ESA EuTEF Module takes up its position on the Space Station

The European Technology Exposure Facility (EuTEF) attached to the ESA Columbus module of the International Space Station during orbital flight. 

Credit: DLR, Institute of Aerospace Medicine /Dr. Gerda Horneck

In the movies, humans often fear invaders from Mars.

These days, scientists are more concerned about invaders to Mars, in the form of micro-organisms from Earth.

Three recent scientific papers examined the risks of interplanetary exchange of organisms using research from the International Space Station.

All three, Survival of Rock-Colonizing Organisms After 1.5 Years in Outer Space, Resistance of Bacterial Endospores to Outer Space for Planetary Protection Purposes and Survival of Bacillus pumilus Spores for a Prolonged Period of Time in Real Space Conditions, have appeared in Astrobiology Journal.

Organisms hitching a ride on a spacecraft have the potential to contaminate other celestial bodies, making it difficult for scientists to determine whether a life form existed on another planet or was introduced there by explorers.

So it's important to know what types of micro-organisms from Earth can survive on a spacecraft or landing vehicle.

Currently, spacecraft landing on Mars or other planets where life might exist must meet requirements for a maximum allowable level of microbial life, or bioburden.

These acceptable levels were based on studies of how various life forms survive exposure to the rigors associated with space travel.

Kasthuri J. Venkateswaran

"If you are able to reduce the numbers to acceptable levels, a proxy for cleanliness, the assumption is that the life forms will not survive under harsh space conditions," explains Kasthuri J. Venkateswaran, a researcher with the Biotechnology and Planetary Protection Group at NASA's Jet Propulsion Laboratory and a co-author on all three papers.

That assumption may not hold up, though, as recent research has shown that some microbes are hardier than expected, and others may use various protective mechanisms to survive interplanetary flights.

These are electron micrographs of Bacillus pumilus SAFR-032 spores on aluminum before and after exposure to space conditions. 

Credit: P. Vaishampayan et al., Survival of Bacillus pumilus Spores for a Prolonged Period of Time in Real Space Conditions. Astrobiology Vol 12, No 5, 2012.

Spore-forming bacteria are of particular concern because spores can withstand certain sterilisation procedures and may best be able to survive the harsh environments of outer space or planetary surfaces.

Spores of Bacillus pumilus SAFR-032 have shown especially high resistance to techniques used to clean spacecraft, such as ultraviolet (UV) radiation and peroxide treatment.

When researchers exposed this hardy organism to a simulated Mars environment that kills standard spores in 30 seconds, it survived 30 minutes.

For one of the recent experiments, Bacillus pumilus SAFR-032 spores were exposed for 18 months on the European Technology Exposure Facility (EuTEF), a test facility mounted outside the space station.

"After testing exposure to the simulated Mars environment, we wanted to see what would happen in real space, and EuTEF gave us the chance," says Venkateswaran.

"To our surprise, some of the spores survived for 18 months." These surviving spores had higher concentrations of proteins associated with UV radiation resistance and, in fact, showed elevated UV resistance when revived and re-exposed on Earth.

The findings also provide insight into how robust microbial communities are able to survive in extremely hostile regions on Earth and how these microbes are affected by radiation.

Russian Cosmonauts EVA search for bacterium corroding ISS

The Russian cosmonauts, Alexander Misurkin and Fyodor Yurchikhin, staying aboard the International Space Station (ISS), recently conducted at EVA from the Space Station with the aim of examining the ISS body to find out whether there is a bacterium there that can destroy its surface.

The bacteria research, done by scientists, has been going on for more than 20 years now.

Over the past period the Russian Space Agency has given Russian and foreign biologists more than 1 million pestiferous microbes that can destroy metals and polymers.

According to information obtained by experts during the past decades, we know that the life cycle of such microorganisms can last from 20 to 30 minutes.

Bacteria have enough time to grow, multiply, to destroy several molecules of the material they choose, and die.

In a 10-year period nearly 200,000 generations of microbes undergo changes, scientists say.

As a rule, there are many microbes in pipelines, air conditioners, cooler-dehumidifier units, oxygen electrolysis units, electric and hydraulic lines, helmets, and on skin-plating.

OxFord University: Flesh-eating bacteria inspire superglue

A bio-inspired superglue has been developed by Oxford University researchers that can’t be matched for sticking molecules together and not letting go.

