Hold tight: A mussel-inspired ‘living glue’

ResearchBlogging.orgMussel (Mytilus galloprovincialis) Adhesive Glue Many aquatic animals spend much of their lives stuck to surfaces that can include rocks, ships or even whales. Limpets and sea stars, for example, use a form of adhesion that allows them to move on the surface they have colonised, but which makes them very hard to remove from that surface. Barnacles and mussels, meanwhile, produce fully-fledged underwater glues, known as bioadhesives; once they attach to a surface, these animals spend the rest of their lives stationary. Researchers have been aware of the strength of these glues for some time, but attempts to create artificial substances that rival their underwater adhesive power have been largely unsuccessful – until now.

Dr Timothy Lu and his colleagues at the Massachusetts Institute of Technology have created a novel glue based on byssus, the bioadhesive produced by the Mediterranean mussel (Mytilus galloprovincialis). Their results, recently published in the journal Nature Nanotechnology, show that the substance is 50% stronger than any bio-inspired, protein-based underwater glue produced so far.

To achieve such strong adhesion, Dr Lu and his team used two proteins from the mussel’s foot, which the animal uses to shoot byssus into any crevice it wants to attach to. The researchers inserted the genes that encode the production of these proteins into Escherichia coli bacteria, which are themselves known for the sticky fibres they produce to adhere to our intestines. As a result, the bacteria produced a ‘hybrid’ glue, although they did not survive the process.

Mussel adhesives and E. coli adhesives use different types of chemicals. Byssus is based on a material called L-3,4-dihydroxyphenylalanine, or DOPA, which is thought to be responsible for the water resistance and fast-acting nature of this glue. E. coli, on the other hand, produce amyloids, fibre-like structures that are notable for their self-assembly: no external guidance is needed for the molecules to arrange themselves into networks that grow denser and larger as long as more raw material is supplied. A combination of these two types of adhesives, the researchers reasoned, would be particularly potent.

Despite using mussel proteins, there were no aquatic creatures in the lab at any point. The scientists simply ordered the DNA sequences responsible for producing the proteins from an online database. This allowed them to experiment with many different proteins, mixing and matching them to find out what they do – and to identify the ones that produced the best adhesives when inserted into E. coli.

The two proteins Dr Lu and his colleagues used are just a few of the many that play a role in producing byssus. We do not yet know what each mussel protein does, and using just two of them yielded an imperfect adhesive. For example, while the glue worked well underwater, it was much less effective when in direct contact with air. We know that some barnacles and mussels live in intertidal areas that are only submerged part of the time, so it must be possible to produce adhesives that work on land using mussel proteins – we just haven’t found the right ones yet.

Dr Lu notes that it is possible to extract the adhesive substance from the E. coli without killing them. He is currently working to introduce this feature, which would result in a ‘living’ glue with self-repairing properties: the bacteria could continuously produce more molecules to add to the framework. Repairing damage in ships’ hulls is just one example of the possibilities of such an adhesive.

Despite its imperfections, Dr Lu believes that there will be plenty of interest in the new adhesive if he and his team manage to produce it in larger quantities. While it would not replace cheap, generic superglue, a bioadhesive that works well in wet conditions could become an invaluable tool for surgeons, allowing them to seal wounds more easily and less intrusively than with stitches.

Much research remains to be done to unlock the secrets of mussel glue and how best to combine the proteins involved in producing it. E. coli have proven a useful basis for producing the substance – in fact, Dr Lu and his colleagues have used them to produce a range of substances in previous research. They have taken an important step towards making a strong, commercially viable underwater glue – and it may only be a matter of time until scientists discover an adhesive that can out-stick mussels themselves…

Jon Fuhrmann

Zhong, C., Gurry, T., Cheng, A., Downey, J., Deng, Z., Stultz, C., & Lu, T. (2014). Strong underwater adhesives made by self-assembling multi-protein nanofibres Nature Nanotechnology, 9 (10), 858-866 DOI: 10.1038/nnano.2014.199

Image Credit: Ian Sutton on Flickr under CC BY 2.0.
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Microbe Talk: October 2014

Rasacee_couperose_zones.svgYou might not know it, but right now there are very likely to be microscopic mites living on your face. These mites are microscopic, so you won’t see them if you look in the mirror. For most of us, these mites are totally harmless and just live off the natural oils produced by our skin. However, they have also been implicated in the skin condition rosacea, which potentially affects as many as 1 in 10 people. We spoke to Fred McMahon, a PhD student at Maynooth University, about the mites and how the bacteria within them may be at the root of rosacea.

Show notes:

Don’t forget, you can subscribe to Microbe Talk on iTunes. You can also find us on Stitcher.

Benjamin Thompson

Image credit: Karl Udo on Wikimedia Commons, via Free Art License 1.3
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World Polio Day 2014

Polio Vaccination - World Polio Day 2014. Credit: UNICEF Ethiopia24 October is World Polio Day, an event that aims to raise awareness of the continuing threat of polio to children in some parts of the world. A global effort to eradicate the disease has been ongoing for 26 years, reducing the number of cases from over 350,000 in 1988 to 406 in 2013. Today, only three countries – Afghanistan, Pakistan and Nigeria – have yet to eradicate the virus. However, in 2014, new cases of polio have also been documented in Iraq, Syria, Cameroon, Equatorial Guinea, Somalia and Ethiopia – all countries that were previously polio-free. This reintroduction of the disease highlights that as long as a single person remains infected, polio can return. According to the World Health Organization, a renewed spread of polio could cause up to 200,000 new cases over the course of a decade and cost the global economy billions of dollars.

