Wireless Sensor Networks: 5th European Conference, EWSN 2008, Bologna, Italy, January 30-February 1, 2008, Proceedings


Produit DescriptionThis book constitutes the procedure arbitrated from 5 º Atelier European on the Networks of sensors inal

Wireless Sensor Networks: 6th European Conference, EWSN 2009 Cork, Ireland, February 11-13, 2009, Proceedings


This book constitutes the refereed proceedings of the 6th European Conference on Wireless Sensor Networks, EWSN 2009, held in Cork, Ireland, in Februar 2009. The 23 revised full papers presented were carefully reviewed and selected from 145 submissions. The papers are organized in topical sections on performance and quality of service, routing, coordination and synchronisation, data collection, security, as well as evaluation and management.
Wireless Sensor Networks: 6th European Conference, EWSN 2009 Cork, Ireland, February 11-13, 2009, Proceedings

Bacteria That Release Oil as They Grow

Bacteria That Release Oil as They Grow

Xinyao Liu and Professor Roy Curtiss at Arizona State University’s Biodesign Institute have coaxed photosynthetic microbes to secrete oil so bypassing energy and cost barriers that have hampered green biofuel production.  The results appeared March 29,2010 in the advanced online issue of the Proceedings of the National Academy of Sciences.

The results are the latest of a series of adaptations pioneered by Liu.  The opening was the use of modified thioesterases to cause secretion of fatty acids first described for Escherichia coli by John Cronan of the University of Illinois more than a decade ago. Liu takes off from there.  Liu realized that if cyanobacteria could be cajoled into overproducing fatty acids, their accumulation within the cells would eventually cause these fatty acids to leak out through the cell membrane, through the process of diffusion. To accomplish this, Liu introduced a specific enzyme, known as thioesterase, into cyanobacteria.

Photosynthetic Cyanobacteria. rmation.

The enzyme is able to uncouple fatty acids from complex carrier proteins, freeing them within the cell where they accumulate, until the cell secretes them.  Liu explains, “I use genes that can steal fatty acids from the lipid synthesis pathway.”  The thioesterase acts to efficiently clip the bonds associating the fatty acids with more complex molecules.

A second series of modifications enhances the secretion process, by genetically deleting or modifying two key layers of the cellular envelope known as the S and peptidoglycan layers, thus allowing fatty acids to more easily escape outside the cell, where their low water solubility causes them to precipitate out of solution, forming a whitish residue on the surface that would be available for collection. Study results show a 3-fold increase in fatty acid yield, after genetic modification of the two membrane layers.

To improve the fatty acid production even further, the group working with Liu added genes to cause overproduction of fatty acid precursors and removed some cellular pathways that were non-essential to the survival of cyanobacteria. Such modifications ensure that the microbe’s resources are devoted to basic survival and lipid production.

Liu emphasizes that the current research has moved along at a lightening clip, with only about 6 months passing from the initial work, through production of the first strains.  He attributes the facts to the formidable expertise in the area of microbial genetic manipulation of his assisting working group, assembled at the Biodesign Institute. “I don’t think any group would have the capacity to do this as fast,” he said.

Professor Curtiss agrees, noting that “the seminal advance has been to combine a number of genetic modifications and enzyme activities previously described in other bacteria and in plants in the engineered cyanobacteria strains along with the introduction of newly discovered modifications to increase production and secretion of fatty acids. The results to date are encouraging and we are confident of making further improvements to achieve enhanced productivity in strains currently under construction and development. In addition, optimizing growth conditions associated with scale-up will also improve productivity.”  These are high potential assertions – especially as the bacteria at issue are photosynthetic.

Professor Curtiss who is director of the Biodesign Institute’s Center for Infectious Diseases and Vaccinology and professor in the School of Life Sciences also said, “By releasing their precious cargo outside the cell, we have optimized bacterial metabolic engineering to develop a truly green route to biofuel production.”  Curtiss reminds us, “The real costs involved in any biofuel production are harvesting the fuel precursors and turning them into fuel.”  Harvesting is a matter that still bedevils algae research in particular and other pathways to a lesser or greater extent.

