Evidence of stress in bacteria associated with long-term preservation of food in the stomach of incubating king penguins (Aptenodytes patagonicus)

Male king penguins are able to conserve food in their stomach for several weeks during their incubation fast. Since a bacterial inhibition could be involved in the process, we investigated the bacterial population of their stomach. Two types of bird were compared, according to whether they conserved (Co) or digested (Dg) food during fasting. Total bacteria and culturable bacteria were studied. In both groups, the food contained a high number of apparently viable bacteria (≥10^sup 7^/ml), but few could be cultured by standard techniques. Culturable bacteria originated mainly from the environment or the upper part of the digestive tract. Neither prevailing bacteria from seawater and fishes nor enteric bacteria cultured. The gastric temperature was around 38°C and the pH of Co bird samples was >4, both conditions favourable for bacterial growth. Morphological characteristics of stressed bacteria (sporulated, deformed or dead cells) were more often found in samples from Co compared to Dg birds. Altogether, these results support the idea that there might be factors inhibiting bacterial growth in king penguins conserving food in their stomach.[PUBLICATION ABSTRACT]