Education

Putting thinking in a frame

What do your teeth and a ship’s hull have in common? Answer: They’re both eaten by biofilms. Dr. Cristian Picioreanu studies biofilms behavior to catch them in a overall model.

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Teeth, contact lenses, the shipping industry and all sorts of pipes suffer from biofilms, which are thin layers of bacteria, such as the iron-consuming and acid-producing bacteria that causes bio-corrosion on ships.

The same happens on your teeth, where bacteria form plaque. Whenever you eat, you feed your bacterial plaque too, the bacteria converting glucose into acids that demineralize your teeth if you don’t brush them regularly. To gain insight into biofilms, researchers study how bacteria grow. Do they grow in fluffy structures, gathering like snowflakes, or do they grow in thin layers in reactors or on your teeth? And what can toothpaste and chewing gum do to prevent the bacterial attack?

While microbiologists today explain bacteria’s behavior mainly using genetics, chemical engineers like Dr. Cristian Picioreanu prefer to bypass genetics and use a physico-chemical approach. Picioreanu, who works at TU Delft’s Kluyver Laboratory, has made a model based on food diffusion and reaction, bacterial growth, detachment and attachment. “These five processes are relatively well-known and can be put in mathematical formulas. In this way, the biological processes can be cut down to simple chemical reactions,” Picioreanu says.

Flashy

Picioreanu is a theoretical chemical engineer to the bone, his enthusiasm for theoretical research partly influenced by his native country, Romania. “In Romania, the lack of financial resources reflects in poorer experimental research facilities. This was one of the reasons why I chose the theoretical aspects of research during my education.”

Picioreanu made his biofilm model applicable for a well-known chewing gum and toothpaste manufacturer. The model predicts what happens with the acidity level on the tooth surface after people have eaten. For instance, it takes into account reactions when bacteria drop the pH below value 5, gauging how the acidity recovers and the effect of your salvia. And how can we prevent the sour attack?

Dentists, however, already know the conclusion: it%s better to eat candy and drink alcohol and soft drinks all at once, rather than constantly snacking. In this way the neutral acidity level recovers quicker. “But I think taking a sip of water after eating is also a big help in recovering the acidity level,” Picioreanu says

Picioreanu’s flashy simulations on his computer screen show what happens if several kinds of bacteria grow together and when one is in need of food. But he adds an immediate warning: “There’s a lot of esthetically-driven research in microbiology. Researchers show nice colorful pictures like I’m doing right now, but often their interpretation and relevance are meaningless.”

Picioreanu therefore sends his simulations to microbiologists at the Technical University of Denmark, near Copenhagen. “We can check the model with their real experimental data. To optimize my models, I must work together with microbiologists,” he says.

According to Picioreanu, many microbiologists don’t like numbers and equations, but they do know how bacteria are organized. “They put on DVD’s containing gigabytes of data, which Ican compare with my models and which needs to be interpreted.”

Making mathematical models may sound abstract, but for Picioreanu it isn’t. “The person I share an office with at the Kluyver laboratory has a shelf containing three meters of filed data on bacterial growth,” he says. “These data need to be interpreted. Therefore modeling is handy, it puts your thinking in a frame.”

What do your teeth and a ship’s hull have in common? Answer: They’re both eaten by biofilms. Dr. Cristian Picioreanu studies biofilms behavior to catch them in a overall model.

Teeth, contact lenses, the shipping industry and all sorts of pipes suffer from biofilms, which are thin layers of bacteria, such as the iron-consuming and acid-producing bacteria that causes bio-corrosion on ships.

The same happens on your teeth, where bacteria form plaque. Whenever you eat, you feed your bacterial plaque too, the bacteria converting glucose into acids that demineralize your teeth if you don’t brush them regularly. To gain insight into biofilms, researchers study how bacteria grow. Do they grow in fluffy structures, gathering like snowflakes, or do they grow in thin layers in reactors or on your teeth? And what can toothpaste and chewing gum do to prevent the bacterial attack?

While microbiologists today explain bacteria’s behavior mainly using genetics, chemical engineers like Dr. Cristian Picioreanu prefer to bypass genetics and use a physico-chemical approach. Picioreanu, who works at TU Delft’s Kluyver Laboratory, has made a model based on food diffusion and reaction, bacterial growth, detachment and attachment. “These five processes are relatively well-known and can be put in mathematical formulas. In this way, the biological processes can be cut down to simple chemical reactions,” Picioreanu says.

Flashy

Picioreanu is a theoretical chemical engineer to the bone, his enthusiasm for theoretical research partly influenced by his native country, Romania. “In Romania, the lack of financial resources reflects in poorer experimental research facilities. This was one of the reasons why I chose the theoretical aspects of research during my education.”

Picioreanu made his biofilm model applicable for a well-known chewing gum and toothpaste manufacturer. The model predicts what happens with the acidity level on the tooth surface after people have eaten. For instance, it takes into account reactions when bacteria drop the pH below value 5, gauging how the acidity recovers and the effect of your salvia. And how can we prevent the sour attack?

Dentists, however, already know the conclusion: it%s better to eat candy and drink alcohol and soft drinks all at once, rather than constantly snacking. In this way the neutral acidity level recovers quicker. “But I think taking a sip of water after eating is also a big help in recovering the acidity level,” Picioreanu says

Picioreanu’s flashy simulations on his computer screen show what happens if several kinds of bacteria grow together and when one is in need of food. But he adds an immediate warning: “There’s a lot of esthetically-driven research in microbiology. Researchers show nice colorful pictures like I’m doing right now, but often their interpretation and relevance are meaningless.”

Picioreanu therefore sends his simulations to microbiologists at the Technical University of Denmark, near Copenhagen. “We can check the model with their real experimental data. To optimize my models, I must work together with microbiologists,” he says.

According to Picioreanu, many microbiologists don’t like numbers and equations, but they do know how bacteria are organized. “They put on DVD’s containing gigabytes of data, which Ican compare with my models and which needs to be interpreted.”

Making mathematical models may sound abstract, but for Picioreanu it isn’t. “The person I share an office with at the Kluyver laboratory has a shelf containing three meters of filed data on bacterial growth,” he says. “These data need to be interpreted. Therefore modeling is handy, it puts your thinking in a frame.”

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