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