ QUI/00686/2013 and UID/QUI/0686/2016), and for the postdoctoral grants awarded to Marta Costa (SFRH/BPD/79609/2011) and Belem Sampaio-Marques (SFRH/BPD/90533/2012), PhD grants of Filipa Santos (SFRH/BD/87139/2012) and Olívia Pontes (SFRH/BD/128850/ 2017). The confocal microscope Olympus FV1000 acquired under the financial support of PPBI-POCI-01-0145-FEDER-022122. The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network (RNRMN) and was purchased within the framework of the National Program for Scientific Re-equipment, contract REDE/1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT. This work was also developed under the project NORTE-01-0145- FEDER-000013, by the Northern Portugal Regional Operational Program (NORTE 2020), through the European Regional Development Fund (FEDER) and the Competitiveness Factors Operational Program (COMPETE) and by National funds, through the Foundation for Science and Technology (ref. POCI-01-0145-FEDER007038)