Functionalization of chitosan by laccase-catalyzed oxidation of ferulic acid and ethyl ferulate under heterogeneous reaction conditions.

Chitosan particles were functionalized with ferulic acid (FA) and ethyl ferulate (EF) as substrates using laccase from Myceliophtora thermophyla as biocatalyst. The reactions were performed with chitosan particles under an eco-friendly procedure, in a heterogeneous system at 30°C, in phosphate buffer (50mM, pH 7.5). The FA-chitosan derivative presented an intense yellow-orange color stable while the EF-chitosan derivative was colorless. The spectroscopic analyses indicated that the reaction products bound covalently to the free amino groups of chitosan exhibiting a novel absorbance band in the UV/Vis spectra between 300 and 350nm, at C-2 region by the duplication of C-2 signal in the 13C NMR spectrum, via Schiff base bond (NC) exhibiting novel bands in the FT-IR spectrum at 1640 and 1620cm-1. Additionally, antioxidant capacities of chitosan derivatives showed that the chitosan derivatives presented improved antioxidant properties, especially for FA-chitosan derivative (EC50 were 0.52±0.04, 0.20±0.02mg/ml for DPPH and ABTS+ scavenging, respectively).

Correlation between the release of sugars and uronic acid and free oil recovery following enzymatic digestion of oil seed cell walls.

Aqueous extraction of sunflower seeds and rapeseeds with mixtures of hydrolytic enzymes were carried out in 2-L reactor and uronic acid and reducing sugar concentrations were measured during digestion. The goal of the study was to determine if a correlation between those concentrations and free oil exists that would allow predicting free oil release from aqueous solution measurements. Similar concentrations of 4.5 and 4.7 g/L of reducing sugars and 43 and 55 g/L of uronic acid were found for sunflower and rapeseeds, respectively. The corresponding yields of free oil from the two seeds were 83% and 16% of total oil, and this difference was due to the formation of an emulsion in the rapeseed dispersion. Therefore, measurement of reducing sugars or uronic acid concentrations are not sufficient to predict a release of free oil from all oil seeds.

Exoskeletal deformities in Palaemonidae: are they a threat to survival?

Shrimps of the Palaemon genus have been affected for over 15 years by a problem of exoskeletal deformities, particularly in the Gironde estuary (France). Given the large numbers of individuals affected, this study focus on a better description of the phenomenon to estimate its impact on shrimps. This study, on Palaemon longirostris and Palaemon macrodactylus, is based on samples collected from 1992 to 2007 in the Gironde estuary with particular focus on the year 2007, and on a 4-month rearing of adult shrimps in experimental system. The different approaches reveal the relative persistence of the phenomenon since 1992 (with on average more than 58% of ovigerous females affected) and its persistence during shrimp life cycle, even after several moults. Important consequences associated with deformities at the individual level were demonstrated: a higher mortality, a lighter egg mass and a lower weight for a given size. The presence of exoskeletal deformities is now a major phenomenon, with profound effects on individual shrimps, and which may in turn have an important impact on the survival of the P. longirostris population in particular.

Production and biochemical characterization of a type B ferulic acid esterase from Streptomyces ambofaciens.

For the first time, the presence of a ferulic acid esterase (FAE) was demonstrated in Streptomyces ambofaciens. This extracellular enzyme was produced on a range of lignocellulosic substrates. The maximal level of activity was detected in the presence of either destarched wheat bran or oat spelt xylan as the sole carbon source. We found that 1% (m/v) of destarched wheat bran was the optimal concentration to induce its production. With this inducer, no ferulic acid dimers were released from the cell wall by the produced FAE. Interestingly, rape cattle cake (Brassica napus), which does not contain esterified ferulic acid, was also shown to induce the production of the FAE from S. ambofaciens. The FAE was partially purified from the culture supernatant. The purified enzyme was optimally active at pH 7 and 40 degrees C. The substrate specificity of the FAE from S. ambofaciens was investigated: the highest activity was determined with methyl p-coumarate, methyl ferulate, and methyl cinnamate. Furthermore, the FAE required a certain distance between the benzene ring and the ester bond to be active. According to these biochemical characteristics, the FAE from S. ambofaciens has been classified as a type B FAE.