Part II: Where are Microbes?

In February the inside of a dormitory microwave was swabbed with a RODAC plate. This was for BIOMI 2911 laboratory at Cornell University. For more details see: Part I: Where are Microbes? After incubating the plate for a few days at ~30C a variety of different colonies were observed. There were 4 small round bright yellow colonies, 2 small round light pink colonies, 2 large white colonies with concentration in the center, 2 white round colonies and 1 very tiny round bright pink colony. This diversity of organisms inside a microwave was surprising since it seems that the microwave radiation should be enough to get inhibit growth of microbes.

I decided to isolate and purify the small round light pink colonies since they seemed to be the most interesting. This colony of bacteria contained Gram (-), oxidase positive, catalase positive non-motile rod- shaped bacteria. The bacteria perform aerobic respiration only according to the results of a BCP-glucose shake, which remained purple and had turbity (growth) at the top only. It was postulated that the bacteria belonged to the Pseudomonas genera. However, upon PCR, electrophoresis and BLAST sequencing it deduced that the bacteria was 96% similar to Roseomonas terpenica. Roseomonas is a new genus established in the 1980s that is associated with bacteriemia and other human infections. It seems that it is also radiation resistant since it lives in a microwave... better watch out when microwaving food!