What is polio?
Polio is short for Poliomyelitis and is also known as infantile paralysis. It is an infectious disease caused by the three different types of poliovirus, which mainly infect children under 5 years of age. Polioviruses can live in an infected person’s faeces for several weeks and are transmitted mainly via the faecal-oral route, meaning that they can spread through water supplies and food in unsanitary conditions. Polio can also be spread through droplets from the sneezes and coughs of infected people. Continue reading

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Research Councils UK highlights initiatives to tackle antimicrobial resistance

Big BenYesterday, Research Councils UK (RCUK) – the partnership of the UK’s seven research councils – set out the initiatives they are taking to tackle the serious issue of antimicrobial resistance (AMR). RCUK was responding to the House of Commons Science and Technology Committee’s recent report Ensuring access to working antimicrobials, which highlighted the need for ‘improved stewardship to extend the effective life of existing antimicrobials and increased innovation to develop new treatments.’

Responding to the Science and Technology Committee’s call for strategic coordinated action, RCUK highlighted that under the umbrella of the Antimicrobial Resistance Funder’s Forum (AMRFF), the research councils, along with other governmental bodies and charities, are now collaborating together to better support, coordinate and raise the profile of AMR research, both in the UK and internationally. Continue reading

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The right place at the right time: new bacterium navigates using Earth’s magnetic field

ResearchBlogging.orgMTB Title ImageMany migratory birds have a mysterious ability to return home with remarkable accuracy, even from halfway around the world. Since the invention of the compass some 2,000 years ago, humans have been able to emulate this, albeit on a limited scale. But the discovery that even microbes can navigate in a similar manner is relatively recent. It was only in 1975 that Richard Blakemore, of the Woods Hole Oceanographic Institute in Massachusetts, described the first members of a small group of microbes we now know as magnetotactic bacteria (MTB). Their ability to sense the geomagnetic field and move accordingly is known as magnetotaxis.

Since 1975, a range of MTB have been discovered in several different branches of the tree of life. Besides magnetotaxis, the main thing they have in common is that they live in water and have flagella – whip-like appendages that they use to swim. Unlike birds and people, however, MTB do not use their inbuilt compass to move in a specific direction. In fact, they use magnetotaxis to avoid any north-south or east-west movement: MTB only move up or down within the body of water they live in. This is because they require very specific levels of oxygen concentration, which generally varies with water depth. Moving horizontally would quite simply be a waste of energy for these bacteria. Continue reading

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UK Fungus Day 2014

Fungus Day12 October 2014 is UK Fungus Day, held by the British Mycological Society to showcase the diversity and usefulness of fungi, and the benefits of mycology (the study of fungi). Many people equate fungi with mushrooms, but mushrooms are only the visible, above-ground part of certain types of fungi. The bulk of such a fungus’s volume is underground and consists of microscopic threads called hyphae, which can form huge, interconnected networks. This means that mushrooms some distance apart may well belong to the same fungal organism.

Like plants and animals, fungi belong to the domain Eukaryota, which contains all organisms whose cells contain a nucleus. Unlike other eukaryotes, however, the cell walls of fungi contain chitin, a chemical structure also found in the hard shells of many insects and crustaceans.

Fungi are found around the world, with some 100,000 species currently known to mycologists. However, it is estimated that several million different species exist worldwide, so there is plenty of scope for discovery. Fungal species can grow in the most inhospitable regions, including deserts, deep ocean seafloors, and severely irradiated ground; some can even survive the intense ultraviolet and cosmic radiation in outer space, as findings aboard the International Space Station have shown.

Until just a few decades ago, fungi were thought to be closely related to plants: they both grow in similar habitats and do not move, and many fungi have similar above-ground shapes as flowering plants. Since the advent of molecular methods, however, we know that plants and fungi became genetically separate about a billion years ago. In fact, fungi are more closely related to animals than to plants! Continue reading

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New to Science – October Edition

ECleanroom at the Goddard Space Flight Center, Greenbelt, MD, USAach month, the Society for General Microbiology publishes the International Journal of Systematic and Evolutionary Microbiology, which details newly discovered species of bacteria, fungi and protists. Here are a few of the new species that have been discovered, and the places they’ve been found. The full papers are available to journal subscribers, but the abstracts are free to read.

The harvesting season is slowly coming to a close in large parts of the northern hemisphere – incidentally, the word ‘harvest’ itself originates in the Old English hærfest, meaning ‘autumn’. Microbiologists, too, have been busy in recent weeks, and as preparations begin for various harvest and thanksgiving celebrations around the world, we are introduced to some intriguing new agriculturally themed species in the latest edition of IJSEM.

Any idyllic notions you may hold about farm work are quickly dispelled when it comes to microbiology. An American team, for example, identified Peptoniphilus stercorisuis in a sample from a storage tank containing swine manure. The bacterium is the first known member of a new taxonomic family, the Peptoniphilaceae. Continue reading

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