Inter-Specific Variations in the gastrointestinal microbiota of penguins. Inter-Specific Variations in the gastrointestinal microbiota of penguins

Gastrointestinal (GI) microbiota has a profound influence on the nutritional, physiological, immunological and metabolic processes of the host, playing a significant role in energy harvest, fat metabolism, secretion and synthesis of nutrients, vitamins, amino acids and the production of short chain fatty acids from the diet. However, despite the enormous amount of data available on the importance of microbes in other vertebrate species (especially mammals), information on the GI microbiotas of seabirds remain incomplete. As with many seabirds, penguins have a unique digestive physiology that enables them to store large reserves of adipose tissue (fat), protein and lipids in advance of long periods of fasting during the breeding season and moult. Our study used quantitative real time polymerase chain reaction (qPCR) and 16S rRNA gene pyrosequencing to characterise the inter-specific variations in the gastrointestinal microbiota of four penguin species: the king (Aptenodytes patagonicus), gentoo (Pygoscelis papua), macaroni (Eudyptes chrysolophus) and little penguin (Eudyptula minor). The qPCR results indicated that there were significant differences in the abundance of the major phyla Firmicutes, Bacteroides, Actinobacteria and Proteobacteria. A total of 132,340, 18,336, 6,324 and 4,826 near full-length 16S rRNA gene sequences were amplified from faecal samples collected from king, gentoo, macaroni and little penguins respectively. A total of 13 phyla were identified with; Firmicutes, Bacteroidetes, Proteobacteria and Fusobacteria dominating the composition. Although all four species of penguin are dominated by similar phyla, there are major differences in the proportion of the different phyla. Gentoo penguins were dominated by Fusobacteria (55%), Firmicutes (18%), Proteobacteria (18%) and Bacteroidetes (7%). In king penguins, Firmicutes (48%), Fusobacteria (24%) and Bacteroidetes (18%) dominate. The dominant phyla in little penguins were Proteobacteria (30%), Firmicutes (24%), Bacteroidetes (22%), Planctomycetes (11%) and Actinobacteria (7%). Whilst in macaroni penguins, Firmicutes (45%), Proteobacteria (29%) and Bacteroidetes (19%) dominate (Figure 2).The presence of known human/veterinary pathogens; Campylobacter, Helicobacter, Prevotella, Veillonella, Erysipelotrichaceae, Neisseria and Mycoplasma were also identified. However, their role in disease in penguins is unknown. To our knowledge, this is the first study to provide an in depth investigation of the gastrointestinal microbiota of penguins that shows the composition of the gastrointestinal microbiota between all species of penguin to be significantly different