Litmus Results and Selective and Differential Tests!

We know you were waiting anxiously for the results of the Litmus Test, so we are going to go right into it! Since the suspense is so thrilling, we won't make you wait any longer! 

Litmus Results: 

The pictures above all depict the Litmus Broth specimen after 7 days in the incubator. The purple broth substance that occupied the test tube before has now vanished and turned into curds and whey. Our bacteria sufficiently ferments lactose into an acid and denatures the milk protein Casein, forming a firm curd. The results of the test are interpreted to be an acid curd (determined by the red color at the top) with litmus reduction. 

Exciting, I know right?! Can you handle what happens next...

Selective and Differential Tests: 

We next carried out a series of selective and differential tests in order to identify our bacteria further. One test was to isolate and differentiate gram negative bacilli (Eosin Methylene Blue Agar Test), another tested for salt tolerant gram positive cocci (Mannitol Salt Agar), and finally the last tested the ability to differentiate among gram negative bacilli and to ferment lactose (MacConkey Agar). Using the aseptic technique, we inoculated each of these agars with our unknown "F" bacteria and placed them in the respected incubator. 

Join us next time to see the results of these tests and the meaning behind differential and selective media!