Microbes could soon be used to convert metallic wastes into high-value catalysts for generating clean energy, say scientists from the School of Biosciences at the University of Birmingham, who have discovered the mechanisms that allow the common soil bacterium Desulfovibrio desulfuricans to recover the precious metal palladium from industrial waste sources.

Right: Bacterial cells that can accumulate high quantities of precious metals are an efficient and green alternative to traditional recycling methods. Here E. coli cells are surrounded by nanoparticles of palladium and gold (black deposits) Credit: Kevin Deplanche

Writing in Microbiology, researchers point out that palladium is one of the platinum group metals (PGMs) which are among the most precious resources on earth, possessing a wide variety of applications, due to their exceptional chemical properties.

PGMs are routinely used in many catalytic systems and are the active elements of autocatalytic converters that reduce greenhouse gas emissions.

Dr Kevin Deplanche who led the study explains. “These metals are a finite resource and this is reflected in their high market value,” he said. “Over the last 10 years, demand has consistently outstripped supply and so research into alternative ways of recovering palladium from secondary sources is paramount to ensuring future availability of this resource.”

Previous work in the team’s lab showed that Desulfovibrio desulfuricans was able to reduce palladium in industrial wastes into metallic nanoparticles with biocatalytic activity. Now, the precise molecules involved in the reduction process have been identified. Hydrogenase enzymes located on the surface membrane of the bacterium carry out the reduction of palladium, which results in the accumulation of catalytic nanoparticles.

The bacterial cells coated with palladium nanoparticles are known as ‘BioPd'.  The group believes BioPd has great potential to be used for generating future clean energy.

“Research in our group has shown that BioPd is an excellent catalyst for the treatment of persistent pollutants, such as chromium, that is used in the paint industry. BioPd could even be used in a proton exchange fuel cell to make clean electricity from hydrogen,” says Dr Deplanche.

“Our ultimate aim is to develop a one-step technology that allows for the conversion of metallic wastes into high value catalysts for green chemistry and clean energy generation,” he said. 

Food safety becoming 'old hat'
At  EBI Food Safety in the Netherlands Wageningen, the first commercial bacteriophage product, Listex, which targets Listeria monocytogenes-pathogenics with a 30% mortality rate. Listex was granted the US FDA-GRAS (generally regarded as safe) approval in October 2006; organic EU approval in June 2007, and an extension of GRAS approval from the FDA and USDA for use with all food products susceptible to Listeria.

“This opened the door for meat and fish processing companies to also use Listex,” sais Mark Offerhaus, EBI’s CEO. “The reason for using natural phages for nano bio-control is that these are extremely host-specific,” he says. “Phages do not affect desirable flora or starter cultures; are completely biological; do not change the taste, smell, or food color; are easy to apply, etc.”

Electronic and power work for the bio-phages
Phages are very useful nano-structure tools. For instance, peptides with binding specificity use the phage display (a test to screen for protein interactions) to indicate silicon dislocations and defects in semiconductor processing, as well as in the assembly of alloys for thin-film battery anodes and nanowire creation.

Professor Angela Belcher (right) has worked for years with the bacteriophage M13, genetically engineering the virus to coat itself in a compound semiconductor sheath, then locate and bridge two electrodes, to form the critical part of a field-effect transistor (FET).

M13 is now being bio-templated for developing hi-tech batteries that could be woven into clothing for powering portable devices such as GPS units, smart phones and radio's. Such batteries would generate less heat than conventional lithium-ion batteries, and allow soldiers to shed weight. 

Medical zip code identifiers
In August Mercator Therapeutics Inc raised $2m seed financing and licensed technology from the University of Texas M.D. Anderson Cancer Center to develop cancer drugs using a first-of-its-kind technology.

The Wellesley, Mass-based biotech claims to be first to use in vivo phage display technology systematically to develop cancer therapies. 

Mercator's technology was discovered and developed by Wadih Arap (right)  and Renata Pasqualini (left), Mercator co-founders, and others at M.D. Anderson.

The two pioneered the use of in vivo phage display to identify targeting peptides that are believed to selectively deliver tumor-killing payloads without damaging surrounding tissue.

The technology centers on an a phage that can express all possible permutations of a peptide. Using just a few microliters, an entire universe of protein interacting sites can be displayed on the capsid of the virus. Exposed to a cell or injected in a subject, probes can be recovered that systematically find their way to target organs, fishing out the desired receptor, or 'Zip Codes' as Pasqualini, describes it.

The technology was based on the theory that a specific address code existed in blood vessels so that proteins and cells would know where to find them, she explained. But the code can't be seen once a tissue biopsy is ground up in a petri dish.

"To discover the Zip codes, you need to do it in live subjects," Pasqualini said.  Focus of the research in the Arap-Pasqualini lab has been to deliver an agent that induces cell death in the tumor and not in healthy tissue. 

The designer approach
In spring this year, the J Craig Venter Institute made global headlines with its synthentic self replicating cells and the microbiome. Two months later Exxon Mobile put $600m into Dr Venter's commercial company Synthetic Genomics Inc, with a new facility opened in San Diego to study algae-growing methods and oil extraction techniques. 

Dr Venter is reported  as wanting to create — bacteria, algae or even plants — that are designed from the DNA up to carry out industrial tasks displacing the fuels and chemicals currently now made from fossil fuels.

“Designing and building synthetic cells will be the basis of a new industrial revolution,” he says (right). “The goal is to replace the entire petrochemical industry.”

BP has also invested with Synthetic Genomics to study microbes that might help turn coal deposits into cleaner-burning natural gas. Malaysian conglomerate Genting, wants to improve oil output from its palm tree plantations.

The next move is out of petrochemicals and into pharmaceuticals with giant Novartis reported as likely to work with SGI to synthesize influenza virus strains as a potentially faster way to make flu vaccines.

Interesting to see if modification or original design will makes the most headway with the bio tool revolution.