More results, Gram Staining an Unknown Bacteria, and That Nasty Tea

More results, gram staining an unknown bacteria, and that nasty tea

Class: Tuesday, September 17, 2013 

Bit of a disappointment today...turns out our bacteria from the air pure culture does not have any magical antibiotic super powers.  All three lines of bacteria grew together over the weekend. 

Both of the white bacteria samples have much wider growth patterns than the orange bacteria, but this is not enough to indicated any antibiotic action going on.  

Last week, Dr. P. gave us an unknown bacterial sample on an agar slant that we will be performing various tests and stains on to observe them under the microscope better.  Our sample is J, to be kept at 25 C. The mystery bacteria is a pale orange color and is shiny, possibly indicating the presence of a capsule or slime layer.  

According to the diagram in the book, our sample grew in a filiform (or even) growth pattern.  It did not spread more than the pattern it was applied with, but filled that line in more fully.  

Our first task today was to transfer some of Bacteria J to a new agar slant which we will grow until Thursday and then store in the fridge for later, in case anything should happen to the current sample.  Juliet was sure to use proper sterile technique and also employed the nifty test-tube-holding-techniques while transferring culture from one test tube to another: 

Double fisting the test tubes: Yes Jess, it is really that awesome

Sterilize by fire! 

Next order of business: Gram stain Bacteria J.  We used the technique last week and are basically experts at this point.  Just a quick recap:

1. Smear bacteria in a drop of water and fix using flame

2. Flood slide with crystal violet and rinse with water after 1 minute

3. Flood slide with Gram's iodine and rinse after 1 minute

4. Use 95% ethanol to decolorize slide

5. Flood smear with safranin color and rinse with water after 1 minute

 Our results? 

Mystery Bacteria J under microscope after
Gram staining

Beautiful! The bacteria took the blue/purple coloring, meaning we know that Bacteria J is Gram positive.  We can also see the shape of the bacteria; they are circular and seem to occur in quads, or little groupings of four bacteria together.

It's tea time! Last week we took a sample from the tea Juliet brought in and made both a streak plate and broth sample of it.  The results are quite intriguing and must be further pursued.  

The streak plate is not particularly exciting, in terms of bacterial growth, but the broth culture has a little more to look at.

Dr. P. was most intrigued that there seems to be some anaerobic growth going on here.  That's why the streak plate has very little, but the broth culture as some very healthy fuzzy bacteria in it, growing in the culture medium, not on top of it.  

In order to gain more understanding, we must of course test the bacteria's ability to grow even more.  We took a sample of the bacterial growing on the streak plate and put it into a broth culture.  We then took a sample of the fuzzy bacteria growing in the broth culture and put it on a streak plate.  I hope our arrows don't get too confusing here!

Tea bacteria sample moved from the broth
to an Petri dish

Tea bacteria sample moved from plate to the broth