Pathways and bioenergetics of anaerobic carbon monoxide fermentation

Carbon monoxide can act as a substrate for different modes of fermentative anaerobic metabolism. The trait of utilizing CO is spread among a diverse group of microorganisms, including members of bacteria as well as archaea. Over the last decade this metabolism has gained interest due to the potential of converting CO-rich gas, such as synthesis gas, into bio-based products. Three main types of fermentative CO metabolism can be distinguished: hydrogenogenesis, methanogenesis, and acetogenesis, generating hydrogen, methane and acetate, respectively. Here, we review the current knowledge on these three variants of microbial CO metabolism with an emphasis on the potential enzymatic routes and bio-energetics involved.The authors involved were financially supported by an ERC grant (project 323009) and the Gravitation grant (project 024.002.002) of the Netherlands Ministry of Education, Culture and Science and the Netherlands Science Foundation (NWO)

Anaerobic Decomposition of Switchgrass by Tropical Soil-Derived Feedstock-Adapted Consortia

Tropical forest soils decompose litter rapidly with frequent episodes of anoxic conditions, making it likely that bacteria using alternate terminal electron acceptors (TEAs) play a large role in decomposition. This makes these soils useful templates for improving biofuel production. To investigate how TEAs affect decomposition, we cultivated feedstock-adapted consortia (FACs) derived from two tropical forest soils collected from the ends of a rainfall gradient: organic matter-rich tropical cloud forest (CF) soils, which experience sustained low redox, and iron-rich tropical rain forest (RF) soils, which experience rapidly fluctuating redox. Communities were anaerobically passed through three transfers of 10 weeks each with switchgrass as a sole carbon (C) source; FACs were then amended with nitrate, sulfate, or iron oxide. C mineralization and cellulase activities were higher in CF-FACs than in RF-FACs. Pyrosequencing of the small-subunit rRNA revealed members of the Firmicutes, Bacteroidetes, and Alphaproteobacteria as dominant. RF- and CF-FAC communities were not different in microbial diversity or biomass. The RF-FACs, derived from fluctuating redox soils, were the most responsive to the addition of TEAs, while the CF-FACs were overall more efficient and productive, both on a per-gram switchgrass and a per-cell biomass basis. These results suggest that decomposing microbial communities in fluctuating redox environments are adapted to the presence of a diversity of TEAs and ready to take advantage of them. More importantly, these data highlight the role of local environmental conditions in shaping microbial community function that may be separate from phylogenetic structure

The woman-animal in the work of Graça Morais:an identification between fragility and visionary power

La femme-animal traverse l’oeuvre de Graça Morais depuis les années 80. Être hybride, à mi-chemin entre humain, animal, et parfois végétal ou surnaturel, elle semble dotée d’un pouvoir salvateur. Liée à la terre, garante de la mémoire, son pouvoir d’enfantement la rattache à l’avenir, lui conférant un don de prémonition. Graça Morais s’identifie souvent aux animaux de Trás-os-Montes, renforçant son lien avec sa terre natale. Cette femme-animal s’enracine dans le primitivisme surréaliste et l’anthropologie de Lévi-Strauss, actualisés par des artistes des années 60.The woman-animal has been recurring in Graça Morais’ work since the 1980s. A hybrid being, part human, part animal, and sometimes vegetal or supernatural, she appears endowed with a salvific power. Connected to the earth and a guardian of memory, her power of creation ties her to the future, giving her a gift of premonition. Graça Morais often identifies with the animals of Trás-os-Montes, reinforcing her bond with her homeland. This woman-animal is rooted in surrealist primitiv-ism and the anthropology of Lévi-Strauss, up-dated by artists of the 1960s.info:eu-repo/semantics/publishedVersio