Evaluation of antimicrobial effectiveness of pimaricin-loaded thermosensitive nanohydrogels in grape juice

Pimaricin-loaded poly(N-isopropylacrylamide) nanohydrogels with and without acrylic acid, were evaluated as food-spoilage inhibitors in a model system and a real food product: grape juice. Pimaricin was proposed as a non-allergenic alternative to sulphites for protecting juices against recontamination. However, pimaricin may degrade under conditions and treatments (heating, acidification, lighting) commonly applied in producing fresh juices. Nanohydrogel encapsulation may be a feasible procedure to avoid pimaricin degradation, improving its antimicrobial activity. Pimaricin-free nanohydrogels did not affect the growth of the indicator yeast either in the food model system or in grape juice. Conversely, pimaricin-loaded nanohydrogels effectively inhibited the growth of the indicator yeast. In some cases, the inhibition was extended even further than using free pimaricin. For instance, in the food model system, pimaricin-loaded nanohydrogels with acrylic acid (NPPNIPA-20AA(5)) prevented the yeast growth for more than 81 h while free pimaricin was only effective for 12 h. Despite pimaricin-loaded nanohydrogels without acrylic acid (NPPNIPA(5)) were able to reduce maximum yeast growth, as in all treatments with pimaricin, the extent of the inhibitory effect was not significantly (p>0.05) different to that achieved with free pimaricin. In grape juice, both free pimaricin and NPPNIPA-20AA(5) treatment completely inhibited the growth of the indicator yeast until the end of the bioassay. However, the latter provided similar inhibition levels using a smaller amount of pimaricin due to PNIPA-20AA(5) protection and its controlled release from the nanohydrogel. Therefore, nanohydrogel encapsulation may help to optimise antifungal treatments and decrease the incidence of food allergies.Funded by grant (MAT 2006-11662-CO3-CO2-C01/MAT 2010-21509-C03-01/EUI 2008-00115) from the “Ministerio de Educación y Ciencia” (Spain). Grant (SFRH/BPD/87910/2012) from the Fundação para a Ciência e Tecnologia (FCT, Portugal). Marie Curie COFUND Postdoctoral Research Fellow

Defensive properties of pyrrolizidine alkaloids against microorganisms

The understanding of the selection factors that drive chemical diversification of secondary metabolites of constitutive defence systems in plants, such as pyrrolizidine alkaloids (PAs), is still incomplete. Historically, plants always have been confronted with microorganisms. Long before herbivores existed on this planet, plants had to cope with microbial pathogens. Therefore, plant pathogenic microorganisms may have played an important role in the early evolution of the secondary metabolite diversity. In this review, we discuss the impact that plant-produced PAs have on plant-associated microorganisms. The objective of the review is to present the current knowledge on PAs with respect to anti-microbial activities, adaptation and detoxification by microorganisms, pathogenic fungi, root protection and PA induction. Many in vitro experiments showed effects of PAs on microorganisms. These results point to the potential of microorganisms to be important for the evolution of PAs. However, only a few in vivo studies have been published and support the results of the in vitro studies. In conclusion, the topics pointed out in this review need further exploration by carrying out ecological experiments and field studies

Les antijésuites

Ce livre propose une remontée aux sources méconnues de l’antijésuitisme, en amont de l’époque contemporaine, et principalement du XIXe siècle, où le « jésuite » a finalement représenté le comble de l’ecclésiastique dans un espace social, culturel, politique profondément clivé par l’affrontement du clergé et de l’esprit anticlérical. Il en va tout autrement de l’époque moderne, qui fournit une grande partie des motifs polémiques dont hériteront les siècles suivants, mais qui (parallèlement et dans un échange constant avec la Compagnie de Jésus elle-même, prompte dès sa naissance, au milieu du XVIe siècle, à instruire son procès en plaidant sa défense) présente à notre regard un paysage essentiellement différent : l’antijésuitisme s’y manifeste comme une série de synthèses souvent fragiles, mais redoutablement efficaces, entre une opposition à la « modernité », que la Compagnie, comme seul grand ordre moderne, incarne, et une opposition à la catholicité romaine, dont cette même Compagnie représente la dernière formation. L’antijésuitisme, ou les antijésuitismes : car c’est en traversant des textes, des situations locales et ponctuelles et des évolutions à l’échelle de deux siècles, dans l’Europe et dans le monde, que ce volume parvient à expliquer comment, à des niveaux de culture très variables, le jésuite, et radicalement le complot jésuite, ont pu figurer un fantastique exutoire des contradictions de l’époque moderne

Effects of three heavy metals on the bacteria growth kinetics: a bivariate model for toxicological assessment

The effects of three heavy metals (Co, Ni and Cd) on the growth kinetics of five bacterial strains with different characteristics (Pseudomonas sp., Phaeobacter sp. strain 27-4, Listonella anguillarum, Carnobacterium piscicola and Leuconostoc mesenteroides subsp. lysis) were studied in a batch system. A bivariate model, function of time and dose, is proposed to describe simultaneously all the kinetic profiles obtained by incubating a microorganism at increasing concentrations of individual metals. This model combines the logistic equation for describing growth, with a modification of the cumulative Weibull’s function for describing the dose-dependent variations of growth parameters. The comprehensive model thus obtained—which minimizes the effects of the experimental error—was statistically significant in all the studied cases, and it raises doubts about toxicological evaluations that are based on a single growth parameter, especially if it is not obtained from a kinetic equation. In lactic acid bacteria cultures (C. piscicola and L. mesenteroides), Cd induced remarkable differences in yield and time course of characteristic metabolites. A global parameter is defined (ED50,τ: dose of toxic chemical that reduces the biomass of a culture by 50% compared to that produced by the control at the time corresponding to its semi maximum biomass) that allows comparing toxic effects on growth kinetics using a single value.Peer reviewe