BACTERIAL GROWTH CURVE -
introductions - bacterial growth curve show the bacterial life cycle such as adjustment in new environment, growth and nutrition, death etc. in bacterial growth curve we are explain the different phase of bacterial life bacterial growth curve seen in under the culture medium. bacterial growth curve consist of four phase. they is lag phase, long phase(exponential phase), stationary phase , death phase.
what is bacteria - bacteria is a large group unicellular organism that is cause disease in human beings such as skin infection, tuberculosis , waterborne disease, etc.
1. lag phase- during this phase bacteria adjust themselves in new environment. in lag phase bacterial metabolic activity in which bacteria prepare for reproduction and synthesizing DNA ,enzyme for needed cell division . during lag phase bacteria increase size but not increase number of cell. the length of lag phase depend on bacteria quality
- this phase bacteria adjust in new environment
- bacteria increase metabolic activity
- bacteria prepare for reproduction
- synthesizing DNA
- in this phase bacterial size increase but not increase number of cell.
2. log phase(exponential) -
this phase is characterized by cell doubling .during this phase bacteria multiply at maximum rate and their number increase exponentially. this phase where generation time can be calculated. in this phase bacteria cell increase very fastly .bacteria growing in a constant medium of culture therefor duration of this phase is limited because of exhaustion of nutrition accumulation of toxic metabolic end product decrease in O2 tension and increase in cell density .
- in this phase cell doubling
- multiply bacteria cell
- in this phase generation time is calculate
- bacteria going consent medium
3. stationary phase -
during this phase the growth rate slows down as a result of nutrition. The stationary phase is often due to a growth-limiting factor such as the depletion of an essential nutrient, or the formation of an inhibitory product such as an organic acid. Stationary phase growth rate and death rate are equal. The number of new cells created is limited by the growth factor and as a result the rate of cell growth match the rate of cell death.in bacteria survive
- growth rate and death rate are equal
- growth depend on limited nutrition
- cell growth match the rate of death cell
- growth rate is slow
- bacteria death due to lack of nutrition
- death of bacteria due to increase and decrease temperature
- after dies bacteria population culture become sterile
factor affecting bacterial growth
some factor affect the growth and nutrition of bacteria they are following
- TEMPERATURE
- NUTRITION
- MOISTER
- BLOOD AND BODY FLUID
- LIGHT
- OSMOSIS
- PH
1. TEMPERATURE -
Bacteria requires a certain temperature for it,s growth called optimum temperature .Bacteria which attacks human body live based at temperature that is for most pathogenic bacteria .The optimum temperature is 37 degree c most bacteria are killed at 56C degree in 30 minutes .Bacteria have a minimum optimum and maximum temperature for growth and can be divide into three groups based on their optimum growth temperature .
A.minimum
B.maximum
C.Optimum
1. Minimum growth temperature-
The lowest temperature at which organisms growth is the minimum growth temperature.
2. Maximum growth temperature-
The highest temperature at which growth is maximum growth temperature .
3. Optimum growth temperature-
The temperature at which rapid rate of multiplication occurs .
Classification of bacteria according to growth temperature
1. Psychrophiles
Psychro - cold
Philes - loving
Psycrophiles are cold loving bacteria their optimum growth temperature range is - 20 ℃ to 10 ℃ . they are uselly found cold place .
Example - Novalis ,
methanogenium , oscillatoria .
2. Mesophiles
Meso - medium temprature
Philes - loving
Mesophiles are bacteria growth temperature 20 ℃ to 45 ℃ ,most bacteria are mesophiles like comma .
Example - streptococcus , coli.
3. Psychrotrops
Cold tollrens bateria
Have optimum and maximum growth tempreture above 15 ℃ to 20 ℃ .
Example - they bacteria mostly found food material ( fungi , baccillus , streptococcus ).
4. Thermophiles
Thermo - heat
Philes - loving
Thermophiles are heat loving bacteria . thermo word derived from Greek word " thermolita " meaning heat and philia meaning love . head loving microorganisms mostly growth in 45 ℃ to 80 ℃ temperature .
Example - thermos , geogemma .
5. Hyperthermophiles
They bacteria are heat loving bacteria they are mostly found in hot places. There optimum temperature range is 80 ℃ to above 100 ℃ . they are first time discovered in ( 1965 ).
Example - methanococcus , sulfolovus.
2 NUTRITION -
Bacteria obtained their nutrition from organic and inorganic materials from growth multiplication most bacteria of medically is available as source of food every organism must find in its environment all of the substance required for energy generation and cellular biosynthesis the chemical and elements of this environment they are utilize for bacterial growth some measure elements of bacteria growth.
3 MOISTER
Moisture like all living things bacteria are sensitive to their environment water is necessary for the growth of bacteria because they can not absorbed food material without water they cannot survive in the absence of water.
4. BLOOD AND BODY FLUID
Bacteria enter into the human blood through the any injury of the body respiration food materials and mixed in blood streams so nutrition such as vitamin. Protein. Iron. fatty acids. fat. Potassium. Magnesium. Sulphur are present in the blood bacteria are take the energy through the blood because nutrition is present in blood they are provide energy of bacterial growth bacteria fastly grow in human blood and cause disease in human body.
Due to any injury
↓
Bacteria enter into the human blood stream
↓
Measure elements of nutrition are present in blood
↓
Bacterial growth
↓
Cause disease.
5. LIGHT
A bacteria usually grow in darkness.
6. OSMOSIS
Osmosis it the diffusion of water across a membrane from a area of water higher concentration to lower water concentration ,this process help the bacteria growth
7. PH
-most of the pathogenic bacteria grow best in a neutral (ph. 7.2 to 7.6) medium
-most of the pathogenic bacteria grow best in a neutral (ph. 7.2 to 7.6) medium
- neutrophiles - grow best at ph range 5 to 8
- acidophiles - grow best At ph below 5.5
- alkaphiles - grow best at ph above 8.5
some harmful bacteria -
gram positive
- mybacterium tuberculosis - this bacteria are responsible for causing tuberculosis
- bacillus - it is responsible for food poisoning
- corynebacterium - it is gram positive bacteria its caused diphtheria in human beings
- mycoplasm - it is responsible for causing pneumonia
- nocardia - it is responsible for respiratory disease
- borrelia - it is cause arthopod borne disease
- bortadella - its is caused pertusis
- entrobacter- it is responsible for urinary-tract infection
- helicobacter - it caused peptic ulcer
- hemophilus - its caused meningitis
0 comments:
Note: only a member of this blog may post a comment.