Influence of the uronic acid composition on the gastroprotective activity of alginates from three different genus of Tunisian brown algae.

Alginates from three genus of Tunisian brown algae were isolated and characterized by size exclusion chromatography and Solid-state NMR spectroscopy. Alginate from Padina pavonica (APP) had the highest molecular weight (Mw) with 147,000g/mol while it was 85,000g/mol for alginate from Cystoseira compressa (ACC) and 58,000g/mol for alginate from Dictyopteris membranaceae (ADM). The mannuronate (M) to guluronate (G) ratios were estimated from spectral deconvolution of the C CP/MAS spectra and the results has shown that all the extracts are mannuronic acid-rich alginates with M/G ratio increased in the order ADM - ACC - APP.

Influence of freezing stress on morphological alteration and biofilm formation by Listeria monocytogenes: relationship with cell surface hydrophobicity and membrane fluidity.

The morphological changes and adhesive property of three Listeria monocytogenes strains submitted to freezing stress (-20 °C) were studied. The atomic force micrographs showed a reduction in the cell size and an evolution to coccoid shape. The phenotypic slime production of L.