Basic requirements of microbial growth

BASIC REQUIREMENTS OF

MICROBIAL GROWTH

By : Mustafa Jamal

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

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 %


GROWTH

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


GROWTH

Temperature


GROWTH

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


GROWTH

Oxygen

Obligate aerobes – require O2

Facultative anaerobes – can use O2 but

also grow without it

Obligate anaerobes – die in the presence

of O2


GROWTH

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


GROWTH

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


GROWTH

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.


GROWTH

Thank you

for your attention

Basic requirements of microbial growth

Health & Medicine

Transcript of Basic requirements of microbial growth