What conditions promote bacterial growth in food?

Bacteria in Food. Letting food sit at room temperature promotes bacterial growth. Bacteria are always present in food, but in very low numbers unless the food has been contaminated by exposure to any type of waste. Bacteria reproduce two to three times per hour, under ideal conditions. Always refrigerate, then heat foods, if there is any chance of bacteria present.
Warmth. In general, keeping food at room temperature for more than 2 hours, allowing food to age so it molds and rots, or cross contamination with other things in the kitchen that have bacteria can promote growth in food.