This week on the Naked Scientists we have a whole host of experts in bacteria, fungi and viruses. We'll have Dr Tim Wreghitt (Addenbrooke's Hospital) discussing noroviruses, Dr Ali Ashby discussing her fun work with fungi and in kitchen science with the help of Dr Gillian Fraser we'll be discovering where there are more bacteria: on a toilet seat or a kitchen worktop?

Mushrooms – many more uses than just housing for smurfs

Think all things are divided in to two Kingdoms? Think again ... enter the Fungi. Fungi were originally classed as plants, but are now classed separately due to their heterotrophic properties (they don't fix their own carbon through photosynthesis but use carbon fixed by other organisms for metabolism). Fungi occur in every environment and play a considerable role in most ecosystems. In addition to bacteria, fungi are the main decomposers in the majority of terrestrial environments giving them a critical role in biogeochemical cycles and many food-webs. Fungi also play a role in many symbiotic relationships; one of their most significant ones involves plants. The fungus lives on the plant's roots, the plant donates sugars and other carbohydrates to the fungus which result from photosynthesis, while the fungus donates water and mineral nutrients in a more efficient way than the plant roots alone could obtain. The fungi also protect against diseases and pathogens and provide other benefits to the plant. Fungi have been used by people in a vast number of ways for a very long time. Many types of mushrooms and other fungi are cultivated or picked from the wild and can be eaten directly, while yeast cultures are used in many foodstuffs. Fungal growth also occurs in certain types of cheeses that gives them their flavour. Another human application of fungi utilizes the fact that many fungi compete with other organisms, or directly infect them, lending them to be used in biological pest control.

There are several other fungal and plant interactions and this area is the specialization of Ali Ashby (University of Cambridge); who looks at how such interactions evolve, particularly with regard to light leaf spot on rapeseed – a fungal disease which attacks leaves. Ali is committed to raising awareness of fungi and has exhibited with the British Mycological Society at the Malvern plant show, where their stand won a gold medal - see figure 1.

Where is there more bacteria – on the toilet seat or kitchen worktop?

In Kitchen Science this week we'll be analysing the bacteria content on a toilet seat and also on a kitchen worktop. Then we'll find out which one was more contaminated, think you can predict the result? Then vote on our forum where we have photographs of the two plates taken following the swabbing.

Noroviruses...the Naked facts

Also this week we'll be talking to Consultant Virologist Dr Tim Wreghitt about his work with Noroviruses. Noroviruses are viruses which cause large outbreaks of diarrhoea and vomiting with a history of occurring in family homes, hospitals, schools and on cruise ships. Noroviruses change the makeup of their RNA every few years, leading to new outbreaks in the community. As humans are only immune to reinfection for a few months after infection, we are all likely to have several episodes of norovirus diarrhoea and vomiting during our lives.

So why does the virus cause such large outbreaks and occur in communal areas? The answer lies in how it spreads. Noroviruses cause projectile vomiting with no warning, so infected people are occasionally sick in communal areas, such as hospitals. Once this has happened, the area around the incident is infectious and people in the vicinity are at high risk of developing the illness. The only way to prevent further spread is to promptly clean the area with chlorine-based disinfectant or hot soapy water and to restrict human access.

Large outbreaks also occur on cruise ships and in hospitals. Prompt decontamination of areas where people have vomited and removal of symptomatic staff from public contact are the only effective means of control. There is no vaccine or anti-viral treatment. Symptoms take about 2-4 days to resolve and the incubation period is 24-48 hours.

It is also possible to catch the virus from eating contaminated seafood, particularly bivalve molluscs (eg cockles and oysters). This occurs through sewage contamination of shellfish beds, which can then cause human disease unless those foods are cooked thoroughly before being eaten. Occasionally, food preparers can contaminate food by not washing their hands thoroughly after going to the toilet – causing large outbreaks of diarrhoea and vomiting.

To hear more about bacteria, fungi and viruses, tune in to the Naked Scientist's Radio show and Podcast.