It could prove to be a very useful addition to any toolbox for biotechnology or nanotechnology. You could use the glue to grab hold of proteins or stick them immovably to surfaces. You could even use it to assemble proteins and enzymes to build new structures on the nanometre scale.

‘We’re very interested in creating protein assemblies. We want to be able to treat proteins like Lego,’ explains Dr Mark Howarth, who with his graduate student Bijan Zakeri at the Department of Biochemistry developed the superglue. ‘But previously we’ve been limited to ill-controlled processes or have had to build using weak biological interactions.’

The Oxford biochemists came up with their new super-strength molecular glue by engineering an unusual protein from a type of bacteria that can cause life-threatening disease.

While many people carry Streptococcus pyogenes in their throat without any problems, the bacteria can cause infections. Some are mild, like impetigo in infants or a sore throat, but some can kill, like toxic shock syndrome or flesh-eating disease.

What attracted the biochemists’ interest was a specific protein which the bacteria use to bind and invade human cells.

‘The protein is special because it naturally reacts with itself and forms a lock,’ says Mark.

All proteins consist of amino acids linked together into long chains by strong covalent bonds. The long chains are folded and looped up into three-dimensional structures held together by weaker links and associations.

The protein FbaB from S. pyogenes has a 3D structure that is stabilised by another covalent bond. This strong chemical bond forms in an instant and binds the loops of the amino acid chain together with exceptional strength.

Mark and his colleagues reckoned with a bit of engineering they could split the protein around this extra covalent bond. Then, when the two parts were brought together again, they might dock and form this strong bond once more.

The two parts would be locked together immovably – stapling together anything else attached to their tails.That is what the researchers have now demonstrated in this week’s PNAS.

They’ve nicknamed the larger fragment which formed the bulk of the original protein ‘SpyCatcher’. Once SpyCatcher gets hold of the shorter protein segment, ‘SpyTag’, it never lets go.

At least, the researchers with their collaborators at the University of Miami tried to measure the force needed to pull apart SpyTag from SpyCatcher using an atomic force microscope.

But when they pulled on each end, the chemical links holding the proteins to the apparatus broke first. Boiling in detergent won’t separate the protein fragments either.

‘Our system forms rapid covalent bonds with high efficiency and high stability,’ says Mark.

When SpyCatcher and SpyTag are brought together, they bond in minutes with high yield. It doesn’t matter whether it is in acidic or neutral conditions, or whether it is 4°C or 37°C.

They will stick together in test tube reactions or inside cells. And importantly, they don’t stick to other things – there’s no equivalent of getting your fingers stuck to the Airfix model you’re building.

Mark explains that there isn’t really any equivalent way to bind biomolecules together. There are chemical reactions that can join two proteins together covalently but often only small proportions react, they take a long time, or they require UV light, toxic catalysts or reaction conditions that could damage living cells.

The ability to attach SpyCatcher and SpyTag onto other molecules you want to glue together could have many applications. For example, sticking all the enzymes involved in a chemical process into a small factory could speed reactions and increase yields.

Or you might want to bring all the elements together that plants use to turn sunlight into energy with only water as a waste product. Scientists have long wanted to come up with ways of achieving photosynthesis artificially for useable green energy.

But the first uses of the molecular superglue may well be in the research lab, grabbing hold of structures within biological cells. That way you could resist the forces generated by important motors, machines and transporters inside the cell.

Mark and his team are now working on developing the molecular superglue technology through Isis Innovation, the University of Oxford’s technology transfer company.

Chemists discover most naturally variable protein in dental plaque bacterium

The chemists, who announced their discovery in this week's early online edition of the journal Proceedings of the National Academy of Sciences, say they believe the extreme variability of the protein they discovered in the bacterium Treponema denticola evolved to adhere to the hundreds of different kinds of other bacteria that inhabit people's mouths.

They call the protein they discovered "Treponema variable protein," or TvpA for short, and estimate that it is a million to a billion times more variable than the proteins that play a primary role in vertebrate immune systems -- the only other known natural system for massive protein variation.

"In Treponema denticola, we found a protein we call TvpA, that varies considerably more than proteins of the immune system and, to our knowledge, this protein is the most variable natural protein described to date," said Partho Ghosh, a professor of chemistry and biochemistry at UC San Diego who headed the research effort.

"We don't know what it does in this bacterium, but our hypothesis is that it enables it to adhere to the biofilm, commonly known as dental plaque, that exists in people's mouths."

