I have made some food in my pressure cooker and left it in room temperature for over a week. When I opened it, there was no mold. I threw it out because it might have still been bad, but this got me thinking. Since canning is basically cooking food in a sealed environment, isn't pressure cooking similar when I do not open the pressure cooker? Could the food be left in the pressure cooker  at a room temperature for a longer time, given that I pressure cook it every time I close the lid? 
When you take the pressure cooker off the heat, it's filled with high-temperature, high-pressure steam. As it cools, that steam condenses, leaving a vacuum. Pressure cooker valves are designed to allow air to enter to fill the vacuum (to avoid damaging the pressure cooker, and to make it possible to take the lid off). So it isn't really sealed once it's not at high pressure. 