Chondrus crispus treated with ultrasound as a polysaccharides source with improved antitumoral potential.

Ultrasound-assisted extraction was used to recover gelling biopolymers and antioxidant compounds from Chondrus crispus with improved biological potential. The optimal processing conditions were evaluated using a Box-Behnken design, and the impact on the biological and thermo-rheological properties of the carrageenan fraction and on the bioactive features of the soluble extracts were studied. The optimum extraction parameters were defined by extraction time of ~34.7 min; solid liquid ratio of ~2.1 g/100 g and ultrasound amplitude of ~79.0% with a maximum power of 1130 W. The dependent variables exhibited maximum carrageenan yields (44.3%) and viscoelastic modulus (925.9 Pa) with the lowest gelling temperatures (38.7 °C) as well as maximum content of the extract in protein (22.4 mg/g), gallic acid (13.4 mg/g) and Trolox equivalents antioxidant capacity (182.4 mg TEAC/g). Tested hybrid carrageenans exhibited promising biological activities (% of growth inhibition around 91% for four human cancer cellular lines: A549; A2780; HeLa 229; HT-29).

Rheological characteristics and supramolecular structure of the exopolysaccharide produced by Lactobacillus fermentum MTCC 25067.

Rheological properties and supramolecular structure of the exopolysaccharide (EPS) secreted by Lactobacillus fermentum MTCC 25067 were investigated. The critical concentration representing the lower-limit of the semi-dilute regime was estimated to be 0.71 g/L from the concentration dependence of zero-shear specific viscosity. The storage modulus (G') of a 20 g/L EPS solution was greater than the loss modulus (G″) at 0.1-25 Hz. Approximately linear increases in G' and G″ determined at a frequency of 1 Hz and a strain of 0.01 during cooling from 80 to 25 °C were an indication that the EPS did not undergo thermally-induced cooperative conformational transitions typical of gelling polysaccharides. Atomic force microscopy images revealed that EPS molecules were not completely dissociated into individual molecules in an aqueous solution but remained to form three-dimensional networks. The gel-like dynamic viscoelasticity of the 20 g/L EPS solution was thus attributed to the existence of supramolecular assemblies resulting from significant degrees of intermolecular association of the EPS in the solution.

Production of bacterial cellulose hydrogels with tailored crystallinity from Enterobacter sp. FY-07 by the controlled expression of colanic acid synthetic genes.

Hydrogels exhibit smart three-dimensional networks and extraordinary water-absorbing ability. To improve the water-holding capacity of bacterial cellulose hydrogels, the expression of a biosynthetic gene cluster of colanic acid, a water-soluble polysaccharide, was induced in Enterobacter sp. FY-07, which produces an abundance of bacterial cellulose hydrogel under aerobic and anaerobic fermentation conditions. The results indicated that in situ modified bacterial cellulose hydrogels with different crystallinities, rheological properties and water-holding capacities were produced by cultivating the engineered strain Enterobacter sp. FY-07::tac under different inducing conditions. The water-holding capacity of the modified bacterial cellulose hydrogel was enhanced by more than 1.7 fold compared to the hydrogel produced by Enterobacter sp. FY-07, and the networks of the modified bacterial cellulose hydrogel were densified but still clear. These results suggest that this in situ modification strategy endows bacterial cellulose hydrogels with improved properties and potentially expands their applications in biomedical fields and the food industry.

Structural characterization and rheological properties of a gel-like ß-d-glucan from Pholiota nameko.

A crude fraction (SCW) was extracted with cold water from Pholiota nameko and showed mannose (24.1%), galactose (44.9%) and glucose (31%). Purification procedures resulted in a polysaccharide fraction (bG-PN), that showed only glucose. NMR and methylation analyses of bG-PN indicated a ß-d-glucan-(1→3)-linked, substituted at O-6 by ß-d-Glcp or (1→6)-linked ß-d-Glcp side chains. Rheological studies of crude and purified fractions at the same concentration showed similar shear-thinning behavior and gel-like structure which indicates no need to isolate the polymer to achieve some desirable rheological properties. SCW (at 1% and 2%) and bG-PN (at 2%) presented thermal stability during heating and cooling, suggesting that the physical structure of gels (SCW and bG-PN at 2%) and viscoelastic fluid (SCW at 1%) formed were not altered in the tested temperature range. Our results suggest that P. nameko ß-d-glucans can be applied in different food preparations as thickener or gelling agents modifying their rheological properties.

Recovery, viscoelastic and functional properties of Barbel skin gelatine: investigation of anti-DPP-IV and anti-prolyl endopeptidase activities of generated gelatine polypeptides.

The characteristics and functional properties of gelatine from freshwater fish skin (Barbus callensis) were investigated. The gelatine extraction efficiency was improved by an acid-swelling process in the presence of barbel crude acid protease extract. Barbel skin gelatine (BSG) contained 92.15% protein, 0.31% lipid and 0.72% ash. The amino acid profile of BSG showed a high percentage of imino acids. The electrophoretic profile showed that BSG is mainly composed of α- and ß-components. BSG showed an excellent solubility and possessed interfacial properties, which were governed by the protein concentration. Biological activities of the hydrolysates obtained after digestion of BSG with several commercial proteases were evaluated. The results suggested that these hydrolysates are a good source of natural inhibitors of dipeptidyl peptidase-IV and prolyl endopeptidase and could potentially be used as dietary ingredients in the management of type 2-diabetes and/or neuropathological disorders.

Ophthalmic viscoelastic devices as a cleaning challenge.

Common practice when validating the cleaning of medical devices is to employ clinically relevant test soils as a challenge to the cleaning process. During use, medical devices may come into contact with a variety of materials that are difficult to clean. One example of this is the use of ophthalmic viscoelastic devices (OVDs) in cataract surgery. This study evaluated the effectiveness of a procedure for cleaning the lumens of a phacoemulsification handpiece using two different OVDs as test soils. The results of this study demonstrate that effective cleaning of the aspiration and irrigation lumens of a phacoemulsification handpiece may be achieved if the manufacturer's recommended cleaning procedures are followed.

[Characteristics of Pseudomonas aurantiaca DNA supramolecular complexes at various developmental stages].

Differences in viscoelasticity (eta) and molecular mass (M) values, as well as in the fatty acid profile of lipids in DNA supramolecular complexes (SC) isolated from Pseudomonas aurantiaca cultures at the exponential and stationary growth phases were established for the first time. Typical characteristics of DNA SC from actively growing cells were the following: eta = 315 +/- 15 dl/g, M(DNA) = 39 x 10(6) Da, C16:0 > C18:0 > C18:1 present as basic fatty acids (FA) in a pool of loosely DNA-bound lipids; the tightly DNA-bound lipid fraction consisted of only two acids C18:0 > C16:0. Significantly higher values of viscoelasticity eta = 779 +/- 8 dl/g and M(DNA) = 198 x 10(6) Da were observed for DNA SC of the stationary phase cells; one more FA, C14:0, was detected in the loosely bound lipid fraction, while lipids tightly bound to DNA contained mainly C16:0 > C18:1 > > C18:0 > C14:0 FA. The content of saturated FA in the DNA-bound lipids in the stationary phase cells was twice as high as in the exponential phase cells. The fraction of tightly bound lipids from the stationary phase cells contained nine times more unsaturated fatty acids than the fraction from proliferating cells. These differences in FA composition of DNA-bound lipids demonstrate the importance of lipids for the structural organization and functioning of genomic DNA during bacterial culture development.