Methanogen

Event Date: 
Wednesday, January 28, 2015 - 18:00 - 18:15
Institution: 
University of New South Wales
Title: 

Biomining and methanogenesis for resource extraction from asteroids

Abstract: 

As spacecraft fuel is a limited resource, creating a readily available source for hydrocarbon-based fuels in space will reduce launch cost and increase operating time of spacecraft. Biomethanation is viable for Earth-based operations, thus applications in space under controlled conditions have potential. This study proposes a sustainable environment for methanogens on Near-Earth Objects. Vacuum and desiccation effects, at 0.025% Earth atmospheric pressure, are conducted on three bacterial and three Archaea strains to test post-exposure viability. Cell degradation and colony size reduction was quantified for aerobic strains. Adverse effects were exhibited more so in gram-negative than gram-positive strains. Archaea showed limited to no cell degradation, providing evidence that vacuum effects, at these pressures, will have minor effects on in-situ biofuel operations. If successful, a sustainable and cost-effective method of metal extraction and producing methane based fuel reservoirs could revolutionise in-situ resource and fuel resupply of spacecraft, thus enhancing spacefaring capabilities.

 

In September, JAMS was back into top gear, with a bigger audience, and a room with a view. Kent Lim from Macquarie University led off with a talk on his PhD work on the biocontrol agent Pseudomonas strain Pf5. As is often the case in science, things didn’t work out as expected, and Kent found that knocking out suspected pyochelin transporters led to an increase rather than a decrease in efflux of this siderophore and its metabolic precursors. Kent valiantly soldiered on, applying qRT-PCR and Biolog phenotype microarrays to untangle the problem, but unfortunately, this released even more worms from the seemingly-bottomless can provided by strain Pf5. It seems that these transporters may in fact also be regulatory proteins, explaining the unexpected pleiotropic effects of the knockouts.
 

Event Date: 
Wednesday, September 26, 2012 - 19:00 - 20:00
Institution: 
University of New South Wales
Title: 

Microbial methane formation and oxidation in abandoned coal mines

Abstract: 

 
Worldwide, mine gas is being used increasingly for heat and power production. About 7% of the annual methane emissions originate from coal mining. In abandoned coal mines, stable carbon and hydrogen isotopic signatures of methane indicate a mixed thermogenic and biogenic origin. The thermogenic methane is a reminder of geological processes, but its biogenic formation is still going on. Besides hard coal, possible sources for methane are large amounts of mine timber left behind after the end of mining.
Methanogenic archaea are responsible for the production of substantial amounts of methane. Mine timber and hard coal showed an in situ production of methane with isotopic signatures similar to those of the methane in the mine atmosphere. Long-term incubations of coal and timber as sole carbon sources formed methane over a period of 9 months. We directly unraveled the active methanogens mediating the methane release as well as the active bacteria potentially involved in the trophic network. Furthermore, we proved the presence of an active methanotrophic community. Directed by the methane production and oxidation, respectively, samples for DNA stable-isotope probing (SIP) coupled to subsequent quantitative PCR and DGGE analyses were taken from long term incubations over 6 months. The stable-isotope-labeled precursors of methane, [13C]acetate and H2-13CO2, and 13CH4 were fed to liquid cultures from hard coal and mine timber. Predominantly acetoclastic methanogenesis was stimulated in enrichments containing acetate and H2+CO2. The H2+CO2 was mainly used by acetogens similar to Pelobacter acetylenicus and Clostridium species forming acetate as intermediate and providing it to the methanogens. Active methanogens, closely affiliated to Methanosarcina barkeri, utilized the readily available acetate rather than the thermodynamical more favourable hydrogen. Furthermore, the activity of a distinct methane-oxidizing community is predominated of a member belonging to the type I methanotrophs similar to Methylobacter marinus that assimilated 13CH4 nearly exclusively. Thus, active methanotrophic bacteria are associated with the methanogenic microbial community that is highly adapted to the low H2 conditions found in the coal mines with acetate as the main precursor of the biogenic methane.

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