Films of chitosan and chitosan-oligosaccharide neutralized and thermally treated: Effects on its antibacterial and other activities

The present study focuses on the effects of heat and neutralization treatments on solubility, water vapour permeability and antimicrobial activity of chitosan (Ch) and chitosan/chitooligosaccharide (ChO)-based films. ChO films showed stronger antimicrobial activity against Escherichia coli, Bacillus cereus, Staphylococcus aureus, Serratia liquefaciens and Lactobacillus plantarum than Ch films, indicating that this effect is attributed to the presence of chitooligosaccharides (COS) in the films. Heat and neutralization treatments decreased significantly the solubility of chitosan films and gave rise to a sharp loss in their antimicrobial activity. The incorporation of COS in chitosan films increased the inhibitory effect against the studied microorganisms without affecting significantly the water vapour permeability of the films. Thus, it is possible to get a more insoluble chitosan film with high antimicrobial activity by means of incorporation of COS combined with heat or neutralization treatments.MINECO, project (MAT2010-21621-C02-01

Obtención de hidrogeles derivados del ácido itacónico

Se presenta una técnica para la obtención de hidrogeles de acrilamida, empleando comonámeros monoésteres del ácido itacántco. A estos hidrogeles se les determina su cinética de hinchamiento a pH neutro y 20°C

Efficient P(3HB) extraction from Burkholderia sacchari cells using non-chlorinated solvents

A technique using safer, non-chlorinated organic solvents for the extraction of poly-3-hydroxybutyrate (P(3HB)) from bacterial cells was developed, aiming to attain high recovery yields and purities. Some solvents were selected from the GlaxoSmithKline guide as sustainable industrial solvents and the solubility of P(3HB) calculated using predictive equations from literature. Based on the calculated solubility values, anisole, cyclohexanone and phenetole were tested as extraction solvents and the relevant process variables (extraction temperature, extraction time and mass of cells/solvent volume ratio) were addressed. Polymer recovery yields of 97% and 93% were obtained with anisole and cyclohexanone, respectively, at 120–130 °C using a cell/solvent ratio of 1.5% (w/v). Maximum polymer purities using these experimental conditions were 98% for both solvents. The recovery yield and the polymer purity attained with chloroform (reference solvent) were 96 and 98%, respectively. Higher cell/solvent ratios of 6.0% (w/v) showed slightly lower recovery yields and purities. The average molecular weight and the thermal properties of the polymers extracted with the alternative solvents were fully comparable to those of the polymers obtained by chloroform extraction, demonstrating that the applied conditions did not significantly alter the properties of the extracted P(3HB).European Commission´s FP