1. Nutrients: Bacteria require a source of nutrients for energy and to build their cells. These nutrients can include organic molecules like sugars, proteins, and fats, as well as inorganic molecules like minerals and water.

2. Suitable Temperature: Bacteria have an optimal temperature range for growth. They can't survive in extreme temperatures, like very hot or very cold environments. Each bacterial species has its own optimal temperature range.

There are many other factors that influence bacterial growth, such as moisture, pH, and oxygen levels. But nutrients and temperature are the most fundamental.