RESUMEN
Recent efforts to combat increasing greenhouse gas emissions include their capture into advanced biofuels, such as butanol. Traditionally, biobutanol research has been centered solely on its generation from sugars. Our results show partial re-assimilation of CO2 and H2 by n-butanol-producer C. beijerinckii. This was detected as synchronous CO2/H2 oscillations by direct (real-time) monitoring of their fermentation gasses. Additional functional analysis demonstrated increased total carbon recovery above heterotrophic values associated to mixotrophic assimilation of synthesis gas (H2, CO2 and CO). This was further confirmed using 13C-Tracer experiments feeding 13CO2 and measuring the resulting labeled products. Genome- and transcriptome-wide analysis revealed transcription of key C-1 capture and additional energy conservation genes, including partial Wood-Ljungdahl and complete reversed pyruvate ferredoxin oxidoreductase / pyruvate-formate-lyase-dependent (rPFOR/Pfl) pathways. Therefore, this report provides direct genetic and physiological evidences of mixotrophic inorganic carbon-capture by C. beijerinckii.
Asunto(s)
1-Butanol/metabolismo , Carbono/metabolismo , Clostridium beijerinckii/metabolismo , Dióxido de Carbono/metabolismo , Isótopos de Carbono , Clostridium beijerinckii/genética , Clostridium beijerinckii/crecimiento & desarrollo , Electrones , Metabolismo Energético , Fermentación , Perfilación de la Expresión Génica , Genes Bacterianos , Hidrógeno/metabolismo , Cinética , Espectroscopía de Resonancia Magnética , Modelos Biológicos , Nitritos/metabolismo , Factores de Tiempo , Transcripción Genética , Transcriptoma/genéticaRESUMEN
Male canaries (Serinus canaria) produce most of their song syllable types on the left side of the syrinx, the two-sided vocal organ. Female canaries treated with testosterone propionate begin to sing in a male fashion, a behavior seldom seen in untreated females. To learn whether syringeal dominance occurs in testosterone-treated female canaries, we deactivated either the right or the left side of the syrinx by severing the tracheosyringeal nerve on that side. Recordings of the birds' songs were made before and after the nerve cut, and song analysis was based upon visual comparisons of sound spectrograms. Pre- and post-operative syllable types were identified by their frequency structures and repetition rates. Six of eight birds displayed clear left dominance as assessed by nerve cuts; therefore, we concluded that most, but not all, female canaries generate the majority of their syllable types with the left syrinx.