Mutualism is a relationship between two different organisms in which both benefit from the association. This is the relationship most people think of when they use the word "symbiosis." Although the tiger is a solitary animal, it too has its share of mutualistic relationships that help it survive. Without these relationships, tigers would have become extinct long before the hand of man forced them on the verge they are on today.
A very powerful antibiotic, bacilli is a type of bacteria belonging to the Enterobacteriaceae family. Specifically, Pantoea agglomerans of the bacilli family are helpful by producing a broad spectrum antibiotic andrimid. This kills many harmful bacteria that a tiger may ingest from its prey by blocking a critical step in fatty acid biosynthesis. This helps protect the tiger from such dangers like E. coli and samonella poisoning.
Living in the tiger's gut, coliform bacteria get their energy during the fermenting of lactose, a sugar. During the fermentation process, sugar is broken down into energy or a gas and an acid. Coliform bacteria have an enzyme called galactosidase, which is needed to break down the sugar. The tiger's body alone cannot do this, and without the coliform bacteria, the sugars would simply pass through the tiger's digestive track with no nutritional value.
Bifidobacteria also reside in the tiger's digestive tract. These bacteria feed on the same energy as pathogens carried into the tiger by its food and water. They compete with pathogens for space and resources in the gut, helping to crowd out disease-causing organisms and restore a normal gut ecosystem. All mammals carry Bifidobacteria in their guts. It is essential for survival.
Scientists continue to debate the reason tigers and other large wildcats eat seeds. The digestive system of the cats is far too quick to break down and extract the nutrients in seeds, but all do agree that the digestion does have a "cleaning out" effect on the animals. Tigers eat a variety of seeds in the wild, providing the seeds with a natural fertilizer in scat. The mutualistic relationship is the only one existing between tigers and plant life in the wild.