Ghosh explained that dental plaque varies from person-to-person in the kinds of bacteria that adhere to the teeth to form this biofilm. Because plaque grows in a sequential way and because T. denticola is one of the last key players in the formation of plaque, Ghosh said the bacterium has no idea what kinds of other bacteria will be present to adhere to.

"We suspect that by varying TvpA, T. denticola is able to find a TvpA variant that is able to adhere to whichever bacterium is already present in the biofilm," Ghosh said.

Paper Money is poison: Worldwide it Contains Bisphenol A

The cash register receipts that people place near paper money in billfolds, purses, and pockets has led to a worldwide contamination of paper money with bisphenol A (BPA),a potentially toxic substance found in some plastics, thermal paper and other products.

The amounts of BPA on dollars, Euros, rubles, yuans, and other currencies, are higher than in house dust, but human intake from currency is at least 10 times less than those from house dust.

That's the conclusion of a new study in the ACS' journal Environmental Science & Technology.

Kurunthachalam Kannan and Chunyang Liao point out that manufacturers use BPA to make polycarbonate plastics used in some consumer products, including water bottles, sports equipment, and household electronics.

Studies indicate that BPA acts as an endocrine disruptor -- meaning it mimics the action of the sex hormone estrogen. Exposure to BPA has been linked to a variety of health problems. Although a recent study found traces of BPA in U.S. currency, nobody knew until now about BPA in paper money worldwide.

The scientists' analysis of 156 pieces of paper money from 21 countries found that all contained traces of BPA. The report notes, however, that "estimated daily intake from paper currencies were 10-fold lower than those reported from exposures due to [indoor] dust ingestion in the United States."

The highest BPA levels were in paper money from Brazil, the Czech Republic and Australia, while the lowest occurred in paper money from the Philippines, Thailand, and Vietnam. Levels in U.S. notes were about average.

Kannan and Liao also found that the most likely source of the BPA in the currency is the thermal paper used in cash register receipts. They showed that receipts can transfer BPA onto cash when placed next to it or when a receipt is touched before handling currency.

"Although high levels of BPA were measured in paper currencies, human exposure through dermal [skin] absorption appears to be minor," the article notes.

New bacteria found living on Titanic wreck

A new bacteria has been found in the wreck of the Titanic, growing in "rusticles," icicle-like structures on the ship's rusting iron, Canadian researchers say.

The previously unknown bacteria, Halomonas titanicae, was found in samples of rusticles taken from the Titanic by the Mir 2 robotic submersible in 1991, the BBC reported Monday.

Researchers from Dalhousie University and the Ontario Science Center in Canada and the University of Seville in Spain isolated the bacteria from those samples.

DNA sequencing showed them to be a new species of the Halomonas genus found in salt water environments.

The bacteria may shed light on the mechanism by which rusticles form and the "recycling" that such microbes carry out on submerged metal structures, the researchers said.

Such findings could have relevance to the protection of offshore oil and gas pipelines and the safe disposal at sea of ships and oil rigs, they said.

The find has been published in the journal International Journal of Systematic and Evolutionary Microbiology.

Alchemy is back - Gold found in Bacterium

Move over, Midas. A genetically modified version of a bacterium that extracts gold from its environment can signal the presence of the precious metal. The result could be a boon for prospectors.

Some bacteria are known to be associated with gold deposits, but it has been unclear whether they play a role in its production – and if so, what that is.

Now Frank Reith of the University of Adelaide, South Australia, has found that dissolved gold is harmful to the bacterium Cupriavidus metallidurans, as it forms a toxic sulphur-containing compound when it is absorbed from the environment. This compound inhibits the bacterium's enzyme function, prompting the distressed microbe to activate a cluster of "gold detox" genes that produce enzymes able to convert the soluble gold compounds into harmless particles of metallic gold.

Hand-held prospector
Knowing how microbes do this will open up a whole new way of prospecting, says co-author Gregor Grass of the University of Nebraska. Reith and Grass have developed a genetically modified version of C. metallidurans that produces a visible response when the detox genes are switched on.

"When the microbes come into contact with gold, they flash a light that can be detected using a hand-held photometer," says Grass. He envisages that prospectors will be able to detect whether gold is present simply by taking a sample of soil and adding modified bacteria to it.

"There have been reports that bacteria can enhance the production of gold for some time," says John Stolz, an environmental microbiologist at the Bayer School of Natural and Environmental Sciences at Duquesne University in Pittsburgh, Pennsylvania. "But this is the first time scientists have actually identified how they do it."

Journal reference: Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0904583106.