Saving the life, be it bacteria or algae is highly worthwhile from a cost and process perspective.  Its worth repeating Liu’s quote from the press release.  “In China, we have a saying,” Liu says. “We don’t kill the hen to get the eggs.”

The success in this is rather than destroying the cyanobacteria, the group has ingeniously reengineered their genetics, producing mutant strains that continuously secrete fatty acids through their cell walls. The cyanobacteria essentially act like tiny biofuel production facilities.

This is quite a feat all by its self.  Now it’s on to scaling up and steps involved to cultivate the organisms.  Missing some cell wall as noted might prove a new problem.  One way is in hand now.  It will be quite something if it gets into mass production. One wonders what other researchers have working.

One senses that some competition is coming.  The more the better.


The original is here: New Energy and Fuel

Fuel From the Gribble

From examining the genes expressed in the guts of the gribble, researchers have demonstrated that a gribble’s digestive system contains enzymes that could hold the key to converting wood and straw into liquid biofuels.  Yes, there is such a creature called the gribble, it’s a really small crustacean scientifically named Limnoria quadripunctata.

The Gribble aka Limnoria quadripunctata. rmation.

Since the dawn of going to sea in wooden ships seafarers have been plagued by wood-eating gribble that destroyed the ships, and these creatures continue to wreak damage on wooden piers and docks in coastal communities worldwide.

A research team headed by Professor Simon McQueen-Mason of the Centre for Novel Agricultural Products in the Department of Biology and Professor Neil Bruce at York University, and Dr Simon Cragg at Portsmouth University reveal that the gribble’s digestive tract is dominated by enzymes that attack the polymers that make up wood.  The research is published in the March 23, 2010 issue of the Proceedings of the National Academy of Science.

The gribble’s claim to fame is its digestive tract holds one of the most abundant cellulose degrading enzymes, which have never been seen before in animals.  Unlike termites and other wood-eating animals, the gribbles have no helpful microbes in their digestive system. This means that they must possess all of the enzymes needed to convert wood into sugars within themselves.

Professor McQueen-Mason explains the research activity, “Most animals that consume wood have digestive tracts packed with microbes that help to digest the cell wall polymers, but the gribble’s is sterile, so it must produce all the enzymes needed to break down the wood itself. We have done extensive DNA sequencing of the genes expressed in its gut, and we have detected cellulases never seen in animals before. We want to see if it’s possible to adapt the gribble digestive enzymes for industrial purposes.”

The scientists at York are now studying the enzymes to establish how they work, and whether they can be adapted to industrial applications. The press release suggests “Perhaps one day soon seafarers will be sailing the seas on ships powered with biofuels produced with gribble enzymes.”

Professor McQueen-Mason said, “This may provide clues as to how this conversion could be performed in an industrial setting.”

The research is backed by the BBSRC Sustainable Bioenergy Centre, a £26M research investment by the Biotechnology and Biological Sciences Research Council and has six research programs at universities and research institutes.

Duncan Eggar, BBSRC Bioenergy Champion, said, “The world needs to quickly reduce its dependence on fossil fuels and sustainably produced bioenergy offers the potential to rapidly introduce liquid transport fuels into our current energy mix.”

The team has already zeroed in onglycosyl hydrolase genes and found hemocyanin transcripts were highly abundant in the hepatopancreas transcriptome. Based on recent studies indicating that these proteins may function as phenoloxidases in isopods, the paper discusses a possible role for hemocyanins in lignin decomposition.  There might be the key.

This research is just back from the very sharp edge of research.  Yet the realization those crustaceans have enzyme chemistry that may be useful is a very intuitive thought.  How the biochemistry might have a role is yet to be seen.  But coastal folks know these critters can certainly eat away wood that’s laced with all sorts of inhibitors from creosote to arsenic compounds.  The things these enzymes might take apart might be an incredibly large list.

This just might be an early look at a breakthrough.


Original post here: New Energy and Fuel