The document summarizes bacterial growth kinetics and growth curves. It discusses: 1) Bacterial growth occurs through binary fission, where a single cell divides into two identical cells. This allows bacterial populations to increase exponentially over time. 2) A bacterial growth curve consists of four phases - lag phase, logarithmic/exponential phase, stationary phase, and decline phase - with transitions between each. The logarithmic phase sees the fastest growth rate. 3) Generation time is the time it takes for a bacterial population to double and varies between species and growth conditions. The reciprocal of generation time is the growth rate constant. Common generation times range from 15 minutes to 24 hours.

1. VEER JIJAMATA TECHNOLOGICAL
INSTITUTE
DEPARTMENT OF ENVIRONMENTAL
ENGINEERING
M.TECH (FIRST YEAR)
SUBJECT-ENVIRONMENTAL CHEMISTRY &
MICROBIOLOGY
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2. TOPIC NAME
KINETICS OF BIOLOGICAL GROWTH, BACTERIAL
GROWTH IN TERMS OF NUMBERSAND MASS, GROWTH
CURVE
PRESENTED BY
ONKAR NANDKUMAR SANGAR
UNDER GUIDANCE OF
DR. P. B. BHAVE
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3. INTRODUCTION
• Cell growth implies increase in its mass and physical size controlled
by physical, biological and chemical environments.
• Microbial growth is quantified by increase inhe macromolecular and
chemical constituents of the cell and growth pattern of each microbe is
unique.
• Growth kinetics is an autocatalytic reaction which implies that the rate
of growth is directly proportional to the concentration of cell.
• Microbial growth kinetics explains the relationship between the
specific growth rate of a microbe and its substrate concentration. 3

4. BIOLOGICAL GROWTH
• Biological exponential growth is the unrestricted growth of a population of
organisms, occurring when resources in its habitat are unlimited.
• Most commonly apparent in species that reproduce quickly and asexually,
like bacteria, exponential growth is intuitive from the fact that each organism
can divide and produce two copies of itself.
• Each descendent bacterium can itself divide, again doubling the population
size. The bacterium Escherichia coli, under optimal conditions, may divide
as often as twice per hour.
• Left unrestricted, a colony would cover the Earth's surface in less than a
day.
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5. KINETICS OF BIOLOGICAL GROWTH IN
ANIMAL
• The growth of animals is more restricted
in time than is that of plants.
• but cell division is more generally
distributed throughout the body of the
organism.
• Although the rate of cell division differs in
different regions, the capacity for cell
division is widely distributed in the
developing embryo.
• Cell division and size increase continue,
however, even after increase in total body
size no longer occurs. Because these events
are balanced by cell death
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6. • Lag phase
The lag phase which occurs immediately after inoculation
and persists until the cells have acclimated to their new
environment.
• Exponential Growth phase
Exponential phase, during which time cell growth
proceeds at an exponential rate (indicated by a straight
line on the semi-log plot).
• Deceleration phase
when essential nutrients are depleted or toxic products
begin to accumulate. 6

7. • Stationary phase
during which time the net cell growth is approximately
zero.
• Death phase
where some cells loose viability or are destroyed by lysis
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8. KINETIC OF BIOLOGICAL GROWTH IN
PLANT
• The total period from initial to the final stage of
growth is called the grand period of
growth. The total growth is plotted against time
and ‘S’ shaped sigmoid curve (Grand period
curve) is obtained.
i. Lag phase
ii. Log phase
iii. Decelerating phase
iv. Maturation phase
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9. • i. Lag phase
In this phase new cells are formed from pre-existing cells slowly. It is found in
the tip of the stem, root and branches. It is the initial stage of growth. In other words,
growth starts from this period.
• ii. Log phase or exponential growth
Here, the newly formed cell increases in size rapidly by deposition of cell wall
material. Growth rate is maximum and reaches top because of cell division and
physiological processes are quite fast. The volume of protoplasm also increases. It
results in rapid growth and causes elongation of internode in the stem.
• iii. Decelerating phase or Decline phase or slow growth phase
The rate of growth decreases and becomes limited owing to internal and external
or bot the factors because the metabolic process becomes slow.
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10. • iv. maturation phase
In this phase cell wall thickening due
to new particle deposition on the inner
surface of the cell wall takes place.
The overall growth ceases and
becomes constant. The growth rate
becomes zero.
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11. BACTERIAL GROWTH
• Bacteria divide by Binary fIssion.
• Most pathogens grow on artificial culture media.
• Some pathogens have never been grow in
culture.
• Others only grow intracelluarly in tissue culture.
• Generation time is determined by available
nutrients, pH, temp. 11

