"Microbial fuel cells show promise for conversion of organic wastes and renewable biomass to electricity, but further optimization is required for most applications," says Derek Lovley of the University of Massachusetts in Amherst. Earlier this month, Lovley announced at a meeting that he and his colleagues were able to achieve a 10-fold increase in electrical output by allowing the bacteria in microbial fuel cells to grow on biofilms on the electrodes of a fuel cell.
This week, Gemma Reguera, a researcher in Lovley’s lab will present data identifying for the first time how these bacteria are able to transfer electrons through the biofilms to the electrodes.
"Cells at a distance from the anode remained viable with no decrease in the efficiency of current production as the thickness of the biofilm increased. These results are surprising because Geobacter bacteria do not produce soluble molecules or ’shuttles’ that could diffuse through the biofilm and transfer electrons from cells onto the anode," says Reguera.
She and her colleagues discovered that the bacteria produce conductive protein filaments, or pili ’nanowires,’ to transfer electrons. The finding that pili can extend the distance over which electrons can be transferred suggests additional avenues for genetically engineering the bacteria to further enhance power production.
Researchers from the Universidad Nacional Autonoma de Mexico announce that they have genetically engineered the bacterium Bacillus subtilis to directly ferment glucose sugar to ethanol with a high (86%) yield. This is the first step in a quest to develop bacteria that can breakdown and ferment cellulose biomass directly to ethanol.
"Currently ethanol is produced primarily from sugarcane or cornstarch, but much more biomass in the whole plant, including stems and leaves, can be converted to ethanol using clean technology," says Aida-Romero Garcia, one of the researchers on the study. The next step is to engineer the bacteria to produce the enzymes, known as cellulases, to break the stems and leaves down into the simple carbohydrates for fermentation.
Bacteria can not only produce alternative fuels, but could also aid in oil production by boosting output of existing wells. Michael McInerney and his colleagues at the University of Oklahoma will present research demonstrating the technical feasibility of using detergent-producing microorganisms to recover entrapped oil from oil reservoirs.
"Our approach is to use microorganisms that make detergent-like molecules (biosurfactants) to clean oil off of rock surfaces and mobilize oil stuck in small cavities. However, up till now, it is not clear whether microorganisms injected into an oil reservoir will be active and whether they will make enough biosurfactant to mobilize entrapped oil," says McInerney.
He and his colleagues were able to inoculate an oil reservoir with specific strains of bacteria and have these bacteria make biosurfactants in amounts needed for substantial oil recovery.
"We now know that the microorganisms will work as intended in the oil reservoir. The next important question is whether our approach will recover entrapped oil economically. We saw an increase in oil production after our test, but we need to measure oil production more precisely to be certain," says McInerney.
Jim Sliwa | EurekAlert!
Rainbow colors reveal cell history: Uncovering β-cell heterogeneity
22.09.2017 | DFG-Forschungszentrum für Regenerative Therapien TU Dresden
The pyrenoid is a carbon-fixing liquid droplet
22.09.2017 | Max-Planck-Institut für Biochemie
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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