What bacteria need to grow and multiply
- Food (nutrients)
- Water (moisture)
- Proper temperature.
- Time.
- Air, no air, minimal air.
- Proper acidity (pH)
- Salt levels.
Whereas essentially all eukaryotic organisms require oxygen to thrive, many species of bacteria can grow under anaerobic conditions. Bacteria that require oxygen to grow are called obligate aerobic bacteria.
Bacteria are all around us. Given good growing conditions, a bacterium grows slightly in size or length, new cell wall grows through the center, and the "bug" splits into two daughter cells, each with same genetic material. If the environment is optimum, the two daughter cells may split into four in 20 minutes.
Each type of bacteria grows best in a certain temperature range. Not all bacteria have the same temperature requirements, but most grow best between 40°F and 140°F, which is known as the TEMPERATURE DANGER ZONE.
Some bacteria thrive in extreme heat or cold, while others can survive under highly acidic or extremely salty conditions. Most bacteria that cause disease grow fastest in the temperature range between 41 and 135 degrees F, which is known as THE DANGER ZONE.
Conditions needed for bacterial growth
- Moisture – Bacteria need moisture in order to grow.
- Food – Food provides energy and nutrients for bacteria to grow.
- Time – If provided with the optimum conditions for growth, bacteria can multiply to millions over a small period of time via binary fission .
bacterial growth curve A curve on a graph that shows the changes in size of a bacterial population over time in a culture. The bacteria are cultured in sterile nutrient medium and incubated at the optimum temperature for growth. Samples are removed at intervals and the number of viable bacteria is counted.
Some of the important factors affecting bacterial growth are:
- Nutrition concentration.
- Temperature.
- Gaseous concentration.
- pH.
- Ions and salt concentration.
- Available water.
Warmth, moisture, pH levels and oxygen levels are the four big physical and chemical factors affecting microbial growth. In most buildings, warmth and moisture are the biggest overall issues present.
Bacteria reproduce by binary fission. In this process the bacterium, which is a single cell, divides into two identical daughter cells. Binary fission begins when the DNA of the bacterium divides into two (replicates).
During a bacteria culture test, a sample will be taken from your blood, urine, skin, or other part of your body. The type of sample depends on the location of the suspected infection. The cells in your sample will be taken to a lab and put in a special environment in a lab to encourage cell growth.
Traditionally, the growth curve measurements are performed by measuring the OD of the bacteria, which is related to the cell number, in cuvettes at the wavelength of 600 nm using photometry at desired time points with intervals of 30–60 min [3, 4].
If you are referring to what unit is used in measuring bacteria the answer would most commonly be micrometers (µm).
To find out the number of CFU/ ml in the original sample, the number of colony forming units on the countable plate is multiplied by 1/FDF. This takes into account all of the dilution of the original sample. For the example above, the countable plate had 200 colonies, so there were 200 CFU, and the FDF was 1/4000.
The division time for E. coli and similar microorganisms ranges from 20 minutes to 1 hour. Thus a single E. coli cell, which divides approximately every 30 minutes, can grow into a colony containing 107 – 108 cells in 12 hours (224 = 1.7 × 107).
When a concentrated solution is diluted, the dilution factor may be expressed as the ratio of the concentration of stock solution to the concentration of the diluted solution. As another example, a 2-fold dilution is the same as a dilution factor of 2.
