Carbon roadmap from syngas to polyhydroxyalkanoates in Rhodospirillum rubrum

The gasification of organic waste materials to synthesis gas (syngas), followed by microbial fermentation provides a significant resource for generating bioproducts such as polyhydroxyalkanoates (PHA). The anaerobic photosynthetic bacterium, Rhodospirillum rubrum, is an organism particularly attractive for the bioconversion of syngas into PHAs. In this study, a quantitative physiological analysis of R. rubrum was carried out by implementing GC-MS and HPLC techniques to unravel the metabolic pathway operating during syngas fermentation that leads to PHA production. Further, detailed investigations of the central carbon metabolites using 13C-labeled substrate showed significant CO2 assimilation (of 40 %) into cell material and PHA from syngas carbon fraction. By a combination of quantitative gene expression and enzyme activity analyses, the main role of carboxylases from the central carbon metabolism in CO2 assimilation was shown, where the Calvin Benson-Bassham Cycle (CBB) played a minor role. This knowledge sheds light about the biochemical pathways that contribute to synthesis of PHA during syngas fermentation being valuable information to further optimize the fermentation process.This work has been funded by the EU project SYNPOL (grant agreement n° 311815) under the European Union’s Seventh Framework Programme.Peer reviewe

Connectivity in times of control: writing/undoing/unpacking/acting out power performances.

In this collectively written article, the authors interrogate contemporary power constellations that run between control and connectivity. Regimes of individualism, hierarchies of assumed classifications and imperialistic subjectivities sustain the basis for political control that organises connections and divisions used to justify hierarchical dominations and distributions. This makes anti-oppression practices that value differing forms of connectivity and intra-dependence (between humans, more than humans, disciplines, all things considered to be of different bodies) nearly unimaginable. The authors offer/reconfigure/understand connectivity as a practice acting in and at odds with those controlling political regimes that organise and classify matter(s), while experimenting with their own writing methodology aimed at staying connected. Informed by new materialist feminist practices and ideas, the authors discuss the political stakes of multiple ideas of connectivity within three empirical scenarios: academic labour practices, social media and a digitally established mutual aid community. We trace entangled forces of separation and control shaped by global imperialism, processes of individuation and technological apparatuses and how they perform within these scenarios. This approach is mirrored in our practice of writing together. In an alternative to traditionalised ways of writing, we expand upon an embodied praxis, elaborating on multiple engagements while offering our own connections with these differing situated knowledges. In light of this, the authors write in a diffractive, collective fashion that lies somewhere between a conversation and the strict linearity of typical narratives.</div

Syngas obtained by microwave pyrolysis of household wastes as feedstock for polyhydroxyalkanoate production in Rhodospirillum rubrum

The massive production of urban and agricultural wastes has promoted a clear need for alternative processes of disposal and waste management. The potential use of municipal solid wastes (MSW) as feedstock for the production of polyhydroxyalkanoates (PHA) by a process known as syngas fermentation is considered herein as an attractive bio-economic strategy to reduce these wastes. In this work, we have evaluated the potential of Rhodospirillum rubrum as microbial cell factory for the synthesis of PHA from syngas produced by microwave pyrolysis of the MSW organic fraction from a European city (Seville). Growth rate, uptake rate, biomass yield and PHA production from syngas in R. rubrum have been analysed. The results revealed the strong robustness of this syngas fermentation where the purity of the syngas is not a critical constraint for PHA production. Microwave-induced pyrolysis is a tangible alternative to standard pyrolysis, because it can reduce cost in terms of energy and time as well as increase syngas production, providing a satisfactory PHA yield.Research leading to these results has received funding from the European Union's Seventh Framework Programme for Research, Technological Development and Demonstration under grant agreement no. 311815 (SYNPOL), and from the Comunidad de Madrid (P2013/MIT2807). D. B. also acknowledges the financial support received from PCTI and FICYT of the Government of the Principado de Asturias.Peer reviewe

Caracterización de las rutas de catabolismo de L-Lisina en Pseudomonas putida KT2440

Tesis Univ. Granada. Departamento de Bioquímica y Biología Molecular. Leída el 5 de julio de 200

