1. Submitted by :-Mayur Pankhi Saikia
Course:- Bsc Biotechnology
College :-Asian Institute of Management
and Technology
2. I would like to express my sincere respect and
gratitude to Dr Niren Deka Sir,Principal of
Aimt;Dr Monalisha Borah Saikia Mam,our
HOD;our mentor Samson Rosly Sangma Sir
and all the other faculty members.
3. Definitions of microbial growth and culture cell
Phases of microbial growth
Microbial culture
4. Microbial growth is the asexual reproduction
or cell division of a bacteria into two daughter
cells by binary fission.The daughter cells are
genetically identical to the original cell.
Bacterial culture is a method of multiplying
microbial organisms by letting them reproduce
in predetermined culture medium under
controlled laboratory conditions.
5. If we consider a population of microorganisms
introduced into a fresh ,nutrient meduim; they
display four phases of growth.
(a)Lag phase
(b)Log phase
(c)Stationary phase
(d)Death phase
6. Lag phase:-In this phase ,only increase in mass of
bacterial cell size takes place,no incresae in bacterial
cell number.Size of bacteria is maximum in this phase.
Log phase:-Maximum growth of bacterial cell size
takes place in this phase as there is maximum
avalibility of nutrients .Bacterial cell size is minimum
in this phase due to reproduction .This phase is also
known as Exponential phase.
Stationary phase:-Bacterial cell division decreases
to a point that the new cells produced in this phase are
at same rate as number of death of cells.Bacterial cell
death takes place due to release of toxic materials.
Death phase:-Bacterial cell death takes place due to
shortage of nutrition.more accumulation of toxic
materials which also leads to cell death.
7. Microbial culture can be divided into three
types.They are
(a)Batch culture
(b)Fed-batch culture
(c)Contineous culture
(a)Batch culture:-It takes place in a closed system
,nutrients are supplied only once at the
starting,air provided for aerobic microbes.This
culture is used to produce antibiotics.
(b)Fed-batch culture:-Nutrients are provided
again and again without clearing the waste
materials in this phase,but Microbes are added
only once.
8. (c)Contineous culture:-In this phase nutrients are
added contineously and products are also
taken out contineously.They are used to
produce primary metabolites lke
proteins,hormonesetc.
