Fungal biodetector: a real-time indoor air quality monitoring

International audienceFungi are common biocontaminants of indoor environments, and numerous studies have demonstrated how they can degrade the materials they colonise (e.g. wood, textiles, paper, pigments, varnishes, etc.), which can even result in total destruction of these substrates. Today, fungal contamination is an increasing problem in houses, working places, schools, hospitals, elderly care centers and cultural heritage. Current techniques are unable to detect mould at an early stage in their development or hidden contaminants. Moularat et al. (2008) has established chemical fingerprints of mouldy development from Volatile Organic Compounds (VOCs) arising specifically from fungal metabolism. This approach has the advantage of detecting fungal development both reliably and rapidly before any visible signs of contamination could be detected. Since the development of this Fungal Contamination Index (FCI), other specific indexes have been developed to monitor Invasive Nosocomial Aspergillosis in hospitals or Serpula Lacrymans in dwellings. Their applications constitute a new approach for diagnosis. However, even if the FCI has been widely tested, VOCs'analysis by GC/MS, which is required for index calculation, is incompatible for indoor environment real-time monitoring strategy. So having such a device, which could be set up in buildings and able to provide almost instantaneous information on prospective fungal development, constitutes a breakthrough. In this context, researches around FCI exploitation have been followed up in order to provide a device widely deployable which enables mould development real-time monitoring. This innovative microsystem is the result of the miniaturization of an analytical chain for portable, reliable and low-cost applications. This biodetector was the subject of patent applications by the CSTB

Etude de la contamination fongique des environnements intérieurs par la détermination et la mesure de traceurs chimiques spécifiques : application à l'hygiène de l'habitat

Disease occurrence in mouldy environments is very widely described in the literature. Health effects of moulds and associated metabolites are numerous: infection, allergy, toxi-infection, irritations. Prevalence and severity of declared diseases in the childs and adults seem correlated with an increase of indoor contaminated surfaces. However, the characterization of occupant exposure remains underestimated. The object of this work is essentially focused on the development of analytical methods to determine microbiological indoor quality, the definition and validation of survey indicators. This research is thus both aimed at the development and improvement of sampling techniques and also on the conception and adaptation of direct and indirect measurements methods of metabolism products ( Specific VOC) or of specific cellular components (Ergosterol, mycotoxins). The study of VOC of fungus origin enabled the definition of relevant chemical tracers associated with fungus development. >From these compounds, we established an index of fungus contamination in the indoor environments. Samplings realized in 12 houses allowed the validation of this index. Besides, an original methodology of quantification of mould exposure was proposed taking into account the evaluation of biomass and airborne mycotoxins. The transfer rate of material-air of a mycotoxin (the sterigmatocystin) was also studied.L'apparition de maladies chez les occupants d'environnements «moisis» a été très largement décrite dans la littérature. Les effets sur la santé des moisissures et métabolites associés sont nombreux : infections, allergies, toxi-infections, irritations. La prévalence et la sévérité des maladies déclarées chez l'enfant et l'adulte semblent corrélées avec une augmentation des surfaces contaminées dans l'habitat. Cependant, la caractérisation de l'exposition des personnes reste méconnue. L'objet du travail de thèse a essentiellement porté sur le développement de méthodes d'analyse de la qualité microbiologique des milieux, la définition et la validation d'indicateurs de surveillance de cette qualité. Ainsi, cette recherche a porté à la fois sur le développement et l'amélioration des techniques de prélèvement mais également sur la mise au point et l'adaptation de méthodes de dosage et de reconnaissance indirecte, basées en particulier sur la recherche des produits du métabolisme (COV spécifiques) ou de constituants cellulaires spécifiques (Ergostérol, mycotoxines). L'étude des COV d'origine fongique a permis de définir une liste de 18 traceurs chimiques pertinents associés à un développement fongique. A partir de l'étude de ces composés, nous avons établi un indice de contamination fongique des locaux. Des prélèvements in situ réalisés dans 12 habitations ont permis la validation de cet indice. Par ailleurs, une méthodologie originale de quantification de l'exposition aux moisissures par l'évaluation de la biomasse et des mycotoxines aéroportées a été proposée. Le taux de transfert matériau-air d'une mycotoxine (la stérigmatocystine) a également été étudié

Etude de la contamination fongique des environnements intérieurs par la détermination et la mesure de traceurs chimiques spécifiques (application à l'hygiène de l'habitat)

