Issues Magazine


By By Sally Woollett

Editor, Issues

An overview of what's in this edition of Issues.

There are more of their cells in a teaspoon of intestinal contents than people who have ever lived, and we carry them around without even thinking about it – unless they make us sick. This is why bacteria have such a bad reputation. We only tend to notice them when they cause illness. We forget (or don’t know) about the many essential jobs they do.

Bacteria are just one of several types of (for the most part) living things that have been called microbes (microorganisms). Others that go by this name include Archaea, protozoa, algae and fungi. Some are single-celled and some multicellular; others (viruses) are not even considered to be alive.

“An alien observer with very powerful vision might classify a person not as a single organism, but as an entire ecosystem capable of movement,” says Bonnie Laverock, a marine microbial ecologist at the University of Western Australia’s Oceans Institute (p.6). This is Laverock’s introduction to the work of the Human Microbiome Project, which is making some incredible findings about the microbes that call the human body home. “The most important thing to realise about these microbes is that they are part of a normal, healthy body. It is only the explosion in their abundance in relation to other, competing microbes that causes harm to humans,” Laverock continues. The same idea applies to aquatic environments – think of the algal blooms that result from an abundance of phytoplankton.

Steven Semiatin discusses a domain of life with which we are less familiar and has only recently been classified separately from bacteria: Archaea (p.11). They don’t have any pathogens that we know of, and aren’t part of any food cycles. “Some scientists think these microbes are similar to the original ancestors of all modern life,” Semiatin says. Some Archaea can survive in such incredibly inhospitable environments that they’ve earned the title “extremophile”.

While extremophiles are getting all the attention, sexually transmitted infections (STIs) never seem to come out of the closet. “The fervent hope of many sexual heath professionals is that both the prevention and management of STIs will eventually be seen in the same way as regular exercise and a balanced diet – as strategies that promote and support a healthy lifestyle,” says Cheryl Power of the University of Melbourne (p.14). A reluctance to talk about STIs has an impact on management strategies, and thus their incidence continues to grow.

Measles, mumps and whooping cough are making a comeback, says Loretta Marron of Friends of Science in Medicine (p.17), and today’s parents were not around to see the disastrous consequences of these viral and bacterial diseases before vaccinations were available. “The message is straightforward: immunisation prevents outbreaks of disease and saves many lives,” Marron says, and parents concerned about the effects of vaccination should discuss them with a GP, paediatrician or pharmacist.

We have a lot to learn from forgotten epidemics, says Ian Townsend (p.19), but often we choose not to remember: “In Australia, when it comes to epidemic disease we have a collective amnesia. The terrifying epidemics that have swept through Australia in the past – diseases such as smallpox and plague, tuberculosis and polio, childhood killers such as whooping cough and diphtheria – are not only outside the experience of most people, but the events themselves appear to have been erased from our cultural memory.”

Siouxsie Wiles of the Bioluminescent Superbugs Laboratory at the University of Auckland has had a lifelong fascination with bacteria and how they cause disease. One of the things she does is use light as a way to determine numbers of bacteria. “Because only living bacteria glow, bioluminescence can also serve as an excellent marker for whether a particular treatment is working or not – if it is effective, the amount of light will decrease as bacteria are killed,” Wiles says (p.23). Her current research relates to drugs for tuberculosis. Wiles tells us that one in every 15 newly diagnosed cases of tuberculosis is of a drug-resistant type. In these cases, treatment is a very difficult, time-consuming and expensive process. So how does this drug resistance occur?

There are several reasons, says Roy Robins Browne of The University of Melbourne and the Murdoch Children’s Research Institute (p.26). One of these is that “a generation for an average bacterium is around 20–30 minutes, while for humans it is more like 20–30 years. In other words, bacteria replicate more than 500,000 times faster than ourselves. This means they can adapt and respond to or recover from a threat to their survival far more rapidly than we can.” Research is underway to target the ability of bacteria to cause disease rather than their growth.

A prime example is methicillin-resistant Staphylococcus aureus (MRSA), which “has emerged as a significant and growing problem in small animal and equine hospitals and intensive livestock facilities,” according to Darren Trott, David Jordan, Mary Barton, Sam Abraham and Mitchell Groves at the School of Animal and Veterinary Sciences, University of Adelaide (p.31). Usually acquired in hospital and from another person, MRSA, which causes serious and sometimes fatal disease, has now been identified in other animals – a finding of concern to veterinarians.

Bacteria have unique relationships with plants as well as with people. “When plants were domesticated for agricultural purposes… the critical role of their microbial partners was not yet recognised, so plants have been bred, adapted and grown around the world without attention to the microbial milieu in which they evolved,” say Ann Reid and Shannon Greene of the American Society for Microbiology (p.33). Determining the best microbial environments for plants could reduce their need for fertilisers, make them more resistant to environmental stressors and thus contribute to the pressing global problem of food security.

“Not often does a significant breakthrough occur in the management of an introduced perennial grass weed that does not include a new or improved chemical herbicide,” says David Officer (p.38). The “good guys” in this case have turned out to be from a natural source in the form of the fungus Nigrospora oryzae, which is acting as a biological control agent on an introduced species, giant Parramatta grass, affecting productive land in NSW.

“We have the technology to upscale what microorganisms in the environment do and to apply it to our industrial processes,” says Carla Zammit at the University of Adelaide (p.41). Some microbes, such as the bacterium Cupriavidus metallidurans, can extract certain metals from their ores. This can be done via bioleaching, in which the minerals become soluble during oxidation in acidic conditions, or through bio-oxidation, where the microbes break down the sulfides of an ore.

If you think the Aussie mosquito is just a night-time nuisance, then think again. “The reality is that Ross River and Barmah Forest (viruses) are now commonly reported from southern states. In fact, outbreaks are increasingly occurring on the fringes of cities such as Sydney, Melbourne and Perth,” says University of Sydney entomologist Cameron Webb (p.44). Mosquito-borne viruses can have nasty and long-lasting effects, so it’s important to take preventative measures around the home and in the great outdoors.

Viral infections, animal dander and other allergens such as house dust mites and mould spores are some of the triggers of a condition endured by one in ten Australians: asthma. “Respiratory viruses are important in children with asthma, but bacteria and fungi can also cause exacerbations of asthma, and are more important in older children and adults,” explain Christiana Willenborg and Sacha Stelzer-Braid of the Virology Research Laboratory, Prince of Wales Hospital. “Whether it is causal or genetic factors linking HRV [human rhinovirus] and RSV [respiratory syncytial virus] to asthma later in life is still not known and much debated.”