Four Conditions For Bacterial Growth

Bacteria have certain requirements in order to grow individual cells and bacterial populations of many millions of cells. With appropriate nutrients and other factors, an individual bacterial cell can divide and result in many millions or billions of cells. When nutrients become scarce, the bacterial population begins to die.

Nutrients

Different bacteria have different nutrient requirements for growth. In general, all bacteria require the elements carbon, nitrogen, hydrogen and phosphorus, among other elements. The production of amino acids, nucleotides and other organic molecules depend on these very basic elements as building blocks. Microbial growth becomes possible if there's a nutrient concentration in a given microenvironment that contains these elements. When these nutrients expire, the bacteria either die or move to a different location with available nutrients.

Temperature

The temperature in an environment can control microbial growth, even in the case of high nutrient availability. Grouping bacteria by optimal temperature is common. The major temperature groups include psychrophiles, mesophiles, thermophiles and hyperthermophiles. According to Carleton College, psychrophiles prefer a relatively cold environment, growing best at or below 59 degrees F; mesophiles grow best at an average temperature of 68 to 104 degrees F. The human body, at 98.6 degrees F, harbors many mesophiles. Thermophiles exist at much hotter temperatures of 113 to 176 degrees F; and hyperthermophiles live in some of the most extreme environments on Earth--some hyperthermophiles can survive in temperatures up to 212 degrees F.

Energy Metabolism

Energy sources vary widely among bacteria. Some types of bacteria can use different sources of energy, depending on the environment. Other bacteria require a very specific energy source, and can use no other. Aerobic bacteria use oxygen as a final electron acceptor to create energy in the form of adenosine triphosphate, or ATP. Without ATP in the cell, no other cell processes can take place. In anaerobic bacteria that can't use oxygen, organic molecules such as sugars act as the final electron acceptor, a process more commonly known as fermentation.

PH

Bacteria rely on the environment to have a certain acidity, or lack thereof, for survival. PH is a measurement of potential hydrogen, or the amount of protons in a solution. The more free hydrogen, the lower the pH, and the more acidic the solution. Categories for pH preference among organisms include acidophiles, neutrophiles and alkaliphiles. Acidophiles prefer environments with a pH in the acidic range, or below 7. Neutrophiles, as the name implies, grow best at a neutral pH of 7. Alkaliphiles experience the best growth at pH in the basic range, or above 7.