L apparition de maladies chez les occupants d environnements moisis a été très largement décrite dans la littérature. Les effets sur la santé des moisissures et métabolites associés sont nombreux : infections, allergies, toxi-infections, irritations. La prévalence et la sévérité des maladies déclarées chez l enfant et l adulte semblent corrélées avec une augmentation des surfaces contaminées dans l habitat. Cependant, la caractérisation de l exposition des personnes reste méconnue. L objet du travail de thèse a essentiellement porté sur le développement de méthodes d analyse de la qualité microbiologique des milieux, la définition et la validation d indicateurs de surveillance de cette qualité. Ainsi, cette recherche a porté à la fois sur le développement et l'amélioration des techniques de prélèvement mais également sur la mise au point et l'adaptation de méthodes de dosage et de reconnaissance indirecte, basées en particulier sur la recherche des produits du métabolisme (COV spécifiques) ou de constituants cellulaires spécifiques (Ergostérol, mycotoxines). L étude des COV d origine fongique a permis de définir une liste de 18 traceurs chimiques pertinents associés à un développement fongique. A partir de l étude de ces composés, nous avons établi un indice de contamination fongique des locaux. Des prélèvements in situ réalisés dans 12 habitations ont permis la validation de cet indice. Par ailleurs, une méthodologie originale de quantification de l exposition aux moisissures par l évaluation de la biomasse et des mycotoxines aéroportées a été proposée. Le taux de transfert matériau-air d une mycotoxine (la stérigmatocystine) a également été étudiéDisease occurrence in mouldy environments is very widely described in the literature. Health effects of moulds and associated metabolites are numerous: infection, allergy, toxi-infection, irritations. Prevalence and severity of declared diseases in the childs and adults seem correlated with an increase of indoor contaminated surfaces. However, the characterization of occupant exposure remains underestimated. The object of this work is essentially focused on the development of analytical methods to determine microbiological indoor quality, the definition and validation of survey indicators. This research is thus both aimed at the development and improvement of sampling techniques and also on the conception and adaptation of direct and indirect measurements methods of metabolism products ( Specific VOC) or of specific cellular components (Ergosterol, mycotoxins). The study of VOC of fungus origin enabled the definition of relevant chemical tracers associated with fungus development. >From these compounds, we established an index of fungus contamination in the indoor environments. Samplings realized in 12 houses allowed the validation of this index. Besides, an original methodology of quantification of mould exposure was proposed taking into account the evaluation of biomass and airborne mycotoxins.The transfer rate of material-air of a mycotoxin (the sterigmatocystin) was also studiedPARIS-EST Marne-la-Vallee-BU (774682101) / SudocSudocFranceF

A new approach to detect early or hidden fungal development in indoor environments

International audienceIn addition to the biodegradation problems encountered in buildings, exposure of their occupants to mold is responsible for numerous diseases such as respiratory infections, immediate or delayed allergies and different types of irritations. However, current techniques are unable to detect mold at an early stage of development or hidden contaminants.Moularat et al., in 2008 has established chemical fingerprints of moldy growth from Volatile Organic Compounds (VOCs) arising specifically from fungal metabolism and developed the Fungal Contamination Index (FCI) (Moularat et al., 2008a,b). This index has the advantage of detecting fungal development both reliably and rapidly before any visible signs of contamination could be detected.However, even though the FCI has been widely tested, VOCs’ analysis by GC/MS, which is required for index calculation, is incompatible with real-time monitoring strategy for indoor environments.In this context, researches around FCI exploitation have been followed up in order to provide a monitoring device widely deployable which is the result of the miniaturization of an analytical chain for portable, reliable and low-cost applications. This device is based on one hand the selection and concentration of chemical compounds from the sample of interest and on the other hand the development of an array of different conducting polymer based sensors in order to obtain a specific footprint.This fungal contamination detection device was the subject of patent applications by the CSTB.The modularity of the system (ability to vary both the elements of detection polymers and retention time of interest) allows for expansion of its use to other pollutants

Fungal biodetector: a real-time indoor air quality monitoring

International audienceFungi are common biocontaminants of indoor environments, and numerous studies have demonstrated how they can degrade the materials they colonise (e.g. wood, textiles, paper, pigments, varnishes, etc.), which can even result in total destruction of these substrates. Today, fungal contamination is an increasing problem in houses, working places, schools, hospitals, elderly care centers and cultural heritage. Current techniques are unable to detect mould at an early stage in their development or hidden contaminants. Moularat et al. (2008) has established chemical fingerprints of mouldy development from Volatile Organic Compounds (VOCs) arising specifically from fungal metabolism. This approach has the advantage of detecting fungal development both reliably and rapidly before any visible signs of contamination could be detected. Since the development of this Fungal Contamination Index (FCI), other specific indexes have been developed to monitor Invasive Nosocomial Aspergillosis in hospitals or Serpula Lacrymans in dwellings. Their applications constitute a new approach for diagnosis. However, even if the FCI has been widely tested, VOCs'analysis by GC/MS, which is required for index calculation, is incompatible for indoor environment real-time monitoring strategy. So having such a device, which could be set up in buildings and able to provide almost instantaneous information on prospective fungal development, constitutes a breakthrough. In this context, researches around FCI exploitation have been followed up in order to provide a device widely deployable which enables mould development real-time monitoring. This innovative microsystem is the result of the miniaturization of an analytical chain for portable, reliable and low-cost applications. This biodetector was the subject of patent applications by the CSTB

