Nutrition of crude protein and some bacteria… (Day 180)

Microbiology comparison of the form of growth of Klebsiella and Proteus genus

Today’s Diary Entry is sponsored by Find Pet Boarding

Jumping right into nutrition today with crude protein I am pretty excited to be able to write about this as protein is one of the most important components of a healthy diet. In addition to being one of the most important it is also one of the most expensive components of animal feed. It is also where knowledge of chemistry and biochemistry also comes in handy as proteins are composed of amino acids and each species have their own specific proteins. Protein is the building block of the cell and each cell function is intrinsically linked with the use of proteins. Proteins are complex organic compounds composed of Carbon, Hydrogen, Oxygen, Nitrogen and Sulfur.

Now there are 20 amino acids commonly found as components of protein with plants being able to synthesis these compounds from nitrates within the soil. Not all animals can synthesis all proteins and for that species this gives us the list of Essential Amino Acids (EAA). Some proteins are soluble in water and others are not and most are sensitive to denaturation either by heat of exposure to acid, alcohol, heavy metals or other substances. The most basic way to explain denaturation is to think of what happens to egg white when you heat it and it goes solid, basically all the proteins within it coagulate together.

The quality of protein depends on the type of amino acids it contains and is relative to the species of animal it is being fed to. However there is a need to determine the quantity of protein an animal feed contains and this done by the Kjeldahl method. It determines the crude fibre as this method is based upon the nitrogen content of the feed and so may be influenced by other components containing nitrogen.This is tested by digesting the organic matter in the dry matter of the sample with strong sulphuric acid, the nitrogen is then converted to ammonia which is then titrated against a standard solution and the result used within a calculation to work out the crude protein of the sample. This can be done in a chemistry lab over a day, however professional laboratories have machines such as this which can do the reaction within minutes.

Nutrition machine for the determination of crude protein

Microbiology this afternoon was spent looking at the genus Klebsiella and Proteus in the family Enterbacteriaceae which are facultative pathogens (aka can only cause disease under certain conditions). Though these are both responsible for infections of the urinary tract their form of growth is very different with Proteus having a characteristic swarming growth known as the Rouss phenomenon (seen below).

Microbiology comparison of the form of growth of Klebsiella and Proteus genus
Comparison of the form of growth of Klebsiella and Proteus. Proteus shows swarming growth with Rouss phenomenon

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