The enzyme that keeps salmon fresh

A bacteria-killing enzyme is helping salmon to keep itself fresh. A new Doctoral dissertation shows how this is possible.

Facts

Enzymes are simple or compound proteins which catalyse reactions in living organisms without being consumed themselves. Lysozymes are enzymes which damage bacterial cell walls.

The work is based on an idea to increase the effectiveness of the animal’s natural immune response to bacteria.

All animals and humans have an enzyme called lysozymes, which are an important part of the immune system. The lysozymes have the ability to "eat" and kill bacterial cell walls.

Indications suggest that this enzyme is different in fish than land animals.

Research Fellow Peter Kyomuhendo, who works at Nofima, has in the course of his Doctoral project studied the properties and structure of such lysozymes from salmon to find and understand the differences in detail.

The findings show that lysozymes in salmon, as opposed to lysozymes in animals, are not stopped by a special immune substance in the bacteria. This can be attributed to differences in the shape and charging of the lysozymes.

Survives boiling

The findings also show that the lysozyme thrives best in temperatures between 0 and 30 °C. At temperatures of over 30 °C, it gradually loses its effect. It also endures boiling and re-emerges after cooling.

"These results are new finds which represent new knowledge about lysozymes in particular, and partly also new knowledge about proteins in general," says Senior Scientist Inge W. Nilsen, who has been Kyomuhendo’s academic supervisor during the Doctoral project.

Peter Kyomuhendo works as a Research Fellow at Nofima Marin in Tromsø. He is educated as a veterinarian in Uganda and has two Master’s degrees – in molecular biology and international fisheries management.

Fish health   Marine biotechnology  

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