12. BACTERIAL GROWTH IN LIQUID
MEDIUM
• Microorganisms can be cultivated either in liquid or
solid growth media.
• Liquid media cultivation is done either in small
Universals (up to 20 ml), in Erlenmeyer flasks (up to
1l) and fermenters (from 1l onwards up to excess of
100000 l).
• Methods of liquid cultivation:
1. Batch cultivation
2. Continuous cultivation 12

13. BINARY FISSION
• The normal reproductive method of bacteria is transverse binary
fission in which a single cell divides into two identical cells after
developing a cross wall (transverse)septum.
• It is an asexual reproductive process.
• Thus, bacteria increase their numbers by geometric progression
or exponential growth.
• bacterial population every generation as :
1, 2, 4, 8, etc. Then 2^0, 2^1, 2^2........2^n
(where n = the number of generations). 13

14. • In the center of bacterium, a group of proteins called Fts proteins form
a ring at the cell division plane called as divisome .
• During DNA replication, each strand of the replicating bacterial DNA
attaches to divisome .
• The bacterial cell membrane coordinates the process.
• The two daughter DNA molecules remain attached at divisome, side-
by-side, while new membrane and cell wall is synthesized as a
transverse septum in between the two newly formed chromosomes
• When septum formation is complete the cell splits into two
progenyprogeny cells.
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15. BINARY FISSION FOR BACTERIA
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16. OTHER MECHANISM OF BACTERIAL
GROWTH
• Budding
• Some bacteria reproduce by budding, a process in which a small protuberance
(bud) develops at one end of the cell, enlarges and develops into a new cell
that later separates from the parent cell.e.g.Rhodopseudomonas acidophila
• Fragmentation
• Bacteria that produces extensive filamentous growth reproduce by
fragmentation of the filament into small cells.e.g. Nocardia
• Formation of sporangiospores and Condiospores
• Some species of Streptomyces produce many spores per organism by
developing cross wall at the hyphal tip and each spore give rise to new
organisms.
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17. KINETIC OF BACTERIAL GROWH
GROWTH RATE AND GENERATION TIME
• The time required for a bacterial cell to divide, i.e. a population to
double, during log-phase, is known as the generation time. For a
population, it is often called “Mean Generation Time”.
• Under a given set of growth conditions (medium, temperature,
pH,etc.) each bacterial species has a genetically determined
generation time.
• Typically, generation times range from about 12 minutes to 24 hours.
• Most bacteria of medical interest have generation times of 15 min. to
an hour or so.
• The reciprocal of the Generation Time (1/G) is called the “Growth
Rate Constant” (k, [generations/unit time]).
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18. • The generation time is given by the formula:
G = t/n
where,
G = generation time
t = time interval in hours or minutes
n = number of generations
• Generation time of some bacteria as follows.
1. Escherichia coli - 17min.
2. Bacillus megaterium – 25min
3. Staphylococcus aureus - 27-30 min
4. Mycobacterium tuberculosis - 792-932 min 18

19. KINETIC OF BACTERIAL GROWH CURVE
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20. BACTERIAL GROWH CURVE
• When one measures the growth of a bacterial culture in a closed
system such as a flask or a fermenter and plots the logarithm of cell
number over time then one obtains a characteristic curve, which is
called a bacterial growth curve.
• The growth curve consists of four distinct phases, with a transition
period in between each phase:
1. Lag phase
2. Log (logarithmic or exponential) phase
3. Stationary phase (this is where organisms ‘spend’ most of their time).
4. Decline (death) phase 20

21. BACTERIAL GROWH CURVE
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22. THANK YOU
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