In a recent study done by Markus Egert, a microbiologist at the University of Furtwangen in Germany, pinpointed 362 different species and 82 billion of bacteria that lived within 14 used sponges. This was performed by looking at the DNA and RNA in the samples. Dr. Egert compared the quantity to the same density found in human stool samples. Sponges are the perfect home for bacteria to flourish especially for a particular microbe called, Moraxella osloensis which can cause infections in people who have weak immune systems. Since the bacteria eats fat, it will therefore excrete fat releasing a musty odor that is caused by its metabolism. When the sponges are cleaned (i.e. microwaving them), researchers still found some of the bacteria left in the sponge, so it is recommended to replace them after a week's use instead.
