presentation on microbial growth

1. MICROBIAL
GROWTH

2. CONTENT
*What are microbes ?
*How do they REPRODUCE ?
*Growth curve.
*Factors affecting growth of
microbes.

3. What are microbes?
Microbes or "microscopic organisms"is a
living thing that is too small to be seen
with the naked eyes. We need to use
microscope to see them.
It is used to describe many different types
of life forms, with dramatically different
sizes and characteristics:-

5. How do
they
reproduce?
They reproduce by binary
fission.

6. Growth curve
The growth of microorganisms
reproducing by binary fission can be
plotted as the logarithm of the no. of
viable cells versus incubation time.
The growth curve has four distinct
parts:-
*Lag phase
*Log phase
*Stationary phase
*Death phase

7. Lag phase-Making new enzymes in response to new
medium.
Log phase-Exponential growth
-Desired for production of products
-Most sensitive to drugs and radiation
during this period.
Stationary phase:-nutrients becoming limiting or
products becoming toxic.
Death phase=Division rate
Death phase:-Death exceeds division

9. Factors affecting growth of
microbes
A variety of factors may affect microbial growth,
which are :-
#pH
#Temperature
#Oxygen concentration
#pressure
#Radiation

10. pH
It is a dramatically affect microbial growth each
species has a definite pH growth range and pH
growth optimum.
#Acidophilus grows in pH 0-5.5
#Neutrophils grows in pH 5.5-8.0
#Alkalophiles grows in pH 8-11.5
#Extreme alkalophiles grows in pH 11.5-14.

11. The most effecting factor for microbial growth is
temperature.It is well known that temperature affects
the rate of enzyme catalyzed reaction.Hence,growth can
also be related with with temperature.As the
temperature rises from the slow temperature the rate of
catalysis increases to that absorb from the optimum
temperature.
On the basis of optimum temperature for growth,the
microorganisms are broadly divided into three groups
Temperature

12. psychrophiles:-Cold loving.
Mesophiles:-Moderate
temperature loving.
Thermophiles:-Heat
loving.
Each has a minimum,
optimum and maximum
growth temperature.

13. Oxygen concentration
Oxygen is most important element for microbial
growth because respiration and metabolism need
oxygen.
An organisms able to grow in presence or oxygen is
aerobic,where one that grow in absence of Oxygen
is anaerobic.

14. Pressure
Organiam that spend their lives on the
surface of water are always subjected to a
Pressure of 1atm and are never affected
significantly by pressure.
Many prokaryotic organism lice in the deep
sea where the hydrostatic pressure can reach
600 to 100 atm and temperature is about 2
-3°c.

15. Radiation
As the wavelength of electromagnetic radiation
decreases,the energy of the radiation increases
alpha rays and x rays are much more energetic
than visible rays or infrared waves.
A variety of changes in cells are due to ionizing
radiation,it breaks H-bond,destroy ring
structure.