Bacteria Population Growth

The population of microorganisms can grow and create a exponentially increasing number of microorganisms.

Binary Fission
Bacteria will divide and reproduce that way. Most bacteria take 15 minutes to an hour per growth cycle, but slower bacteria like mycobacteria can take up to a few days to divide.

Growth Curve

 * 1) Lag stage: Bacteria adapts to environment, changing metabolism, and not growing very fast.
 * 2) Exponential growth phase: Bacteria grows at an exponential rate. Binary fission happens here. Bacteria in this phase are considered young.
 * 3) Stationary phase: Death rate increases because carrying capacity is reached, to the point where death rate is equal to growth phase. Population stays constant. Bacteria in this phase are considered mature.
 * 4) Death phase: Bacterial growth declines and resources are depleted. Viable bacterial population declines to near zero, but some cells usually remain viable. Bacteria in this phase are considered old.

Counting Colonies
Usually, it is too hard to determine how many bacteria are in a sample because it is really hard to count a billion colonies. A few methods for counting microorganism colonies have been

A serial diltution is used to create less concentrated samples. We count plates that have 25 to 250 colony forming units. Anything more is labled "too numerous to count"