Evaluating the durability and performance of polyoxometalate-ionic liquid coatings on calcareous stones: Preventing biocolonisation in outdoor environments

Rock-based materials exposed to outdoor environments are naturally colonised by an array of microorganisms, which can cause dissolution and fracturing of the natural stone. Biocolonisation of monuments and architectures of important cultural heritage therefore represents an expensive and recurring problem for local authorities and private owners alike. In this area, preventive strategies to mitigate biocolonisation are generally preferred to curative approaches, such as mechanical cleaning by brush or high-pressure cleaning, to remove pre-existing patina. The aim of this work was to study the interaction between biocidal polyoxometalate-ionic liquid (POM-IL) coatings and calcareous stones and evaluate the capacity of these coatings to prevent biocolonisation through a series of accelerated ageing studies in climate chambers, carried out in parallel with a two-year period of outdoor exposure in north-eastern France. Our experiments show that POM-IL coatings did not affect water vapour transfer nor significantly alter the total porosity of the calcareous stones. Simulated weathering studies replicating harsh (hot and wet) climatic weather conditions demonstrated that the colour variation of POM-IL-coated stones did not vary significantly with respect to the natural uncoated stones. Accelerated biocolonisation studies performed on the weathered POM-IL-coated stones proved that the coatings were still capable of preventing colonisation by an algal biofilm. However, a combination of colour measurements, chlorophyll fluorescence data, and scanning electron microscopy imaging of stones aged outdoors in northern France for two years showed that coated and uncoated stone samples showed signs of colonisation by fungal mycelium and phototrophs. Altogether, our results demonstrate that POM-ILs are suitable as preventative biocidal coatings for calcareous stones, but the correct concentrations must be chosen to achieve a balance between porosity of the stone, the resulting colour variation and the desired duration of the biocidal effect over longer periods of time, particularly in outdoor environments

New protective coatings against lampenflora growing in the Pommery Champagne cellar

Phototrophic microorganisms such as cyanobacteria and microalgae can proliferate readily in underground heritage sites where the introduction of artificial illumination equipment has significantly altered previously stable environmental conditions. The extended lampenflora biofilm growth on the bas-reliefs carved in the underground Pommery Champagne cellar in Reims (France) represents a recurring biocolonisation problem which requires periodic cleaning. The aim of this work was to limit the growth of lampenflora on chalk substrates using preventative biocidal treatments based on polyoxometalate ionic liquids (POM-ILs). Biocidal assays carried out in laboratory showed how two different colourless POM-IL coatings were more effective than commercial Preventol RI80 against two algal strains isolated from the Pommery bas reliefs, Pseudostichococcus monallantoides and Chromochloris zofingiensis. However, only one POM-IL variant was capable of sustained prevention of biofilm growth when applied to wet chalk, which replicates the more drastic natural environmental conditions of the cellar and can limit the performance of the biocidal coatings. Crucially, coating concentration studies demonstrate how POM-IL-coated slabs from previous experiments retain their biocidal activity and can prevent subsequent recolonisation following the re-inoculation of coated slabs with algae and cyanobacteria. Consequently, POM-ILs represent excellent candidates to eliminate lampenflora growth on the chalk bas-reliefs in the unique subterranean environment of the Pommery Champagne cellar. © 2022 The Author

Taxonomy, Physiology, and Natural Products of Actinobacteria

Microbial Biotechnolog

Effets de fongicides anti-Botrytis sur les organes végétatifs et reproducteurs de la vigne

Au vignoble, l utilisation de fongicides est indispensable pour lutter contre la pourriture grise, causée par le pathogène Botrytis cinerea. L application de fongicides anti-Botrytis est recommandée à trois stades de développement de la vigne : fin floraison (stade A), fermeture de la grappe (stade B) et début véraison (stade C). Parmi ces fongicides, le fludioxonil et le fenhexamid, qui appartiennent à des familles chimiques différentes, sont couramment utilisés. Dans un objectif de limitation d emploi des pesticides, il est nécessaire de mieux connaître les effets de ces produits sur la physiologie de la plante. L impact de ces fongicides anti-Botrytis a donc été évalué à la fois sur les organes végétatifs et reproducteurs de la vigne. En effet, les organes végétatifs, par leur activité photosynthétique, assurent la nutrition nécessaire à la croissance de la plante. Concernant les organes reproducteurs, leur développement va déterminer le rendement. La photosynthèse a donc été utilisée comme paramètre physiologique afin d étudier le stress provoqué par les fongicides sur les organes végétatifs. Les réponses de défense ont également été évaluées puisque le stress chimique, généré par les traitements anti-Botrytis, pourrait activer ces réponses. Concernant les effets des fongicides sur les organes reproducteurs, des facteurs pouvant influencer leur efficacité ont été évalués : (i) le stade de traitement, (ii) le mode d action du fongicide, (iii) la pression de sélection exercée par les fongicides sur le pathogène et enfin (iv) les réponses de défense de la vigneIn the vineyard, the use of fungicides is necessary to control grey mould caused by the phytopathogenic Botrytis cinerea. Three applications of botryticides are recommended: at the end of flowering (stage A), at bunch closure (stage B), and at the beginning of berry ripening (stage C). Fludioxonil and fenhexamid belong to two different chemical classes and are commonly used as botryticides. To reduce pesticide use, it s necessary to improve the knowledge about chemical effects on plant physiology. Therefore, effects of these botryticides have been evaluated on grapevine vegetative and reproductive organs. Indeed, photosynthesis performed in vegetative organs provides the energy and structural substrates for plant growth. Considering reproductive organs, their development is related to the yield. Therefore, the photosynthesis was used as a physiological parameter to study stress caused by fungicides on vegetative organs. Plant defense responses have also been analysed because chemical stress induced by botryticides could activate these responses. Considering the fungicide effects on reproductive organs, various factors which could influence their efficacy were followed: (i) treatment stage, (ii) fungicide mode of action, (iii) selection pressure exerted by fungicides on B. cinerea and (iv) grapevine defense responsesREIMS-BU Sciences (514542101) / SudocSudocFranceF

Correction for Barka et al., Taxonomy, Physiology, and Natural Products of Actinobacteria (vol 80, pg 1, 2016)

Microbial Biotechnolog

Low source-sink ratio reduces reserve starch in grapevine woody canes and modulates sugar transport and metabolism at transcriptional and enzyme activity levels

Severe leaf removal decreases storage starch and sucrose in grapevine cv. Cabernet Sauvignon fruiting cuttings and modulates the activity of key enzymes and the expression of sugar transporter genes.The work was supported by European Union Funds (INTERACT-NORTE-01-0145-FEDER-000017-Linha VitalityWineON 0013), Portuguese national funds (FCT-Portuguese Foundation for Science and Technology) under the Project UID/AGR/04033/2013 and the Conseil Interprofessionnel du Vin de Bordeaux (CIVB, France) under the Project CANOGRAPE N 44233. HN (SFRH/BPD/ 115518/2016) was supported by postdoctoral grant from FCT.info:eu-repo/semantics/publishedVersio