Physical parameters for growth of Bacteria 

Some of the important factors affecting bacterial growth are: 

 1. Temperature 
 2. Gaseous requirement 
 3. pH 
 4. Ions and salt concentration [Osmotic pressure]
 5. Water


Temperature:

Minimum Growth temperature: The lowest temperature at which microbes shows their growth is called minimum growth temperature.
Below minimum temperature cell membrane solidifies and become stiff to transport nutrients in to the cell, hence no growth occurs

Maximum growth temperature: The highest temperature at which microbes shows their growth is known as maximum growth temperature.

There is no growth below minimum and above maximum temperature. 

Optimum growth temperature: That temperature at which bacteria grows rapidly and maximum, is called optimum growth temperature.


Based on temperature they are classified--

1] Psychrophiles (0 - 15 degree C)
2] Mesophiles (20 - 40 degree C)
3] Thermophiles (45- 70 degree C or may be more....)


pH :

pH affects the ionic properties of bacterial cell so it affects the growth of bacteria. 

Most of the bacteria grow at neutral pH (6.5-7.5). However, there are certain bacteria that grow best at acidic or basic pH.

The relationship between pH and bacterial growth is given--


Microorganisms can be placed in one of the following groups based on their optimum pH requirements: 
 1. Neutrophiles grow best at a pH range of 5 to 8. 
 2. Acidophiles grow best at a pH below 5.5. 
 3. Alkaliphiles grow best at a pH above 8.5. 


Gaseous requirement :

Oxygen and carbon-dioxide are important gases that affect the growth of bacteria. 

Aerobic Bacteria: Aerobic bacteria must require O2 for growth. 
For example: Mycobacterium, Bacillus.

Photosynthetic and chemosynthetic bacteria: Require carbon dioxide for growth.

Carbon-dioxide is needed for capnophilic bacteria. Such as Campylobacter, Helicobacter pylori.


Water:

Water is the most essential factor for bacterial growth.

Available water in the culture media determines the rate of metabolic and physiological activities of bacteria. 

Sugar, salts and other substances are dissolved in water and are made available for bacteria. 


Ions and salt concentration/ Osmotic Pressure:

All bacteria requires metal ions such as K+ , Ca ++, Mg++, Fe++, Zn++, Cu++, Mn++ etc. to synthesize enzymes and proteins.

Most bacteria do not require NaCl in media and they can tolerate very low concentration of salt. 

Osmosis: Osmosis is the diffusion of water across a membrane from an area of higher water concentration (lower solute concentration) to lower water concentration (higher solute concentration) without requirement of metabolic energy.

Some halophilic bacteria such as Archeobacteria require high concentration of salt in media. ----- It is balanced with Osmosis process. 




Comments

Post a Comment

Popular posts from this blog

Latex is the cytoplasm of specialized cells, or laticifers, that form an internal secretory system associated with phloem tissues of the vascular system throughout the plant (Thureson-Klein, 1970). The manual lancing of unripe seed capsules is the traditional method for the collection of opium poppy latex.
Read more
 Why Aspirin is Used in cardiovascular complications? Aspirin is often used in the treatment and prevention of cardiovascular complications due to its blood-thinning properties. Low dose of Aspirin is used for the treatment of various CVS complications including MI and High blood Pressure.  Mechanism of Action  Aspirin irreversibly acetylate the serine part of both of the COX enzymes (COX-1, and COX-2). Low dose of Aspirin is used to irreversible blocking of TXA2.  COXs are responsible for the conversion of AA to PGG2 to PGH2 and then Thromboxane A2 (TXA2) which upon binding to the TP (alpha and beta) receptor results in platelet aggregation. and induces blood clotting phenomenon.  For example: Blood clotting in the atherosclerotic plaque results in the development of Angina (unstable).   Inhibition of COXs Results decreased production of TXA2 and thus platelet aggregation does not occurs and Anginal condition may be prevented. thus decreased chances ...
Read more
insomnia   Insomnia is a sleep disorder that makes it difficult to fall asleep and stay asleep. It can cause daytime fatigue, irritability, and difficulty concentrating. There are many different causes of insomnia, including: Stress: Stress can make it difficult to fall asleep and stay asleep. Anxiety: Anxiety can also make it difficult to fall asleep and stay asleep. Depression: Depression can also make it difficult to fall asleep and stay asleep. Medical conditions: Some medical conditions, such as pain, restless legs syndrome, and sleep apnea, can cause insomnia. Medications: Some medications, such as cold medications, can cause insomnia. Poor sleep habits: Poor sleep habits, such as going to bed and waking up at different times each day, can also cause insomnia. There are many different things you can do to treat insomnia, including: Good sleep habits: Establish a regular sleep-wake schedule and stick to it as much as possible, even on weekend...
Read more