NUTRITION AND GROWTH
• EVERY LIVING ORGANISM MUST ACQUIRE
2 THINGS FROM ITS ENVIRONMENT IF IT IS
TO GROW AND REPRODUCE:
• STRUCTURAL UNITS
• ENERGY SOURCE
• GROUPING ORGANISMS BASED ON
NUTRITIONAL REQUIREMENTS:
•
•
•
•
PHOTOHETEROTROPHS
PHOTOAUTOTROPHS
CHEMOHETEROTROPHS
CHEMOAUTOTROPHS
• EXAMPLES OF ORGANISMS FOUND IN EACH
GROUP
• HOW DO ORGANISMS ACQUIRE THEIR
NUTRITIONAL NEEDS?
• IT IS PROVIDED TO THEM IN A MEDIUM
• MEDIA - LAB OR ENVIRONMENT
• ALL MEDIA MUST HAVE THE FOLLOWING CHEMICAL
ELEMENTS FOR GROWTH
- CARBON (C)
- NITROGEN (N)
- WATER(H2O)
- MINERALS(S,P,Ca,Mg,Na, etc.)
• CARBON SOURCES: 1)CARBON DIOXIDE;
2)CARBOHYDRATES
• CARBOHYDRATES ARE SELECTED
BECAUSE:
• WATER SOLUBLE
• READILY ACCESSIBLE IN LAB AND NATURE
• USUALLY NON TOXIC IN DILUTE
CONCENTRATION
• EASILY OXIDIZED AND REDUCED, LITTLE
MODIFICATION NEEDED
• SOME ORGANISMS CAN NOT USE
CARBOHYDRATES AS A CARBON SOURCE.
• THEY WILL USE ALCOHOLS, AMINO ACIDS,
FATS, ETC.
• NITROGEN SOURCES: 1) INORGANIC; 2)
ORGANIC
• INORGANIC SOURCE : NITROGEN GAS(N2)
OR NH4CL/(NH4)2SO4
- NITROGEN FIXATION
- SYMBIOTIC RELATIONSHIPS.
ORGANIC NITROGEN SOURCE
• PROTEIN
• BUILDING BLOCKS OF PROTEINS ARE
AMINO ACIDS
• PRIMARY, SECONDARY,TERTIARY,AND
QUATENARY SRUCTURE OF PROTEINS
• MINERALS:
• MICRONUTRIENTS: ZN, CU, CO, MN, MO
• MACRONUTRIENTS: P, Mg, Ca, S, Na
• WATER - BIOLOGICAL SOLVENT THAT
COMPOSES 80-85% OF THE WEIGHT OF
CELLS.
• SUBSTANCES WHICH MAY BE ADDED TO
MEDIA BUT ARE NOT ALWAYS REQUIRED.
- GROWTH FACTORS
- BUFFERS
- SOLIDIFYING AGENTS
• STERILIZATION OF MEDIA
- AUTOCLAVING
- FILTRATION
a) NEGATIVE
b) POSITIVE
CLASSIFICATION OF MEDIA
• SYNTHETIC OR CHEMICALLY DEFINED
MEDIA
• A CHEMICAL FORMULA CAN BE WRITTEN
FOR EVERY INGREDIENT
• COMPLEX MEDIA
• A CHEMICAL FORMULA CANNOT BE
WRITTEN FOR EVERY INGREDIENT
OXYGEN GAS REQUIREMENTS OF
MICROORGANISMS
•
•
•
•
•
OBLIGATE AEROBES
FACULTATIVES
AEROTOLERANTS
MICROAEROPHILICS
OBLIGATE ANAEROBES
GROWTH
• DEFINITION: INCREASE IN MICROBIAL MASS OR
INCREASE IN THE NUMBER OF CELLS
• GENERATION TIME: THE TIME IT TAKES AN
ORGANISM TO REPRODUCE
– BINARY FISSION
– SHORTER FOR PROCARYOTES THAN
EUCARYOTES
– ENVIRONMENT EFFECTS GENERATION TIME
WE CAN DEMONSTRATE TYPICAL
BACTERIAL GROWTH BY PREPARING A
POPULATION GROWTH CURVE.
• THE BACTERIAL GROWTH CURVE
– LAG PHASE
– LOG OR EXPONENTIAL PHASE
– STATIONARY PHASE
– DEATH OR DECLINE PHASE