The effectiveness of anaerobic digestion in removing estrogens and nonylphenol ethoxylates

This is the post-print version of the final paper published in Journal of Hazardous Materials. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2011 Elsevier B.V.The fate and behaviour of two groups of endocrine disrupting chemicals, steroid estrogens and nonylphenol ethoxylates, have been evaluated during the anaerobic digestion of primary and mixed sewage sludge under mesophilic and thermophilic conditions. Digestion occurred over six retention times, in laboratory scale reactors, treating sludges collected from a sewage treatment works in the United Kingdom. It has been established that sludge concentrations of both groups of compounds demonstrated temporal variations and that concentrations in mixed sludge were influenced by the presence of waste activated sludge as a result of transformations during aerobic treatment. The biodegradation of total steroid estrogens was >50% during primary sludge digestion with lower removals observed for mixed sludge, which reflected bulk organic solids removal efficiencies. The removal of nonylphenol ethoxylates was greater in mixed sludge digestion (>58%) compared with primary sludge digestion and did not reflect bulk organic removal efficiencies. It is apparent that anaerobic digestion reduces the concentrations of these compounds, and would therefore be expected to confer a degree of protection against exposure and transfer of both groups of compounds to the receiving/re-use environment.Thames Water, Yorkshire Water, and EPSRC

Screening of Phytophagous and Xylophagous Insects Guts Microbiota Abilities to Degrade Lignocellulose in Bioreactor

Microbial consortia producing specific enzymatic cocktails are present in the gut of phytophagous and xylophagous insects; they are known to be the most efficient ecosystems to degrade lignocellulose. Here, the ability of these consortia to degrade ex vivo lignocellulosic biomass in anaerobic bioreactors was characterized in term of bioprocess performances, enzymatic activities and bacterial community structure. In a preliminary screening, guts of Ergates faber (beetle), Potosia cuprea (chafer), Gromphadorrhina portentosa (cockroach), Locusta migratoria (locust), and Gryllus bimaculatus (cricket) were inoculated in anaerobic batch reactors, in presence of grounded wheat straw at neutral pH. A short duration fermentation of less than 8 days was observed and was related to a drop of pH from 7 to below 4.5, leading to an interruption of gas and metabolites production. Consistently, a maximum of 180 mgeq.COD of metabolites accumulated in the medium, which was related to a low degradation of the lignocellulosic biomass, with a maximum of 5 and 2.2% observed for chafer and locust gut consortia. The initial cell-bound and extracellular enzyme activities, i.e., xylanase and β-endoglucanase, were similar to values observed in the literature. Wheat straw fermentation in bioreactors leads to an increase of cell-bounded enzyme activities, with an increase of 145% for cockroach xylanase activity. Bacterial community structures were insect dependent and mainly composed of Clostridia, Bacteroidia and Gammaproteobacteria. Improvement of lignocellulose biodegradation was operated in successive batch mode at pH 8 using the most interesting consortia, i.e., locust, cockroaches and chafer gut consortia. In these conditions, lignocellulose degradation increased significantly: 8.4, 10.5, and 21.0% of the initial COD were degraded for chafer, cockroaches and locusts, respectively in 15 days. Consistently, xylanase activity tripled for the three consortia, attesting the improvement of the process. Bacteroidia was the major bacterial class represented in the bacterial community for all consortia, followed by Clostridia and Gammaproteobacteria classes. This work demonstrates the possibility to maintain apart of insect gut biological activity ex vivo and shows that lignocellulose biodegradation can be improved by using a biomimetic approach. These results bring new insights for the optimization of lignocellulose degradation in bioreactors

Species richness influences wine ecosystem function through a dominant species

Increased species richness does not always cause increased ecosystem function. Instead, richness can influence individual species with positive or negative ecosystem effects. We investigated richness and function in fermenting wine, and found that richness indirectly affects ecosystem function by altering the ecological dominance of Saccharomyces cerevisiae. While S. cerevisiae generally dominates fermentations, it cannot dominate extremely species-rich communities, probably because antagonistic species prevent it from growing. It is also diluted from species-poor communities, allowing yeasts with lower functional impacts to dominate. We further investigated the impacts of S. cerevisiae and its competitors in high- and low-functioning wine communities, focusing on glucose consumption as an ecosystem function. S. cerevisiae is a keystone species because its presence converts low-functioning communities to communities with the same function as S. cerevisiae monocultures. Thus, even within the same ecosystem, species richness has both positive and negative effects on function

