The stories appear all too often. E. coli-contaminated beef causes sickness across a multistate region. Cryptosporidium in water sickens thousands in Milwaukee.

The stories underscore a very tough problem: As food and drink travels from source to processor to grocer and finally to you, it’s constantly vulnerable to contamination by disease-causing organisms.

To strengthen efforts to keep food safe, the UW-Madison has hired four new researchers through its cluster hiring initiative – a program designed to build multidisciplinary teams in critical subject areas.

“There was a serious deficiency – a low critical mass” in the food safety area, says Michael Pariza, who led the team that proposed the food safety hirings.

Though the newcomers have appointments in several UW-Madison departments and colleges, all are affiliated with the Food Research Institute.

The four new hires are:

* Jaehyuk Yu, a fungal molecular geneticist with the Department of Food Microbiology and Toxicology
* Nancy Keller, a molecular biologist with the Department of Plant Pathology and Department of Food Microbiology and Toxicology
* Ferencz Denes, a plasma engineer with the Department of Biological Systems Engineering and the College of Engineering”s Center for Plasma-Aided Manufacturing
* Laura Knoll, a molecular parasitologist with the Department of Medical Microbiology and Immunology in the School of Medicine.

The four are already tackling important problems. Yu and Keller are researching toxins from molds that contaminate grain; Denes and food microbiologist Amy Wong are developing new ways to protect food during processing. Knoll, the newest hire, will research parasites such as cryptosporidium, which contaminated Milwaukee”s water supply.

Disrupting life cycles of toxic molds

Molds that grow on crops can produce toxins that cause cancer and sicken livestock. Crops contaminated with these toxins cannot be sold as food for humans. Yu and Keller are trying to find out how fungi grow and reproduce on crops, and how to keep them from producing toxins.

“You must know the enemy”s weapons and defenses and how it will react,” explains Yu.

In this case, the enemy is Aspergillus, a group of molds that can grow on many types of grains and nuts. In Wisconsin, Aspergillus periodically causes problems with corn.

When some Aspergillus species reproduce, they produce spores containing a toxin called aflatoxin, considered by the Food and Drug Administration to be a carcinogen. If livestock eat feed contaminated with aflatoxin, they become sick, yield less and may die. Farmers aren”t allowed to sell or feed aflatoxin-contaminated corn.

Yu studies the signals and pathways that steer Aspergillus through its life cycle. He thinks that certain proteins are the key to activating growth and reproduction. Keller also studies Aspergillus – especially its interaction with plants. She”s interested in plant substances that induce or inhibit fungal growth. She thinks she”s identified a natural fatty acid that Aspergillus needs to develop, as well as anti-fungal compounds that plants use to protect themselves.

The scientists believe selective breeding or genetic engineering can be used to disrupt the Aspergillus life cycle. They hope that what they learn about the mechanisms that control the life cycle of Aspergillus will apply to other species-such as Fusarium – that produce major fungal toxins.

The two believe their joint approach is powerful because they cover more ground, studying the entire life cycle of the fungus. Working together lets them share resources and accomplish more in less time, Keller says. Students will also benefit because the two will teach a course together.

Safer surfaces for preparing foods

Keeping food safe in your kitchen requires clean utensils and counters. Industrial food processors also must find ways to guard against pathogens such as Salmonella and E. coli, as well as bacteria that impart bad flavors to foods. They need reliable ways to clean and disinfect the equipment and surfaces they use in handling and packaging food.

Some organisms are resistant to sanitizers, and repeated food preparation cycles may leave tiny food deposits in the nooks and crannies of conveyor belts, blades and other surfaces, says Amy Wong.

“Even with diligent cleaning, there can still be contamination,” she says.

Bacteria that attach to these surfaces may multiply, forming layers of cells called biofilms. Biofilms can contaminate fresh food and cause it to turn foul.

Denes and Wong think that changing the properties of food preparation surfaces can help processors keep their facilities clean and sanitary.

Denes and Wong, who combine their expertise in everything from advising students to conducting research, are finding ways to alter the top layers of materials. The idea is to make it difficult for bacteria to attach to materials. They also hope to incorporate antibacterial agents into surfaces.

Scientists can”t explain exactly how bacteria adhere to surfaces, but changing the characteristics of a surface can make it difficult for bacteria to attach and form colonies. Denes does it with what he calls “dry chemistry.” Instead of using large amounts of toxic chemicals and solvents, he uses cold plasma – an electrically charged gas – to treat surfaces that will be in contact with food.

The plasma interacts with the top layer of even inert surfaces while keeping the material”s basic properties unchanged. Using a patented device, Denes and Wong can modify a surface, and add antibacterial agents to its outer layer. They can also use plasma to decontaminate surfaces, water and air.

The food industry is interested. So is the U.S. Navy, which is considering using plasma technology to remove corrosion-causing biofilms from surfaces on their ships. The research may also lead to new methods for sterilizing and altering hospital surfaces and medical devices.