Methanosarcina barkeri

About: Methanosarcina barkeri is a research topic. Over the lifetime, 703 publications have been published within this topic receiving 32151 citations.

Total synthesis of the methanogenic cofactors methanofuran and methanofuran b

Abstract: Methanofuran, 3-{p-[(N-(N''((4R,5S)- or (4S,5R)-4,5,7-tricarboxyheptanoyl)-γ-L-glutamyl-γ-L-glutamyl)-β-amino)ethyl]phenoxymethyl}-5-(aminomethyl)furan, and methanofuran b, 3-{p-[N-(γ-L-glutamyl-γ-L-glutamyl-γ-L-glutamyl)-β-amino)ethyl]phenoxymethyl}-5-(aminomethyl)furan, are the first cofactors involved in the convertion of carbon dioxide to methane by the methanogenic bacteria Methanobacterium thermoautotriphicum and Methanosarcina barkeri, respectively. There two cofactors have now been synthesized, starting from glutamic acid, dimethyl glutarate, methyl 5-formyl-3-furoate, and tyramine. The synthetic compounds give the name NMR and mans spectra and biological activities an the natural cofactors

Membranes of thermophiles and other extremophiles

Abstract: Publisher Summary This chapter discusses an overview of different methods for the isolation of lipids from extremophilic organism. Different methods are discussed for the isolation of ether lipids from Archaea and ester lipids from bacteria. Furthermore, a protocol is provided for the preparation of liposomes from the isolated lipids and the methodology is described to employ these liposomes for proton permeability assays. The isolation of lipid relies on the treatment of freeze-dried cell material with organic solvents that extract lipids from the membranes. The methods for isolation of ether and ester lipids differ. With ether lipids, a more rigorous Soxhlet extraction is employed, which involves a lengthy extraction protocol in which the material is heated in organic solvent. This method is used to isolate the polar lipid fractions of a variety of archaeal species, such as the hyperthermophiles Sulfolobus acidocaldarius, S. solfataricus, Pyrococcus furiosus, and also from the mesophile Methanosarcina barkeri. To analyze the functional properties of the lipids, lipid vesicles are formed by hydration of the lipids into an aqueous buffer.

Different outer membrane c ‐type cytochromes are involved in direct interspecies electron transfer to Geobacter or Methanosarcina species

Abstract: Direct interspecies electron transfer (DIET) may be most important in methanogenic environments, but mechanistic studies of DIET to date have primarily focused on cocultures in which fumarate was the terminal electron acceptor. To better understand DIET with methanogens, the transcriptome of Geobacter metallireducens during DIET-based growth with G. sulfurreducens reducing fumarate was compared with G. metallireducens grown in coculture with diverse Methanosarcina. The transcriptome of G. metallireducens cocultured with G. sulfurreducens was significantly different from those with Methanosarcina. Furthermore, the transcriptome of G. metallireducens grown with Methanosarcina barkeri, which lacks outer-surface c-type cytochromes, differed from those of G. metallireducens cocultured with M. acetivorans or M. subterranea, which have an outer-surface c-type cytochrome that serves as an electrical connect for DIET. Differences in G. metallireducens expression patterns for genes involved in extracellular electron transfer were particularly notable. Cocultures with c-type cytochrome deletion mutant strains, ∆Gmet_0930, ∆Gmet_0557 and ∆Gmet_2896, never became established with G. sulfurreducens but adapted to grow with all three Methanosarcina. Two porin–cytochrome complexes, PccF and PccG, were important for DIET; however, PccG was more important for growth with Methanosarcina. Unlike cocultures with G. sulfurreducens and M. acetivorans, electrically conductive pili were not needed for growth with M. barkeri. Shewanella oneidensis, another electroactive microbe with abundant outer-surface c-type cytochromes, did not grow via DIET. The results demonstrate that the presence of outer-surface c-type cytochromes does not necessarily confer the capacity for DIET and emphasize the impact of the electron-accepting partner on the physiology of the electron-donating DIET partner.

Self-replicating Biophotoelectrochemistry System for Sustainable CO Methanation.

Abstract: Efficient conversion of CO-rich gas to methane (CH4) provides an effective energy solution by taking advantage of existing natural gas infrastructures. However, traditional chemical and biological conversions face different challenges. Herein, an innovative biophotoelectrochemistry (BPEC) system using Methanosarcina barkeri-CdS as a biohybrid catalyst was successfully employed for CO methanation. Compared with CO2-fed BPEC, BPEC-CO significantly extended the CH4 producing time by 1.7-fold and exhibited a higher CH4 yield by 9.5-fold under light irradiation. This superior conversion of CO resulted from the fact that CO could serve as an effective quencher of reactive species along with the photoelectron production. In addition, CO was used as a carbon source either directly or indirectly via the produced CO2 for M. barkeri. Such a process improved the redox activities of membrane-bound proteins for BPEC methanogenesis. These results were consistent with the transcriptomic analyses, in which the genes for the putative CO oxidation and CO2 reduction pathways in M. barkeri were highly expressed, while the gene expression for reactive oxygen species detoxification remained relatively stable under light irradiation. This study has provided the first proof-of-concept evidence for sustainable CO methanation under a mild condition in the self-replicating BPEC system.

Effect of some physical and chemical parameters on the fermentation of cellulose to methane by a coculture system

Abstract: In the fermentation of cellulose to methane by the triculture of Acetivibrio cellulolyticus – Desulfovibrio sp. – Methanosarcina barkeri, methanogenesis was the rate-limiting step. The optimal temperature was 35 °C. In the presence of initially added hydrogen, initiation of cellulose hydrolysis was delayed until most of the hydrogen was metabolized, and then the fermentation which followed was comparable with the N2: CO2 control. Increased CH4 yields and rates of formation were stoichiometrically related to the utilization of the hydrogen initially present. Added acetate had no effect on cellulolysis. The increased yields of CH4 observed could be accounted for by utilization of the added acetate. When Methanobrevibacter sp. was included in the coculture (without added H2 or acetate), no hydrogen accumulated and lower rates of acetate utilization and subsequent CH4 evolution were observed. These results suggest a requirement for hydrogen by M. barkeri for efficient acetate utilization. Controlling the pH a...