Streaking Plates & Creating More Stains

Today in lab we took our environmental sample and our unknown sample and placed the bacterias in test tubes containing broth. We fulfilled this procedure using the aseptic technique. After correctly transferring the bacteria, we labeled the tubes and placed them in the incubator at 25 degrees Celsius for the next class.

Following our lab books instructions for 'Examination of Bacteria and Creating A Pure Culture' we than made a streak plate of our unknown bacteria sample ('L'). This is so we could more closely examine the unknown and to perform more tests on it!

We also did a simple stain of the unknown bacteria 'L' (the slant which we took out of refrigerator) in a Methylene Blue stain. We followed the exact stain procedure as the one in the last blog post. It had to sit on the slide for a good minute before we washed it off with distilled water. We did the exact same Methylene Blue stain on our Environmental sample (in this case my throat swab!).

Staining With Methylene Blue 

Isolating the Bacteria into An Agar Plate

Classmate Preparing To Take A Swab From The Professor's Throat

After we did slides and viewed both the environmental & unknown sample under microscopes. We also made a new isolation of the unknown & environmental sample in peteri dishes (with agar). We also placed both the unknown and the environmental into broth tubes by using the aseptic technique. This ensures no contamination as we sterilize the loop between each transfer. We also started testing the Motility of our environmental & unknown samples. We took an inoculating needle and sterilized it in the flame of a Bunsen burner. Once sterilized, we used the inoculating needle to transfer some bacteria into a semisolid agar (this means there is .4% agar rather than 1.5%) and let it incubate for 24 to 48 hours at 25°C.

A classmate, Monica, then took a swab of our Professor's throat. She used a tongue depressor to make sure his tongue stayed out of the way and simultaneously used a swab over his tonsils.  It was really cool! We than rubbed the swab sample over red blood cells and placed two antibiotics in it: a small dose of Bactratin and a small dose of Penicillin (they were placed only in two concentrated areas on opposite ends of the dish). If the bacteria is only killed by the penicillin it is a normal bacteria that all human's throats contain but if it is also killed by the Bactratin it is Streptococcus pyogenes, which means the professor has strep throat! We currently left it in the incubator to grow!

Than our Professor used a T4 Phage in a peteri dish over a bacteria. He used a micro pipette to drop .5ml in one section of the dish and 1.0ml in another section. He then spelled out his initials: JAP in the center of the dish. (Although it is invisible at this point because the bacteria has not grown yet.) We than placed it in the incubator! Come back in two days to see the results of the T4 & the Professor's throat sample!

Annie B