Bacterial Growth Curve microbiology | Log phase lag phase stationary phase in microbial growth bacterial growth curve microbiology In this video, I will be discussing what the bacterial growth curve reflects, different phases & their significance. Bacterial growth curve and microbial growth kinetics - This microbiology lecture is going to teach you about the bacterial growth curve and the microbial growth kinetics. The microbial growth curve consists of 4 phases. Lag phase of the growth curve, Log phase of the bacterial growth curve which is also known as the exponential growth phase and the stationary phase of bacterial growth curve where the bacterial growth is about to stop. The last phase of microbial growth curve is the death phase where the cell death is complete and the bacterial population starts declining. Stay tuned to know more about the bacterial growth curve microbiology. Thank you for watching the video lecture on microbial growth curve microbiology. As the channel name suggests, our channel will be a perfect lounge for the malayali medicos..we wil be covering videos which will be like lecture classes related to the subjects biochemistry and microbiology in which we are specialised.. It will be a better learning experience for the students especially for those who are not able to understand and follow the normal classes in college..we assure the students that you will get a basic idea regarding the topic and extra reading can be done from the reference textbooks... If you like my video #like #comment #subscribe my channel don't forget to subscribe my channel Qualification Maneesha M Joseph MSc MLT (Microbiology) Assistant Professor Baby memorial college of allied Health science Kozhikode Our Partner Channel Health & Voyage channel link - https://youtu.be/nzKqRVjlwc0 #Mallu #Microbiology #Biochemistry #MalluMedicosLounge #HealthAndVoyage Bacterial Growth Curve

1. BACTERIAL
GROWTH
CURVE
• By
• MANEESHA M JOSEPH
• ASSISITANT PROFESSOR
• BABY MEMORIAL COLLEGE
• KOZHIKODE
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2. The bacterial
growth curve
shows the
following four
distinct
phases:
1. Lag phase:
• After a liquid culture broth is inoculated, the
multiplication of bacteria does not start immediately. It
takes some time tomultiply.
• The time between inoculation and beginning of
multiplication is known as lag phase.
• In this phase, the inoculated bacteria become
acclimatized tothe environment, switch on various
enzymes, and adjust to the environmental temperature
and atmospheric conditions.
• During this phase, there is an increase in size of
bacteria but no appreciable increase in number of
bacterial cells. The cells are activemetabolically.
• The duration of the lag phase varies with the bacterial
species, nature of culture medium, incubation
temperature, etc.
• It may vary from 1 hour to several days.
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3. 2. Log
phase:
• This phase is characterized by rapid exponential cell
growth (i.e., 1 to 2 to 4 to 8 and so on).
• The bacterial population doubles during every
generation. They multiply attheir maximum rate.
• The bacterial cells are small and uniformly stained.
• The microbes are sensitive to adverse conditions,
such as antibiotics and other antimicrobial agents.
• Growth rate is the greatest during the log phase.
• The log phase is always brief, unless the rapidly
dividing culture is maintained by constant addition of
nutrients and frequent removal of waste products.
• When plotted on logarithmic graph paper, the log
phase appears as a steeply sloped straight line.
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4. 3.
Stationary
phase:
• After log phase, the bacterial growth almost
stops completely due to lack of essential
nutrients, lack of water oxygen, change in pH
of the medium, etc. and accumulation of
their own toxic metabolic wastes.
• It is during this phase that the culture is at its
greatest population density.
• However, Death rate of bacteria exceeds the
rate of replication of bacteria.
• Endospores start forming during this stage.
• Bacteria become Gram variable and show
irregular staining.
• Many bacteria start producing exotoxins.
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5. 4. Decline
phase:
• During this phase, the bacterial population declines due
to death of cells.
• The decline phase starts due to
(a)accumulation of toxic products and autolytic enzymes
and
(b)exhaustion of nutrients.
• Involution forms are common in this stage. Some cells
assume various shapes, becoming long, filamentous
rods or branching or globular forms that are difficult to
identify.
• Some develop without a cell wall and are referred to as
protoplasts, spheroplasts, or L-phase variants (L-forms).
• When these involuted forms are inoculated into a fresh
nutrient medium, they usually revert to the original
shape of the healthy bacteria.
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6. MANEESHA M JOSEPH 6