Can I Put Bacteria at 4 C Then Grow Them Again

May 14, 2022 Post a Comment

With respect to humans, the term growth refers to an increase in size; for example, going from a tiny newborn babe to a large adult.
Although leaner do increase in size before cell sectionalization, bacterial growth refers to an increase in the number of organisms rather than an increase in their size.
Bacterial growth can be divers as an orderly increment of all the chemical components of the jail cell.
Cell multiplication is a consequence of growth that leads to an increment in the number of bacteria making up a population or culture.
Well-nigh bacteria dissever by binary fission in which the bacteria undergo cell division to produce two girl cells identical to the parent cell.
Bacterial growth can be equated to cell number: one bacterium divides into 2, these ii produce four, and then eight, and so on.

Generation fourth dimension

The growth rate of a bacterium is measured by measuring the change in bacterial number per unit time.
Generation time is the time required for a bacterium to give rise to two daughter cells under optimum conditions.
The generation time for most of the pathogenic leaner, such equally E. coli, is nearly xx minutes.
The generation time is longer (i.e., 20 hours) for Mycobacterium tuberculosis and longest (i.e., 20 days) for Grand. leprae.
A bacterium replicates and multiplies rapidly producing millions of cells within 24 hours.

Factors Affecting Growth of Bacteria

The growth of microorganisms in the body, in nature, or in the laboratory is greatly influenced by temperature pH, wet content, available nutrients, and the characteristics of other organisms nowadays.

Oxygen

Leaner on the basis of their oxygen requirements can exist classified broadly into aerobic and anaerobic bacteria.

Aerobic leaner:

They require oxygen for their growth. They may be:

Obligate aerobes—which tin can abound only in the presence of oxygen (e.g., P. aeruginosa).
Facultative aerobes—which are ordinary aerobes only can besides grow without oxygen (e.m., E. coli). About of the pathogenic leaner are facultative aerobes.
Microaerophilic bacteria—those leaner that can grow in the presence of depression oxygen and in the presence of low (four%) concentration of carbon dioxide (due east.thou., Campylobacter jejuni).
Some fermentative organisms (east.g., Lactobacillus plantarum) are aerotolerant but do not contain the enzyme catalase or superoxide dismutase. Oxygen is not reduced, and therefore hydrogen peroxide (H2O2) and nascent oxygen (O2) are not produced.

Anaerobic bacteria:

Obligate anaerobes are the bacteria that tin can grow only in the absence of oxygen (e.g., Clostridium botulinum, Clostridium tetani, etc.).
These leaner lack superoxide dismutase and catalase; hence oxygen is lethal to these organisms.

Carbon dioxide

The organisms that require higher amounts of carbon dioxide (CO₂) for their growth are called capnophilic leaner.
They grow well in the presence of 5–10% CO_two and fifteen% O_two.
In candle jar, 3% CO₂ tin can exist achieved.
Examples of such leaner include H. influenzae, Brucella abortus, etc.

Temperature

The optimum temperature for most of the pathogenic bacteria is 37^oC.

The optimal temperature, even so, is variable; depending on their temperature range, growth of bacteria is grouped as follows:

Psychrophiles: These bacteria are cold loving microbes that grow within a temperature range of 0–20^o About of soil and water saprophytes belong to this group.
Mesophiles: These are moderate temperature loving microbes that grow between 25^oC and 40^o Well-nigh of pathogenic bacteria vest to this group.
Thermophiles: These are rut loving microbes. They can grow at a high temperature range of 55–80^o B. stearothermophilus is an example.

pH

Well-nigh pathogenic leaner grow between pH 7.2 and seven.6.
Very few bacteria, such as lactobacilli, tin can grow at acidic pH below iv.0.
Many food items, such equally pickles and cheese, are prevented from spoilage by acids produced during fermentation.
Five. cholerae is an instance of the bacteria that can grow at an alkaline metal (8.2–8.ix) pH.

Light

Depending on the source of energy leaner make utilise of, they may be classified as

Phototrophs (bacteria deriving energy from sunlight)
Chemotrophs (bacteria deriving energy from chemical sources).

Osmotic pressure

Microbes obtain almost all their nutrients in solution from surrounding water.
Hence factors such equally osmotic pressure and common salt concentration of the solution touch the growth of bacteria.
Bacteria past virtue of mechanical strength of their jail cell wall are able to withstand a wide range of external osmotic variations.
Organisms requiring high osmotic pressures are chosen osmophilic bacteria.
Sudden exposure of bacteria to hypertonic solution may cause osmotic withdrawal of water, leading to osmotic shrinkage of the protoplasm (plasmolysis).
On the other hand, sudden transfer of bacteria from concentrated solution to distilled water may cause excessive imbibition of water leading to swelling and bursting of jail cell ( plasmoptysis).

References

Parija S.C. (2012). Textbook of Microbiology & Immunology.(2 ed.). Bharat: Elsevier Republic of india.
Engelkirk, P. M., Duben-Engelkirk, J. L., & Burton, G. R. W. (2011). Burton'south microbiology for the wellness sciences. Philadelphia: Wolters Kluwer Wellness/Lippincott Williams & Wilkins.
Sastry A.S. & Bhat S.1000. (2016). Essentials of Medical Microbiology. New Delhi : Jaypee Brothers Medical Publishers.
Trivedi P.C., Pandey Due south, and Bhadauria South. (2010). Textbook of Microbiology. Arrow Publishers; Outset edition
Murray, P. R., Rosenthal, Grand. S., & Pfaller, M. A. (2013). Medical microbiology. Philadelphia: Elsevier/Saunders.