kskerr
09-26-2006, 12:10 AM
AKA I am tired and not feeling like working on the assignment I should be working on.
Today's microbe genre is Propionibacterium. There are two main groups these bacteria fall into, a small group of human skin guess you could call pathogens, they cause acne. They grow at around 37 C (human body temp for those who aren't up on their metric) and tend to be longer than the other group. The other group consists of dairy isolates (bacteria isolated from dairy products), these bugs are the causative agent of Swiss cheese. I personally consider them to be cheese pathogens because I do not like swiss cheese. They ferment glucose (and other sugars) into propionic acid (hense their name) which is a three carbon acid (pro = three), they also produce some acetic acid (the stuff in vinegar) and carbon dioxide. The acid (specifically propionic which they make the most of) and the carbon dioxide are what cause the swiss cheese's unique charactaristics, the taste (if you can call it taste) is produced by the acid and the holes by trapped pockets of carbon dioxide. The acid also acts to inhibit some types of fungus, but definately not all since I have seen fungus on swiss cheese. The acidity in general inhibits the growth of spoilage organisms which is why swiss cheese can have a long shelf life.
These bacteria are anaerobic (they do not grow in the presense of oxygen), and the dairy isolates like it about 30-32 C, which is warm but not too hot (somewhere in the 80's I think). The dairy isolates also tend to be very short rods that look rather like cocci (sphere shape), they often form an almost lacey pattern under the scope (I would know, I have looked at hundreds slides of them). In the Gram reaction (aka Gram Stain) they stain purple, or positive. This is because they have a thick cell wall that traps the purple dye inside so it is not washed away as it is in the Gram negatives (note Gram is capitolized, the staining technique was developed by Dr. Gram). Perhaps there will be more on Gram staining some other time if anyone cares or I am bored and have time. These cells are non-motile, meaning they lack flagella and cilia and therefore cannot swim/move.
This bug was my first research organism as a grad student and almost ended up as my research organism for my graduate career, thankfully it worked out such that I found an even better one to play with.
Today's microbe genre is Propionibacterium. There are two main groups these bacteria fall into, a small group of human skin guess you could call pathogens, they cause acne. They grow at around 37 C (human body temp for those who aren't up on their metric) and tend to be longer than the other group. The other group consists of dairy isolates (bacteria isolated from dairy products), these bugs are the causative agent of Swiss cheese. I personally consider them to be cheese pathogens because I do not like swiss cheese. They ferment glucose (and other sugars) into propionic acid (hense their name) which is a three carbon acid (pro = three), they also produce some acetic acid (the stuff in vinegar) and carbon dioxide. The acid (specifically propionic which they make the most of) and the carbon dioxide are what cause the swiss cheese's unique charactaristics, the taste (if you can call it taste) is produced by the acid and the holes by trapped pockets of carbon dioxide. The acid also acts to inhibit some types of fungus, but definately not all since I have seen fungus on swiss cheese. The acidity in general inhibits the growth of spoilage organisms which is why swiss cheese can have a long shelf life.
These bacteria are anaerobic (they do not grow in the presense of oxygen), and the dairy isolates like it about 30-32 C, which is warm but not too hot (somewhere in the 80's I think). The dairy isolates also tend to be very short rods that look rather like cocci (sphere shape), they often form an almost lacey pattern under the scope (I would know, I have looked at hundreds slides of them). In the Gram reaction (aka Gram Stain) they stain purple, or positive. This is because they have a thick cell wall that traps the purple dye inside so it is not washed away as it is in the Gram negatives (note Gram is capitolized, the staining technique was developed by Dr. Gram). Perhaps there will be more on Gram staining some other time if anyone cares or I am bored and have time. These cells are non-motile, meaning they lack flagella and cilia and therefore cannot swim/move.
This bug was my first research organism as a grad student and almost ended up as my research organism for my graduate career, thankfully it worked out such that I found an even better one to play with.