— Climate sensitivity to CO2 more limited than extreme projections — A new study suggests that the rate of global warming from doubling of atmospheric carbon dioxide may be less than the most dire estimates of some previous studies - and, in fact, may…
— Saving Da Vinci's Last Supper from air pollution — Having survived long centuries, political upheaval, and even bombings during World War II, Leonardo Da Vinci's masterpiece Last Supper now faces the risk of damage from air pollution…
— After 25 years, sustainability is a growing science that's here to stay — Sustainability has not only become a science in the past 25 years, but it is one that continues to be fast-growing with widespread international collaboration, broad disciplinary composition…
— Markets drive conservation in Central Africa — Certification has shown that commercial forestry can co-exist with conservation objectives in the Congo Basin, according to conclusions reached at an international seminar 'Forest management…
— Great Plains river basins threatened by pumping of aquifers — Suitable habitat for native fishes in many Great Plains streams has been significantly reduced by the pumping of groundwater from the High Plains aquifer - and scientists analysing…
— Rivers may aid climate control in cities — Speaking at the URSULA (Urban River Corridors and Sustainable Living Agendas) Conference, in Sheffield, Dr Abigail Hathway, of the University of Sheffield, will demonstrate how rivers…
— Vultures dying at alarming rate — Vultures in South Asia were on the brink of extinction until Lindsay Oaks and Richard Watson, from The Peregrine Fund in the US, undertook observational and forensic studies to find…
— Predicting future threats for global amphibian biodiversity — Amphibian populations are declining worldwide, and their declines far exceed those of other animal groups: more than 30% of all species are listed as threatened according to the Red…
— Study shows deforestation causes cooling — Deforestation, considered by scientists to contribute significantly to global warming, has been shown by a Yale-led team to actually cool the local climate in northern latitudes, according…
Blocking carbon dioxide fixation in bacteria increases biofuel production
Reducing the ability of certain bacteria to fix carbon dioxide can greatly increase their production of hydrogen gas that can be used as a biofuel. Researchers from the University of Washington, Seattle, report their findings in the current issue of online journal mBio(R).
'Hydrogen gas is a promising transportation fuel that can be used in hydrogen fuel cells to generate an electric current with water as the only waste product,' says Caroline Harwood, who conducted the study with James McKinlay. 'Phototrophic bacteria, like Rhodopseudomonas palustris obtain energy from light and carbon from organic compounds during anaerobic growth. Cells can naturally produce hydrogen gas biofuel as a way of disposing of excess electrons.'
Feeding these bacteria more electron rich organic compounds though, does not always produce the logically expected result of increased hydrogen production. Harwood and McKinlay analysed metabolic functions of R. palustris grown on four different compounds to better understand what other variables might be involved.
One factor involved appears to be the Calvin cycle, a series of biochemical reactions responsible for the process known as carbon dioxide fixation. The Calvin cycle converts carbon dioxide and electrons into organic compounds. Therefore carbon dioxide-fixation and hydrogen production naturally compete for electrons.
When they tested a strain of the bacterium, which had been genetically modified to block carbon dioxide-fixation they observed an increased output of hydrogen from all four substrates.
The Calvin cycle was not the only variable affecting hydrogen production that Harwood and McKinlay identified in the paper. They also determined that the metabolic route a growth substrate took on its way to becoming a building block for making new cells also played a role.
'Our work illustrates how an understanding of bacterial metabolism and physiology can be applied to engineer microbes for the production of sustainable biofuels,' says Harwood.
Or subscribe for our Newsletter, a free e-mail publication. It is published practically every day.
Keeping cool using the summer heat
New data show much of Antarctica is warming more than previously thought
What is powering your Christmas lights?
Saving water key to reducing energy use