Study of colonization mechanisms of construction products by micromycetes applied to the development of a preventive treatment

International audienceBackground: In nature, saprotrophic fungi have an essential ecological role in decomposition of organic matter. In soils, they break down material like leaves, wood, dead bodies, etc. Fungal colonization in natural environments requires advanced functional relationships, including various antagonisms and synergisms, between the different components of the biotope. Colonization can be described, analyzed at different scales (macroscopic and molecular) and modeled. In indoor environment, fungi find niches favorable to their development, but are most often undesirable. Indeed, micromycetes induce pathologies to the occupants (allergies, poisoning and infections) and can also cause irreversible damages to the materials they infest. Colonization of different man-made substrates (construction and decoration products) by mold is insufficiently described to develop colonization models: Is artificial substrate colonization done serendipitously or is it determined like in natural environment by a defined succession of fungi driven by antagonisms and synergisms? A better knowledge of the dynamic of fungal colonization would be helpful to imagine preventive strategy for health and artifacts preservation. Objectives: In this context, our research in microbial ecology aims to describe and understand the fungal colonization mechanisms in enclosed spaces. Methods: First, a macroscopic characterization of the fungal succession on two artificial substrates has been made by culture and molecular methods. Secondly, Volatile Organic Compounds (VOC’s) emitted by microfungi according to the growth substrates have been explored. Conclusions: This new knowledge will offer alternatives to slow and limit fungal growth on building products to the use of traditional biocides

Airborne fungal volatile organic compounds in rural and urban dwellings detection of mould contamination in 94 homes determined by visual inspection and airborne fungal volatile organic compounds method.

International audienceMoulds can both degrade the materials and structures they colonise and contribute to the appearance of symptoms and diseases in the inhabitants of contaminated dwellings. Only few data have compared the levels of contamination in urban and rural environments and the results are not consistent. The aim of this study was to use a fungal contamination index, based on the detection of specific Microbial Volatile Organic Compounds (MVOC), to determine the exposure to moulds of individuals living in urban and rural dwellings. For this purpose, 94 dwellings (47 in an urban setting in Clermont-Ferrand and 47 in rural areas of the Auvergne region, France) were studied. By demonstrating marked disparities between the proportion of visible contamination (19%) and that of active, visible and/or hidden contamination (59%) and the fact that almost all visible contamination was identified by MVOC, we were able to show that use of the index seemed relevant to confirm the actual presence of fungal contamination in a dwelling. Furthermore, it was possible to demonstrate a relationship between moulds and the presence of water on surfaces (condensation, infiltrations, water damage, etc.). A higher proportion of positive fungal contamination index in rural homes was observed compared to the proportion in urban ones (68% versus 49%; p<0.05)

Study of colonization mechanisms of construction products by micromycetes applied to the development of a preventive treatment

International audienceBackground: In nature, saprotrophic fungi have an essential ecological role in decomposition of organic matter. In soils, they break down material like leaves, wood, dead bodies, etc. Fungal colonization in natural environments requires advanced functional relationships, including various antagonisms and synergisms, between the different components of the biotope. Colonization can be described, analyzed at different scales (macroscopic and molecular) and modeled. In indoor environment, fungi find niches favorable to their development, but are most often undesirable. Indeed, micromycetes induce pathologies to the occupants (allergies, poisoning and infections) and can also cause irreversible damages to the materials they infest. Colonization of different man-made substrates (construction and decoration products) by mold is insufficiently described to develop colonization models: Is artificial substrate colonization done serendipitously or is it determined like in natural environment by a defined succession of fungi driven by antagonisms and synergisms? A better knowledge of the dynamic of fungal colonization would be helpful to imagine preventive strategy for health and artifacts preservation. Objectives: In this context, our research in microbial ecology aims to describe and understand the fungal colonization mechanisms in enclosed spaces. Methods: First, a macroscopic characterization of the fungal succession on two artificial substrates has been made by culture and molecular methods. Secondly, Volatile Organic Compounds (VOC’s) emitted by microfungi according to the growth substrates have been explored. Conclusions: This new knowledge will offer alternatives to slow and limit fungal growth on building products to the use of traditional biocides

Design optimisation of silicon-based MEMS sensors dedicated to bioaerosols monitoring

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Discrimination of gas-phase emissions from building material samples by combining two gas-sensor arrays

International audienceAs part of the European project SYSPAQ, aiming at the conception of sensor systems to measure perceived air quality, experiments have been performed to assess the discrimination power of two gas-sensor systems as regards typical building material emissions. The first is based on individual metal oxide sensors and the second more compact constituted by a segmented sputtered layer of Pt-doped tin oxide differentiated by a temperature gradient and a thickness variation of a gas permeable SiO2 coating. The 2 systems are intended to be integrated in a larger system in the framework of the project. The objective of the preliminary experiments presented here is to check the discrimination performance of the merged system to emissions of 20 building materials