STRASBOURG, France -- Male king penguins can store swallowed food for weeks by destroying their stomach bacteria, a study shows. The birds' talent for storing undigested food in their stomachs for up to three weeks is unique among higher vertebrates.

This ensures a constant supply of fresh food for their chicks -- but how the penguins do it has been a mystery. Now a new study has led researchers to suspect that the birds produce an antibacterial agent in their digestive tracts. Males use their stomach contents to feed chicks when bad weather delays the female returning with food.

Tests on seven males on possession island in Antarctica that were incubating eggs and conserving food showed their stomach temperatures and acidity were ideal for bacterial growth. In addition, the birds' high-protein diet of fish and squid should have produced an abundance of gastro-intestinal bugs.

But the French team, led by Cecile Thouzeau at the CNRS, France's National Research Organization, in Strasbourg, found this did not happen.

Samples from penguins conserving food contained many more dead or non-viable and malformed bacteria than samples from birds digesting their meals. *** New Scientist *** magazine reported: "The penguins could be suppressing the bacteria with acrylic acid, an antibacterial compound from phytoplankton, which is in turn found in the stomachs of the penguins' prey. But the birds appear to be able to switch on the preservation process, suggesting that they actively release one or more bactericidal agents." (DPA)