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In today’s lab, we observed the Rainbow agar 0157 plate, EMB plates and Hektoen agar plates incubated in last lab. The colonies growing on the Rainbow agar 0157 plate are red color which represents a positive beta-glucuronidase test results. Non-pathogenic strains of E.coli generally have a positive beta-glucuronidase test results. So luckily we don’t have pathogenic E.coli growing on our spinach!

On the EMB plate, we didn’t see a very distinctive morphology. We saw a pink smear on the agar plate.

We did three different dilutions on the Hektoen agar plates and there’s only orange colonies growing on the highest dilution. Comparing day 21 and day 14 results, less orange colonies grow on day 21 and this is probably because some E.coli ran out of nutrient and died.

Last lab, we digested Plasmid DNA with EcoR1 at room temperature and 37 degree Celsius. In this lab, we ran the Agarose Gel Electrophoresis of the undigested Plasmid DNA, digested Plasmid DNA with EcoR1 at room temperature and 37 degree Celsius at 110V for one hour. We can see that DNA migrated. However, there’s nothing shown on the second column and this maybe because I didn’t add enough Plasmid DNA.

This week we finished the exciting Lab 4 which is the isolation of E.coli plasmid DNA! We use the GeneJET Plasmid Miniprep Kit to isolate the E.coli plasmid DNA. The basic principle is that the size and conformation (degree of supercoiling) is different for the chromosomal DNA and the plasmid DNA. The solutions required for the isolation are re-suspension solution, lysis solution, neutralization solution, wash solution-contains 80% ethanol, elution buffer, spin column with silica-based membrane and microfuge tubes. In each step, we used the centrifuge to do the centrifugation of the microfuge tubes.

Eventually, we collected the flow-through in the micro-centrifuge tube which is the plasmid DNA of E.coli.

In this lab, we also did the plate count for the lab 3 incubation of bacteria using the pour plate methods.

Lastly, we did the “Day 1” for lab 6. My group’s leafy green vegetable is spinach. It seemed that we were making nutritious smoothie in the lab! LOL

Haha! Actually we were making homogeneous sample solutions and then we used it as the 10^-1 to make a series dilution.

Great! Let’s see the incubation results after 2 weeks.