This week I made 20 plates of agar. Eight plates were made 4pH and the rest (12) were just normal plates which sit at a neutral 7pH. I plan on growing serratia on five of the pH plates, and five of the normal plates. Then I will transfer three of the plain plates to pH plates, and the other two plain plates to another two plain plates, and the pH plates will all be transferred to plain plates. All the plates will then get a disk of the antibiotic tetracycline in the middle. After letting the bacteria grow at room temperature for two days, there was finally enough bacteria to transfer. I was shocked to see that the serratia on the normal plates was pink, and the bacteria on the pH plates was white! I find this very interesting that perhaps pH plays a role on pigment, and after doing research I found that serratia actually grows best at a round 8.5-9 pH. Since I now know this I wonder if antibiotic effectiveness has to do with the level of pigmentation. On Friday I make 30 more plates, this time making three plates at 5, 6, 7, 8, and 9 pH, and the rest regular. I also checked my plates for any rings around the antibiotic, there was nothing today so I will check again Tuesday.
Thursday, May 25, 2017
This week I focused on research, I’m still very interested in antibiotic resistance and wanted to build off of what I have done the past two years. The past two years I focused on testing pH on E.coli and found that when E.coli was grown on a 4pH agar base the antibiotic (penicillin) was able to kill some of the bacteria. That’s why this year I have decided to see if the same method works on serratia, which is now resistant to tetracycline. Next week I will pour the plates, and test it out.