Hyperthermophilic methanogenic archaea act as high-pressure CH4 cell factories

Abstract

Bioprocesses converting carbon dioxide with molecular hydrogen to methane (CH4) are currently being developed to enable a transition to a renewable energy production system. In this study, we present a comprehensive physiological and biotechnological examination of 80 methanogenic archaea (methanogens) quantifying growth and CH4 production kinetics at hyperbaric pressures up to 50 bar with regard to media, macro-, and micro-nutrient supply, specific genomic features, and cell envelope architecture. Our analysis aimed to systematically prioritize high-pressure and high-performance methanogens. We found that the hyperthermophilic methanococci Methanotorris igneus and Methanocaldococcoccus jannaschii are high-pressure CH4 cell factories. Furthermore, our analysis revealed that high-performance methanogens are covered with an S-layer, and that they harbour the amino acid motif Tyrα444 Glyα445 Tyrα446 in the alpha subunit of the methyl-coenzyme M reductase. Thus, high-pressure biological CH4 production in pure culture could provide a purposeful route for the transition to a carbon-neutral bioenergy sector.

The Historical Development of Cultivation Techniques for Methanogens and Other Strict Anaerobes and Their Application in Modern Microbiology

“…Recently, 80 methanogens were grown in 22 chemically defined and/or complex media to assess their methane production and growth characteristics for the identification of high-performance methanogens. The analysis also included multivariate statistical analysis of the medium's constituents [8]. 1 dissolve NTA in 500 ml water and adjust pH to 6.5 with KOH, then add the rest of the compounds.…”

“…Vitamin requirements differ among species. Many methanogens can be grown without the addition of vitamins [8,56,70,71], but previous studies have reported that the presence of vitamins supports their growth [72,73]. Other species might be fastidious and require a whole range of different vitamins, e.g., Methanimicrococcus blatticola [72,74,75].…”

“…There are a number of different indicators with resazurin being the most commonly used [76]. However, when methanogens are frequently cultivated in the laboratory, redox indicators are not applied any more [8,64].…”

“…The first efforts began more than a century ago and continued until the present variety of anaerobic cultivation methods and procedures was established [2][3][4][5]. For the most common anaerobic and aerotolerant microorganisms, cultivation techniques are often manageable under ordinary laboratory conditions, but more sophisticated cultivation methods are required for the study of strictly anaerobic microorganisms, such as methanogens, whose importance and biotechnological applications are now of utmost interest [6][7][8][9].…”

Comparison and Gas Loading Impact on Counter- and Concurrent Trickle-Bed Reactor Configurations for Ex-Situ Biomethanation

“…It increased from 4.9-24.8% in counter-current TBR while from 0.1-21.6% in concurrent con guration. It can be hypothesized that late Methanothermobacter development was correlated to its potential slower growth rate compared to Methanonobacterium or due to the applied high gas loading rates 30 .…”