Kinetics of action of Schiff bases on Aerobacter aerogenes as studied by microcalorimetry

A series of chitosans with various molecular weights from 1.2 ϫ 10 3 to 30.0 ϫ 10 4 were prepared by oxidative degradation with H 2 O 2 and characterized by IR, 13 C-NMR, and gel permeation chromatography. Their carboxylic contents increased with a decrease in molecular weight (M w ). The moisture-absorption and moisture-retention capacities of resulting chitosans were dependent on both the molecular weight and the degree of deacetylation (DD). Microcalorimetry was first used to study the kinetics of action of the chitosans on a strain of Staphylococcus aureus at pH 7. The antibacterial activity of the water-soluble chitosan against S. aureus, Escherichia coli, and Salmonella typhi was evaluated by the conventional agar plate method at pH 7. The water-soluble product with M w of 0.45 ϫ 10 4 from initial chitosan of DD of 90% showed high moisture-absorption and moisture-retention capacities, and Ͻ2% concentration can completely inhibit the growth of these bacteria.

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“…The voltage signal was recorded by an LKB‐2210 recorder. The method was used in this experiment as previously described 17…”

Section: Methodsmentioning

confidence: 99%

Moisture retention and antibacterial activity of modified chitosan by hydrogen peroxide

Qin

Xiao

et al. 2002

J of Applied Polymer Sci

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Bioremediation of chromate: thermodynamic analysis of the effects of Cr(VI) on sulfate-reducing bacteria

Chardin

Dolla

Chaspoul

et al. 2002

Applied Microbiology and Biotechnology

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Developing new bioremediation processes for soils and effluents polluted by Cr(VI) requires the selection of the most efficient and the most heavy-metal-resistant bacteria. The effects of Cr(VI) on bioenergetic metabolism in two sulfate-reducing bacteria (SRB), Desulfovibrio vulgaris Hildenborough and Desulfomicrobium norvegicum, were monitored using isothermal microcalorimetry. The complete reduction of Cr(VI) to Cr(III) was studied by spectrophotometry and by speciation using a combination of high-performance liquid chromatography and inductively coupled plasma-mass spectrometry. Results revealed that Cr(VI) induces an inhibition of growth with concomitant production of energy, which can be compared to the reaction of the bacteria to a stress such as oxidative stress. Moreover, the sensitivity of bacteria towards this metal is as a characteristic of the strain, which leads to differences in the kinetics of Cr(VI) reduction. The study by microcalorimetry of heavy metal effects on SRB bioenergetic metabolism thus appears an appropriate tool to identify better strains to be used for industrial bioremediation process development.

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Oxidation of melatonin on a glassy carbon electrode modified with metallic glucosamines. Synthesis and characterization

Antoni

Lillo

Valenzuela

et al. 2016

J Solid State Electrochem

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In this study, a glassy carbon electrode modified with different cobalt glucosamines (CoGlu-R), iron glucosamines (FeGlu-R), and nickel glucosamines (NiGlu-R) was used for the electroanalytical determination of melatonin in buffer solutions at pH 7.3 using cyclic and square wave voltammetry. The complexes were synthesized and characterized by IR-TF, H-1-NMR, and UV-visible spectroscopy. When comparing glucosamines of different metals, the influence of the nature of the metal on the activity is not very strong. The most active complex was CoGlit-R. The oxidation peak was used to determine melatonin in the concentration range of 10(-8)-10(-5) M with a detection limit of 2.15 x 10(-7) M (LOD). Our results indicate that the current peak is under mass transport control and probably suggest that chemical reactions coupled with electrochemical steps are involved. The melatonin oxidation current with this kind of modified electrodes is small but this modified electrode shows high selectivity in medium-199 (glutamine, phenol red, glucose, Na+, CO32-) with human placental tissue; trophoblast and endothelial cells (K+, Ca2+, traces of Cu2+ and Mg2+), yet the tryptophan causes interference.FONDECYT 1120164 Direccion de Investigation de la Universidad del Bio-Bio DIUBB 142209 4/

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Kinetics of action of Schiff bases on Aerobacter aerogenes as studied by microcalorimetry

Cited by 14 publications

References 7 publications

Moisture retention and antibacterial activity of modified chitosan by hydrogen peroxide

Moisture retention and antibacterial activity of modified chitosan by hydrogen peroxide

Bioremediation of chromate: thermodynamic analysis of the effects of Cr(VI) on sulfate-reducing bacteria

Oxidation of melatonin on a glassy carbon electrode modified with metallic glucosamines. Synthesis and characterization

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