The Koalas (Phascolarctos cinereus) digestive system and how they have adapted Tannin in their diet.
17201576
Tannins are a rich secondary metabolite (Barbehenn, R., & Constabel, C. 2011) that is found in a variety of plants including ferns, monocotyledons and dicotyledons which bind to proteins to form a compound known as tannin protein complex (T-PC). (R. Osawa et al, 1995). This protein complex is not easily broken down by enzymes in the mammalian digestive track. For a native species such as the koala (Phascolarctos cinereus), being an herbivore, they have a selective diet consisting entirely of Eucalyptus foliage. Eucalyptus leaves have a low source of available protein and carbohydrates (C.J. Barker et al, 2013) but contain high levels …show more content…
The well-developed, large caecum is evident for the breakdown of tannins (R. Osawa et al, 1993a) and contains numerous intracellular spaces that increase nutrient and water absorption. (I.D. Hume, 1999). The caecal wall and colon contain specific bacteria known as “tannin-protein-complex-degrading enterobacterium” (T-PCDE) which is responsible for the breakdown of tannins by producing tannase which hydrolyses gallic acid esters such as gallotannin and tannic acid. (R. Osawa et al, 1993a). The bacterium is arranged in the digestive track to maximise the breakdown of the tannin-protein-complexes. The nitrogen found in the protein complex can be utilised in the form of ammonia for microbial protein synthesis however some of the nitrogen is absorbed through the caecal epithelium (R. Osawa et al, 1993a). The ammonia can be used as a nitrogen source for bacteria growth in the hindgut or amino acids in the liver. (I.D. Hume, 1999) Overall the “tannin-protein-complex-degrading enterobacterium” serves as a major advantage in the koala’s digestive track for the selective diet. Without the tannin-protein-complex-degrading enterobacterium, koalas would not be able to utilise proteins bound to tannins which would result in the koala suffering malnutrition (R. Osawa et al, 1993a).
The retention time is extremely long for the koala in the hindgut which increases the digestion of nutrients, decreases the possible loss of microbial protein through faeces and breaks down large contents of fibre which is achieved by the caecum for maximum absorption. Hence, a slow retention time is an advantage to the koala to utilise a low energy and low nutrient diet. (I.D. Hume,
17201576
Tannins are a rich secondary metabolite (Barbehenn, R., & Constabel, C. 2011) that is found in a variety of plants including ferns, monocotyledons and dicotyledons which bind to proteins to form a compound known as tannin protein complex (T-PC). (R. Osawa et al, 1995). This protein complex is not easily broken down by enzymes in the mammalian digestive track. For a native species such as the koala (Phascolarctos cinereus), being an herbivore, they have a selective diet consisting entirely of Eucalyptus foliage. Eucalyptus leaves have a low source of available protein and carbohydrates (C.J. Barker et al, 2013) but contain high levels …show more content…
The well-developed, large caecum is evident for the breakdown of tannins (R. Osawa et al, 1993a) and contains numerous intracellular spaces that increase nutrient and water absorption. (I.D. Hume, 1999). The caecal wall and colon contain specific bacteria known as “tannin-protein-complex-degrading enterobacterium” (T-PCDE) which is responsible for the breakdown of tannins by producing tannase which hydrolyses gallic acid esters such as gallotannin and tannic acid. (R. Osawa et al, 1993a). The bacterium is arranged in the digestive track to maximise the breakdown of the tannin-protein-complexes. The nitrogen found in the protein complex can be utilised in the form of ammonia for microbial protein synthesis however some of the nitrogen is absorbed through the caecal epithelium (R. Osawa et al, 1993a). The ammonia can be used as a nitrogen source for bacteria growth in the hindgut or amino acids in the liver. (I.D. Hume, 1999) Overall the “tannin-protein-complex-degrading enterobacterium” serves as a major advantage in the koala’s digestive track for the selective diet. Without the tannin-protein-complex-degrading enterobacterium, koalas would not be able to utilise proteins bound to tannins which would result in the koala suffering malnutrition (R. Osawa et al, 1993a).
The retention time is extremely long for the koala in the hindgut which increases the digestion of nutrients, decreases the possible loss of microbial protein through faeces and breaks down large contents of fibre which is achieved by the caecum for maximum absorption. Hence, a slow retention time is an advantage to the koala to utilise a low energy and low nutrient diet. (I.D. Hume,