In the last decade, an increasing number of glycosaminoglycans (GAGs), chitin and chitosan applications have been reported. Their commercial demands have been extended to different markets, such as cosmetics, medicine, biotechnology, food and textiles. Marine wastes from fisheries and aquaculture are susceptible sources for polymers but optimized processes for their recovery and production must be developed to satisfy such necessities. In the present work, we have reviewed different alternatives reported in the literature to produce and purify chondroitin sulfate (CS), hyaluronic acid (HA) and chitin/chitosan (CH/CHs) with the aim of proposing environmentally friendly processes by combination of various microbial, chemical, enzymatic and membranes strategies and technologies.

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Headline: Inhibition of pathogenic microbiota SUMMARYThe concrete nature of the probiotic effects that the presence of microorganisms (especially lactic acid bacteria: LAB) exercise on larval cultures of fish, it is not well defined, being been able to attribute to different factors or action mechanisms. In fact, the production of diverse antibacterial metabolites (bacteriocins in particular) by many LAB forms are able to constitute the basis of these probiotic effects, as repeatedly described in the literature. Accordingly, the inhibition of fish pathogenic species by extracts of LAB constitutes a rapid method for detecting potential probiotics. By studying the response of four common pathogens of turbot (Scophthalmus maximus) to nine potential probiotics, the diversity and mechanisms of effectors in the probiotics were demonstrated to present complex profiles dose-response and non-treatable with conventional models. Proposed modifications allow satisfactory fits and the calculation of useful parameters in the comparison of activities. The results showed that lactic and acetic acid, and not the bacteriocins, are responsible for effects (inhibitory or stimulatory depending on the concentrations considered) in all the cases studied.

The β-carotene bleaching assay, a common method for evaluating antioxidant activity, has been widely criticized due to its low reproducibility, problematic quantification, complex reagent preparation, and interference of different factors (temperature, pH, solvents, and metals). In this work we have examined the effects of these factors and developed a highly reproducible procedure for microplate assay, evaluated the critical points of the method, and proposed a kinetic model for quantifying both antioxidant and prooxidant activities. The application of these tools produced very consistent results, which provide robust and meaningful criteria to compare in detail the characteristics of several well-known commercial antioxidants, as well as several predictable prooxidants, and can be easily applied to natural extracts, food samples, and many other type of compounds. As an example, we have tested a set of commercial antioxidants and some typical lipophilic prooxidants. The activity of the tested antioxidants decreased in the following order: ethoxyquin ≫ α-tocopherol > butylhydroxyanisole > butylhydroxytoluene ≫ propyl gallate. On the other hand, hemoglobin and Fe(2+), Fe(3+), Co(2+), and Cu(2+) showed a strong prooxidant effect, and the activity was null in Cd(2+), Ni(2+), and Sr(2+), slightly antioxidant in Mg(2+), and strongly antioxidant in Zn(2+) and Mn(2+).

M.L. CABO, M.A. MURADO, M.P. GONZÁ L E Z A ND L . P AS T OR IZ A . 1999. Different aspects of the most commonly used assay methods in the study of bacteriocins were examined. The conditions under which extraction and incubation (including exposure time) take place were analysed, and several different formal models that are usually employed to calculate ID 50 were compared. As an alternative designed to overcome the problems which characterize the response of micro-organisms that are sensitive to bacteriocins, an operative procedure in a liquid medium and a modified re-parameterized logistic equation is proposed. When applied to the inhibition of Leuconostoc mesenteroides by nisin, the model allows an optimal experimental procedure to be defined.