The document outlines the basic requirements for microbial growth, including water, temperature, light, oxygen, pH, food, and osmotic pressure. It states that microbes require 25-40% water content and cannot grow below 3% water content. It also classifies microbes based on temperature preferences as psychrophiles, mesophiles, thermophiles, and hyperthermophiles. The document notes that most bacteria grow best in a pH range of 6.5-7.5 and consume many of the same foods that humans eat. Finally, it mentions that microbial growth proceeds best under ideal osmotic pressure conditions and some can tolerate high salt concentrations.

1. BASIC REQUIREMENTS OF
MICROBIAL GROWTH
By : Mustafa Jamal

2. BASIC REQUIREMENTS OF MICROBIAL
GROWTH
the basic requirements for microbes to grow in the
environment
1.Water
2. Temperature
3. Light
4. Oxygen
5. pH Favorable
6. Food
7. Favorable osmotic pressure

3. Water
Bacteria Need a Source of Water
About 70 percent of a bacterial cell is consist of water.
For multicellular organisms such as humans water
must be ingested. Single-celled bacteria ideally water
content of 25-40 % is requirements for optimal grow of
microbial in medium and no active take place if the
water content is less than 3 %
BASIC REQUIREMENTS OF MICROBIAL
GROWTH

4. Temperature
On the basis of preferred temperature ranges, microbes are
classified as psychrophiles (cold-living), mesophiles (moderate-
temperature-loving), and thermophiles (heat-loving).
 Psychrophiles can grow at 0° C but optimum is about 15° C.
 Psychrotrophs can grow at 0° C also but optimum is 20 - 30° C –
important in food spoilage.
 Mesophiles grow best at moderate around 37° C – many
pathogens fall in this category.
 Thermophiles have a growth optimum at around 60° C.
 Hyperthermophiles have growth optima of 80° C or higher
BASIC REQUIREMENTS OF MICROBIAL
GROWTH

5. Temperature
BASIC REQUIREMENTS OF MICROBIAL
GROWTH

6. Light
microbial growth and multiplication is favored
by darkness or dim light
bright light conditions on the other hand
discourage growth and multiplication
in fact direct sun rays can kill most bacteria
the sunshine will help to have better personal
BASIC REQUIREMENTS OF MICROBIAL
GROWTH

7. Oxygen
 Obligate aerobes – require O2
 Facultative anaerobes – can use O2 but
also grow without it
 Obligate anaerobes – die in the presence
of O2
BASIC REQUIREMENTS OF MICROBIAL
GROWTH

8. pHFavorable
most bacteria grow in the
range of pH near neutrality;
usually
between 6.5 -7.5; as bacteria
grow, their metabolic activities
change the pH of their living
environment
BASIC REQUIREMENTS OF MICROBIAL
GROWTH

9. Food
they consume many of the food that we
eat .limiting the amount of food available
to microbial population will limit their
growth
for example through the practice of
cleaning can greatly control the growth
of many disease causing and other
microbes
BASIC REQUIREMENTS OF MICROBIAL
GROWTH

10. Pressure
Microbial growth proceeds best when the
osmotic pressure is ideal.
Microorganisms that live in marine
environments can tolerate high salt
concentrations
These organisms are said to be halophilic.
They include diatoms and dinoflagellates, two
types of unicellular algae
There are many other species of halophilic
bacteria, fungi, protozoa, and algae.
BASIC REQUIREMENTS OF MICROBIAL
GROWTH

11. Thank you
for your attention