Sustaining rare marine microorganisms: macroorganisms as repositories and dispersal agents of microbial diversity

Recent analyses revealed that most of the biodiversity observed in marine microbial communities is represented by organisms with low abundance but, nonetheless essential for ecosystem dynamics and processes across both temporal and spatial scales. Surprisingly, few studies have considered the effect of macroorganism-microbe interactions on the ecology and distribution dynamics of rare microbial taxa. In this review, we synthesize several lines of evidence that these relationships cannot be neglected any longer. First, we provide empirical support that the microbiota of macroorganisms represents a significant part of marine bacterial biodiversity and that host-microbe interactions benefit to certain microbial populations which are part of the rare biosphere (i.e., opportunistic copiotrophic organisms). Second, we reveal the major role that macroorganisms may have on the dispersal and the geographic distribution of microbes. Third, we introduce an innovative and integrated view of the interactions between microbes and macroorganisms, namely sustaining the rares, which suggests that macroorganisms favor the maintenance of marine microbial diversity and are involved in the regulation of its richness and dynamics. Finally, we show how this hypothesis complements existing theories in microbial ecology and offers new perspectives about the importance of macroorganisms for the microbial biosphere, particularly the rare members

Where less may be more: how the rare biosphere pulls ecosystems strings

Rare species are increasingly recognized as crucial, yet vulnerable components of Earth’s ecosystems. This is also true for microbial communities, which are typically composed of a high number of relatively rare species. Recent studies have demonstrated that rare species can have an over-proportional role in biogeochemical cycles and may be a hidden driver of microbiome function. In this review, we provide an ecological overview of the rare microbial biosphere, including causes of rarity and the impacts of rare species on ecosystem functioning. We discuss how rare species can have a preponderant role for local biodiversity and species turnover with rarity potentially bound to phylogenetically conserved features. Rare microbes may therefore be overlooked keystone species regulating the functioning of host-associated, terrestrial and aquatic environments. We conclude this review with recommendations to guide scientists interested in investigating this rapidly emerging research area

Polyhydroxyalcanoates : une alternative ‘bio’ aux plastiques traditionnels

Ce numéro comprend les articles correspondant aux présentations du Colloque CIAg "Emballages alimentaires : innover pour la sécurité et la durabilité" organisé à Paris le 8 juin 2017.In recent years, the potential of biological routes to replace fossil fuel-based technologies in the drive towards sustainable production of chemicals and energy has been explored and demonstrated. Biodegradable polymers derived from renewable resources could contribute to the global production of plastics (more than 300 million tons per year) currently derived mainly from crude oil refining and, at the same time, reduce the environmental problems caused by plastic disposal by generating a closed carbon cycle. However, cost-effective designs are required if bioprocesses are to be competitive with oil-based equivalents.The polyhydroxyalkanoate (PHA) family consists of a large number of biodegradable polyesters produced by living organisms as carbon and energy reservoir. Short chain length PHAs, or scl-PHAs, are thermoplastics materials whereas medium chain length PHAs, mcl-PHA, are elastomers with good elongation properties that make them suitable for a wide range of applications, forbidden to scl-PHA. While technologies to produce scl-PHA, which most studied representative is PHB, are well known, studies on mcl-PHA are still at an early stage. Mcl–PHAs have been produced in pure culture from low cost materials using Psedudomonas species as biocatalysts. Studies in mixed microbial culture have revealed the possibility of obtaining mcl-PHAs when using a consortium of microorganisms. This strategy does not require costly sterilization operations and makes use of microorganisms’ capability to adapt to different environments and substrates. Enriching mcl-PHA storing bacteria and selecting operational conditions in the production stage that maximize the carbon flow towards mcl-PHA synthesis are essential to obtain processes with large outcomes. In this way, tailored made polyesters containing a stable range of scl and mcl-PHAs, or mcl-PHAs mixed with other natural polymers are environmentally friendly alternatives to conventional plastics and could contribute to the bio-economy developmentAu cours des dernières années, il a été démontré le potentiel des routes biologiques pour remplacer les combustibles fossiles comme ressource pour la production durable de produits chimiques et d'énergie. Ainsi, les polymères biodégradables dérivés de ressources renouvelables pourraient contribuer à la production mondiale de plastiques (plus de 300 millions de tonnes par an) provenant actuellement du pétrole et, en même temps, de réduire les problèmes environnementaux causés par l'élimination des matières plastiques. Cependant, une conception économiquement viable est nécessaire afin de développer des bioprocédés de production de bioplastiques compétitifs avec les équivalents pétroliers.La famille des polyhydroxyalcanoates (PHA) se compose d'un grand nombre de polyesters biodégradables produit par les organismes vivants comme réservoir de carbone et d'énergie. Les PHA à chaîne courte, ou les PHA-scl, sont des matériaux thermoplastiques alors que les PHA à longueur moyenne de chaîne, PHA-mcl, sont des élastomères présentant de bonnes propriétés d'élongation qui les rendent adaptés à une plus large gamme d’applications. Alors que les technologies pour produirePHA-scl, dont le représentant le plus étudié est PHB (polyhydroxybutyrate), sont bien connues, les études sur les PHA-mcl sont plus récentes. Les PHA-mcl ont été produits en culture pure à partir de matériaux à faible coût utilisant des espèces de Pseudomonas comme biocatalyseurs. Des études en culture microbienne mixte ont révélé également la possibilité d'obtenir des PHA-mcl par des consortia microbiens. Cette stratégie ne nécessite pas d'opérations coûteuses de stérilisation et utilise la capacité des microorganismes à s'adapter à différents environnements et substrats. L'enrichissement d’organismes producteurs de PHA-mcl et la sélection des conditions opérationnelles au stade de la production, afin de maximiser le flux de carbone vers la synthèse de la PHA-mcl sont essentiels pour obtenir des procédés efficients. De cette façon, les polyesters fabriqués sur mesure contenant une gamme stable de PHA-scl et PHA-mcl, ou de PHA-mcl mélangés à d'autres polymères naturels, sont des alternatives environnementales aux plastiques d’origine pétrochimique et peuvent contribuer au développent de la bioéconomie

