Methanosarcina barkeri

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

Estimation of Adhesion and Aggregation of Acetate-utilizing Methanogens

Abstract: From the view point of fine particle technology, the effects of surface properties of methanogens, which are related to the rate-limiting step in the methane fermentation process, on their adhesion and aggregation were examined. As a result, Methanosarcina barkeri were found to be charged negatively and their isoelectric point was around pH 2. In contrast, Methanosaeta concilii was found to be non-charged and their isoelectric point was around pH 4.5. According to the ATR-FTIR analysis and acid-base titration, it was guessed that the difference of surface potential between two types of methanogens was due to the difference of the amount of carboxyl group and phosphate group on their microbial surface. Methanosarcina barkeri showed better adhesion to not the negatively-charged glass but to the positively-charged one. Percent aggregate of Methanosarcina barkeri increased with an increase in the ionic strength of the cell suspension. In contrast, percent aggregate of Methanosaeta concilii was almost constant regardless of the ionic strength. These adhesion and aggregation phenomena could be understood by the electrostatic interaction and the change of free energy of interaction between methanogen and slide glass.

Adaptation of Methanosarcina barkeri 227 as acetate scavenger for succinate fermentation by Actinobacillus succinogenes.

Abstract: Acetate is the main by-product from microbial succinate production. In this study, we performed acetate removal by Methanosarcina barkeri 227 for succinate fermentation by Actinobacillus succinogenes 130Z. The acetoclastic methanogen M. barkeri requires similar environmental factors to A. succinogenes, and the conditions required for co-cultivation were optimized in this study: gas used for anaerobicization, strain adaptation, medium composition, pH adjustment, and inoculation time points. M. barkeri 227 was adapted to acetate for 150 days, which accelerated the acetate consumption to 9-fold (from 190 to 1726 mmol gDW−1 day−1). In the acetate-adapted strain, there was a noticeable increase in transcription of genes required for acetoclastic pathway—satP (acetate transporter), ackA (acetate kinase), cdhA (carbon monoxide dehydrogenase/acetyl-CoA synthase complex), and mtrH (methyl-H4STP:CoM methyltransferase), which was not induced before the adaptation process. The activities of two energy-consuming steps in the pathway—acetate uptake and acetate kinase—increased about 3-fold. This acetate-adapted M. barkeri could be successfully applied to succinate fermentation culture of A. succinogenes, but only after pH adjustment following completion of fermentation. This study suggests the utility of M. barkeri as an acetate scavenger during fermentation for further steps towards genetic and process engineering.

Kinetics of the methanogenic fermentation of acetate. [Methanosarcina barkeri]

Abstract: Inhibition of the fermentation of acetate to methane and carbon dioxide by acetate was analyzed with an acetate-acclimatized sludge and with Methanosarcina barkeri Fusaro under mesophilic conditions. A second-order substrate inhibition model, q{sub CH{sub 4}} = q{sub m}S/(K{sub s} + S + (S{sup 2}/K{sub i})), where S was the concentration of undissociated acetic acid, not ionized acetic acid, could be applicable in both cases. The analysis resulted in substrate saturation constants, K{sub s}, of 4.0 {mu}M for the acclimatized sludge and 104 {mu}M for M. barkeri. The threshold concentrations of undissociated acetic acid when no further acetate utilization was observed were 0.078 {mu}M (pH 7.50) for the acclimatized sludge and 4.43 {mu}M (pH 7.45) for M. barkeri. These kinetic results suggested that the concentration of undissociated acetic acid became a key factor governing the actual threshold acetate concentration for acetate utilization and that the acclimatized sludge in which Methanothrix spp. appeared dominant could utilize acetate better and survive at a lower concentration of undissociated acetic acid than could M. barkeri.

Compound bacterium capable of quickly removing propionic acid accumulation as well as preparation method and application of compound bacterium

Abstract: The invention provides a preparation method of a compound bacterium capable of quickly removing propionic acid accumulation. The preparation method comprises the following steps: (1) taking effluent of a dextranum wastewater anaerobic digester as an original inoculums, and sodium propionate as a carbon source, and performing inoculated culture till the degradation rate of propionic acid in a culture reaches 50-80% and the content of methane is 30-50%; (2) transferring the object obtained in the step (1) to a fresh culture medium for culture, and adding the following bacteria into every ml of a culture solution of the object obtained in the step (1): (2.5-5)*10 Pelotomaculum schinkii, (1-2.5)*10 Pelotomaculum propionicicum, (1-3)*10 Syntrophobacter wolinii, (0.4-1.4)*10 Methanospirillum hungatei, (0.5-1.4)*10 Methanoculleus palmolei, (0.5-1.4)*10 Methanoculleus bourgensis, (0.5-2.5)*10 Methanosarcina barkeri and (1-3)*10 Methanosarcina mazei; (3) performing airtight culture on the object obtained in the step (2) to obtain the compound bacterium capable of quickly removing propionic acid accumulation. The invention further provides application of the compound bacterium to the anaerobic digestion technology, particularly to biogas fermentation. The compound bacterium can quickly and efficiently remove propionic acid accumulation, and greatly improve the anaerobic digestion efficiency and stability.