3. Physio- Microorg

PHYSIOLOGY OF MICROORGANISM

NUTRITIONAL REQUIREMENTS      Source of Energy - Phototrophs---light - Chemotrophs– inorganic or organic compounds      Source of Carbon - Autotrophs---CO2 - Litotrophs—inorganic compound except CO2 - Heterotrophs (Organotrophs)  Organic compounds

Energy Source and Carbon Source

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--Photoautotrophs---Light + CO2 ex. Plants, algae, cyanobacteria, purple and green sulfur bacteria --Photoheterotrophs (Photoorganotrophs) --- Light + organic compounds —ex. Green and purple nonsulfur bacteria --Chemoautotrophs– Chemical + CO2 --ex. Nitrifying, hydrogen, iron and sulfur bacteria

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--Chemolitotrophs--- Chemical + inorganic compound except CO2

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-- Chemoheterotrophs– Chemical + organic compound ex. All animals, protozoa, fungi, most bacteria -- Photolithotrophs – Light + inorganic compound except CO2 ex. Plants and algae: producers of food and O2 for chemoheterotrophs

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II. ENVIRONMENTAL REQUIREMENTS A. TEMPERATURE  1. Psychrophilescold loving microbes  2. Mesophiles --moderate-temperature loving organism -- most pathogens and indigenous flora  3. Thermophiles -- heat loving microbes -- ex. Thermophilic cyanobacteria found in hot springs -- Thermodurics: organisms that can survive or endure boiling--- ex. Endospores

GROWTH TEMPERATURES: 1. Minimum Growth temperature - lowest temperature which the species will grow 2. Optimum Growth temperature - temperature which the species grows best 3. Maximum Growth temperature - highest temperature at which growth is possible

B. PH -- acidity or alkalinity of a solution 1. Neutrophiles -- neutral growth medium (pH 7) -- most microorganisms 2. Acidophiles --prefer a pH of 2-5 --microbes that live in the stomach 3. Alkaliphiles (Basophiles) --prefer pH greater 8.5 -- found in intestine

C. OXYGEN REQUIREMENTS -Based on relationship to O2 1. Aerobes---use molecular O2 for life and reproduction a. Obligate aerobes - require an atmosphere that contains O2 similar to room air (20-21% O2), Ex. Mycobacteria b. Microaerophiles - require O2 lower than room air (=5% O2) Ex. Neisseria, Campylobacter

2. Anaerobes - do not require O2 for life and reproduction - vary based on sensitivity to O2 a. Obligate anaerobe - unable to grow in O2 ex. Clostridium b. Facultative anaerobe - capable of surviving in the presence or absence of O2 (0% to 20-21% O2) ex. Enterobacteria, streptococci, staphylococci c. Aerotolerant anaerobe - does not require O2 - grows better in the absence of oxygen but can survive in atmosphere containing O2 ex. Lactobacilli

Based on relationship to CO2 - Capnophiles– grow better in the presence of increased concentrations of CO2 - Anaerobes– Bacteroides, Fusobacterium - Aerobes– Neisseria,Campylobacter, Hemophilus

BACTERIAL GROWTH CURVE - Obtained from growing the organism in pure culture (in vitro) - growth of cells over time 1.       LAG Phase - period of little or no cell division -bacteria absorbs nutrients, synthesize enzymes and prepare for reproduction - period of intense metabolic activity involving DNA and enzyme synthesis

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LOG Phase -exponential growth phase or logarithmic growth phase - cells begin to divide and enter a period of growth or logarithmic increase - cellular reproduction is most active - growth rate is at its greatest - microorganisms sensitive to adverse conditions ex. Penicillin

3. Stationary Phase - period of equilibrium - during this phase that the culture is at its greatest population density - # of cells produced = # of cell deaths 4. Death Phase - Logarithmic decline phase - # of deaths > # of cells formed - toxic waste products increase and nutrient supply decrease

12 10 8

curve Area 2 Area 1

6 4 2 0 1st Qtr

3rd Qtr

III. MICROBIAL GROWTH - An increase in the number of organisms 

Culture Media Requirements: 1. Contain the right nutrients 2. Must be initially sterile 3. Incubated at proper temperature Forms: 1. Liquid (broth)- infusion media 2. Agar– addition of a solidifying agent poured into tubes or Petri

Broth

Types of culture media:

1. Synthetic Media - chemically defined medium - exact chemical composition is known - used for growth of chemoautotrophs and photoautotrophs and microbiological assays. 2. Complex Media - natural medium - contains digested extracts from animals, meats, fish, yeast and plants -used for growth of most heterotrophic

3. Enriched Media - broth or solid medium - containing a rich supply of special nutrients - promote the growth of Fastidious organisms (ex. Complex nutritional requirements) - add nutrients to the basic medium (nutrient agar) ex. Blood Agar --nutrient agar + 5% sheep RBC Chocolate agar --nutrient agar + powdered Hgb - increase numbers of desired microbes to detectable levels

Blood agar

Chocolate agar

4. Selective media - suppress growth of unwanted bacteria - encourage growth of desired microbes Examples: Bismuth sulfite agar--- Salmonella typhi Mac Conkey’s agar– Gram- negative bacteria Thayer-Martin agar --- Neisseria Saboraud dextrose agar--- fungi

5. Differential media - permits the differentiation of organisms that grow in the medium Examples: Mac Conkey’s Agar --- gram negative organisms Lactose fermenters----pink colonies Non-lactose fermenters-- colorless

Mc Conkey agar

Quiz time Please prepare ¼ paper

1. Culture media for Gram (-) organisms Chocolate agar Sabaraud agar Mc Conkey agar 2. Used for Fastidious organisms Selective media enriched media

3. Identify the culture media agar broth 4. Exponential growth Lag phase Log phase stationary phase

5. Require O2 as in room air microaerophile obligate aerobe 6. Unable to grow in O2 facultative anaerobe obligate anaerobe

7. Microbes that live in stomach neutrophiles alkalinophiles acidophiles 8. Light + organic compounds photolithotrophs photoheterotrophs

9. Gram (-) cocci EXCEPT streptococcus neisseria veilonella 10. Gram (+) bacilli EXCEPT Mycobacterium Hemophilus Corynebacterium