Les micropolluants organiques contenus dans les produits résiduaires organiques ont-ils des impacts écotoxicologiques sur l’écosystème sol ?

National audienc

Fate and impact of the antibiotic ciprofloxacin in soils from integrated terrestrial microcosms submitted to pig slurry amendment

National audienc

Anaerobic lignocellulolytic microbial consortium derived from termite gut: enrichment, lignocellulose degradation and community dynamics

International audienceBackground: Lignocellulose is the most abundant renewable carbon resource that can be used for biofuels and commodity chemicals production. The ability of complex microbial communities present in natural environments that are specialized in biomass deconstruction can be exploited to develop lignocellulose bioconversion processes. Termites are among the most abundant insects on earth and play an important role in lignocellulose decomposition. Although their digestive microbiome is recognized as a potential reservoir of microorganisms producing lignocellulolytic enzymes, the potential to enrich and maintain the lignocellulolytic activity of microbial consortia derived from termite gut useful for lignocellulose biorefinery has not been assessed. Here, we assessed the possibility of enriching a microbial consortium from termite gut and maintaining its lignocellulose degradation ability in controlled anaerobic bioreactors. Results: We enriched a termite gut-derived consortium able to transform lignocellulose into carboxylates under anaerobic conditions. To assess the impact of substrate natural microbiome on the enrichment and the maintenance of termite gut microbiome, the enrichment process was performed using both sterilized and non-sterilized straw. The enrichment process was carried out in bioreactors operating under industrially relevant aseptic conditions. Two termite gut-derived microbial consortia were obtained from Nasutitermes ephratae by sequential batch culture on raw wheat straw as the sole carbon source. Analysis of substrate loss, carboxylate production and microbial diversity showed that regardless of the substrate sterility, the diversity of communities selected by the enrichment process strongly changed compared to that observed in the termite gut. Nevertheless, the community obtained on sterile straw displayed higher lignocellulose degradation capacity; it showed a high xylanase activity and an initial preference for hemicellulose. Conclusions: This study demonstrates that it is possible to enrich and maintain a microbial consortium derived from termite gut microbiome in controlled anaerobic bioreactors, producing useful carboxylates from raw biomass. Our results suggest that the microbial community is shaped both by the substrate and the conditions that prevail during enrichment. However, when aseptic conditions are applied, it is also affected by the biotic pressure exerted by microorganisms naturally present in the substrate and in the surrounding environment. Besides the efficient lignocellulolytic consortium enriched in this study, our results revealed high levels of xylanase activity that can now be further explored for enzyme identification and overexpression for biorefinery purposes