Arun- Microbial Growth & Factors Affecting Growth

8/14/2019 Arun- Microbial Growth & Factors Affecting Growth

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&Microbial growth

Factors affectinggrowth

.Arunec ture r in

,icrobiology,h ia ga ra ja r c ol le ge

Madurai


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Growth In Physical term

Increase in size or number of Individual cell

Many factorsDetermine the cell to divide or grow

Physical factorsEnvironmentalconditions,

Temperature, O2,Pressure etc.

Chemical Factors -pH, nutrient etc.


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rowth in Prokaryotes Various biochemical & physical events

From time it derived from parental cell

Until it divides in to two daughter cells

This period of time is called

Bacterial cell cycle


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acterial cell cycle Characterized by Number of event

qGrowth Coordinated synthesis of macromolecules as well as cellularcomponents

qSeptum formationqDivision


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Binary fission


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Binary fission


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rowth Ph ases

Batch culture Continuous culture

Cells grown in batch nutrient Continuous nutrient environment

environment

Microbial populationsMicrobial populations


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rowth cu rve

Cell have various Growth phases

Growth curve


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hases of growth


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Phases of growth


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Lag phase

Require some time to adjust to their newenvironment

Lag Refers lag in cell division

During Lag

1. in size, Produce enzymes to metabolize the nutrients. 2. Synthesize RNA and Protein.

DNA remain constant

Following Inoculation

Increase


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Lag Phase

Is related to

Physiological and genetic state of cell at the time ofinoculation.

Cells Nutritionally starved long Lag phase

If from nutritionally rich short lag phase

engt h of La g phase


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( )Log phase Exponential phase

Phase at which cell division is maintained at a constant andmaximum rate.

e.g., InE.coli Nutrient rich

medium

e.g., InE.coli Less nutrient rich

medium

Take 30 min to divide

Take 60 min to divide


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Log phase

Doubling time Remain constant in log phase

Log Phase said to bebalanced growth

In Log Phase Cellpopulation doubles .So also DNA , RNA &Protein

In Batch Culture:

No nutrient enter

No waste product removedAt one time:

Reach a point rate of growth slows downDue to the factors such as : Over crowding, Nutrietion depletion , pH etcEnd of the Log Phase : Trophophase Primary metabolites produced


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Stationary phase

Number of cellsConstant. Called as Unbalancedgrowth

components & macromolecules Synthesized at different rate

Some cells Divide and others die


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Stationary phase

Cells which are alive produce 2ndary metabolites and wastes

Idiophase


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eath or Decl in e phas e Death of the cell increased


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Continuous culture

In batch culture it can not control the factors (Nutrient supply & waste removal)which

decrease the growth rate.

To Overcome this problem

Continuous culture system can be used.

q Primary purpose of continuous culture

To maintain cell population at constant rate

The devised used Chemo stat & turbidostat


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Factors affecting growth

In addition to Chemical needs also affected by physical nature ofenvironment

Environmental factors Temperature , pH, Osmotic pressure , radiation

Influence the growth of the particular organism


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Temperature

Growth Influenced by Enzymaticreactions TemperaturePlays Imp role

Temperature Max Growth Optimum growth temperature (*)

Above (*) Enzyme get denatured

Below (*) Enzyme get inactivated


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Based on Optimum growth temperature

Psychrophiles

Mesophiles

Thermopiles

Hyper thermopiles


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Psychrophiles

Grow Between 0 to 20c

Found Antarctic, cold soil, Stream, Ocean water, Rivers, Lakemud.

Role Biodegradation in cold water lake, refrigerated foods.

Ribosome Unstable above 20

Psychrophiles protected from cold unsaturated fatty acids

High Temperature Disrupt fatty acid Cell content leak

Lysis


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Thermophiles

Grow Between 40C to 80C.Some grow even in 90C to 100C.

Some G+ / G-Bacilli, Cyanobacteria, Photosynthetic bacteria Thermophiles

- Present in hot springs

- Have normal cell components as is mesophiles

-

With standHigh temperature Presence ofpolar amino acids in interior of cell

Cell membrane componentsMore branched,longer and saturated fatty acid


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Mesophiles

Most Microbes Mesophiles

Temp Range - Between 25 to 40c

Optimum Temp - 37c


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Osmotic pressure

Food with 12% salt No Microbes grow


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Hydrostatic pressure

In every 10meter

One atm. P increase


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Hydrostatic pressure

Barobiology Study the effect of Pressure on Living things.

Barophiles/ Baro tolerant Live in High pressure

Non Barophiles Have gas vacuoles


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Hydrogen ion concentration


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Buffer system used


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Types

Acidophiles

Basophiles

Neutrophiles

dont have peptidoglycon layer

Have Polyhexagonal array of protein forstability

Fungi- Grow in pH 5

Bacteria - Grow in pH 7


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Electromagnetic radiation

Microbes grow - Visible Range


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Electromagnetic radiation

Phototrophs

Use light energy

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Arun- Microbial Growth & Factors Affecting Growth