Teaching Gender: Feminist Pedagogies and Responsibility in Times of Political Crisis

At Gender AssociationJuan de la Cierva (Universitat de Barcelona

Connectivity in times of control: writing/undoing/unpacking/acting out power performances

In this collectively written article, the authors interrogate contemporary power constellations that run between control and connectivity. Regimes of individualism, hierarchies of assumed classifications and imperialistic subjectivities sustain the basis for political control that organises connections and divisions used to justify hierarchical dominations and distributions. This makes anti-oppression practices that value differing forms of connectivity and intra-dependence (between humans, more than humans, disciplines, all things considered to be of different bodies) nearly unimaginable. The authors offer/reconfigure/understand connectivity as a practice acting in and at odds with those controlling political regimes that organise and classify matter(s), while experimenting with their own writing methodology aimed at staying connected. Informed by new materialist feminist practices and ideas, the authors discuss the political stakes of multiple ideas of connectivity within three empirical scenarios: academic labour practices, social media and a digitally established mutual aid community. We trace entangled forces of separation and control shaped by global imperialism, processes of individuation and technological apparatuses and how they perform within these scenarios. This approach is mirrored in our practice of writing together. In an alternative to traditionalised ways of writing, we expand upon an embodied praxis, elaborating on multiple engagements while offering our own connections with these differing situated knowledges. In light of this, the authors write in a diffractive, collective fashion that lies somewhere between a conversation and the strict linearity of typical narratives

Identification of the Initial Steps in d-Lysine Catabolism in Pseudomonas putida

Pseudomonas putida uses l-lysine as the sole carbon and nitrogen source which preferentially requires its metabolism through two parallel pathways. In one of the pathways δ-aminovalerate is the key metabolite, whereas in the other l-lysine is racemized to d-lysine, and l-pipecolate and α-aminoadipate are the key metabolites. All the genes and enzymes involved in the d-lysine pathway, except for those involved in the conversion of d-lysine into Δ(1)-piperideine-2-carboxylate, have been identified previously (30). In this study we report that the conversion of d-lysine into Δ(1)-piperideine-2-carboxylate can be mediated by a d-lysine aminotransferase (PP3590) and a d-lysine dehydrogenase (PP3596). From a physiological point of view PP3596 plays a major role in the catabolism of d-lysine since its inactivation leads to a marked reduction in the growth rate with l- or d-lysine as the sole carbon and nitrogen source, whereas inactivation of PP3590 leads only to slowed growth. The gene encoding PP3590, called here amaC, forms an operon with dpkA, the gene encoding the enzyme involved in conversion of Δ(1)-piperideine-2-carboxylate to l-pipecolate in the d-lysine catabolic pathway. The gene encoding PP3596, called here amaD, is the fifth gene in an operon made up of seven open reading frames (ORFs) encoding PP3592 through PP3597. The dpkA amaC operon was transcribed divergently from the operon ORF3592 to ORF3597. Both promoters were mapped by primer extension analysis, which showed that the divergent −35 hexamers of these operon promoters were adjacent to each other. Transcription of both operons was induced in response to l- or d-lysine in the culture medium

Syngas fermentation for polyhydroxyalkanoate production in Rhodospirillum rubrum

Bioconversion of organic waste into value-added products by a process called syngas fermentation is gaining considerable interest during the last years. Syngas is a gaseous mixture composed mainly of hydrogen and carbon monoxide and smaller quantities of other gases like CO2 that can be fermented by Rhodospirillum rubrum, a natural producer of polyhydroxybutyrate (PHB). R. rubrum is a highly versatile, purple, non-sulfur bacterium that can grow in a broad range of anaerobic and aerobic conditions. In anaerobiosis, it can utilize CO as carbon and energy source in the presence or absence of light. When exposed to CO, CO dehydrogenase, which catalyzes oxidation of CO into CO2, is induced. Part of the CO2 produced is assimilated into cell material and the remaining CO2, along with the H2, is released into the environment. The protocol below provides detailed information of PHB production during syngas fermentation by R. rubrum at lab scale.The design of this protocol was supported by the project European Commission SYNPOL no. 311815 [http:\crwww.sympol.org].Peer reviewe