House dust full of bacteria
A genetic analysis revealed that the average household had more than 2,000 species of fungi. The types of fungus found though depended on the home's location, suggesting these minute organisms are drifting in from outside.
The researchers also discovered an average 7,000 different types of bacteria per household. But the species varied according to whether men or women were the main residents or whether they lived with cats or dogs.
Although the study was carried out in the US, the scientists say the findings are also relevant around the world.