Identified Unknown Microbe

Providencia stuartii

This week was an exciting week in the lab for me, I finally figured out what my microbe was after conducting a few tests.  The first thing after successfully growing my unknown microbe in a TSA plate was a Gram Stain. Through that process I was able to see that my microbe was a Gram – Bacilli.  Because I was putting my unknown microbe TSA plate in the refrigerator when I left lab, the Oxidase test took a little longer to conduct until my microbes grew more in the incubator.  In the spirit of saving time I ran all the test for Gram Negative Bacilli that were in the lab book. The gelatin test results were negative for gelatin hydrolysis when the inoculated TSB tube turned the liquid into a gel.  The Indole test turned out to be positive for indole when a red ring formed on top in TSB tube.  The Glucose Fermentation test results were positive for acid fermentation, known when the broth turned yellow with no bubble formed in Durham tube. The SIM (Sulfur Reduction, Indole Production, Motility) test results were positive for motility and negative sulfur reduction, when the broth turned a dark yellow/red color.  Once I was able to do the Oxidase Test, it came through as positive for indophenol oxidase when the sterile cotton swab turned from yellow to purple. With the positive results from the positive Oxidase Test and all the other test results and by following the test chart in the lab my unknown microbe’s name is Providencia stuartii .  This whole process of conducting all the tests, reading the results correctly and following the lab chart to figure-out my unknown microbe was awesome!

Before Glucose, SIM, Gelatin, Tryptone

Glucose Test Positive for Acid Fermentation

SIM Positive for Motility, Negative for Sulfur Reduction

Negative Gelatin Hydrolysis

Positive Indole Red Ring