What Three Conditions Are Ideal for Bacteria to Grow?

By Stacy Taylor

Bacterial Nutrient Needs

While different types of bacteria have varying diets, they all require nutrients to provide energy. Energy is necessary to fuel work inside the cell. Many bacteria use the carbon, nitrogen, phosphorus or sulfur from their nutrient source to produce energy. These elements are broken down during cellular respiration to make the energy molecule, adenosine triphosphate. Some bacteria get their energy from sunlight using unique metabolic methods. Scientists who grow bacteria in a laboratory use concentrated growth media containing readily available carbon, nitrogen, sulfur and phosphorus along with many vitamins and minerals. They choose different media depending on the preference of the bacteria they wish to grow.

Bacteria Need a Source of Water

Approximately 70 percent of a bacterial cell is composed of water. For multicellular organisms such as humans, water must be ingested. Single-celled bacteria must exist in an environment with enough available water for the bacteria to absorb it through their cell membranes.

Environmental Conditions for Bacteria

Outside of nutrients and water, each species of bacteria has a specific environmental preference. Preferences include the best pH, temperature range, amount of light, concentration of gases such as oxygen and carbon dioxide, and amount of pressure present. The pH conditions may be acidic with pH levels from 6 to 1; alkaline with pH levels from 8 to 14; or somewhat neutral with a pH of around 7. Many bacteria grow well at or near a neutral pH of 6.0 to 8.0. Temperatures also vary, with many able to grow between 5 degrees Celsius (40 degrees Fahrenheit) and 50 degrees Celsius (104 degrees Fahrenheit). Some bacteria that need oxygen for their metabolism can use the 10 to 12 percent available in the atmosphere, but that amount of oxygen can be lethal to other bacteria. Other species require an oxygen-free environment, or a high level of carbon dioxide. Environmental pressure such as osmotic pressure and atmospheric pressure are also important.

Bacteria Adapt to Varying Conditions

Bacterial species have specific needs for growth, but they are flexible. They can adapt to conditions that are not ideal as long as they are close to their preference. Although ideal conditions are not the same for each bacterial species, the conditions under which a bacterium is observed and collected should be replicated as closely as possible to help it grow in the laboratory.

About the Author

Stacy Taylor is an accomplished scientist, educator and writer. Taylor has a bachelor’s degree in human biology, a master’s degree in microbiology and additional graduate work in biomedicine and public health. Taylor has been teaching college biology courses since 1998.