Nutrition, Growth, and Control of Microbes

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Diane Mauldin, Biology 260, Exam 3

nutritional requirements for growth

A. A source of energy.
B. A source of carbon (CO2 or organic molecules)
C. A source of nitrogen via nitrate salts for amino acids, purines, and pyrimidines.
D. A source of sulfur for some amino acids and some coenzymes.
E. Vitamins for coenzymes
F. A source of phosphorous (phosphates) for ATP and nucleic acids.
G. Minerals:
1. Na+, Ca++, etc.
2. Include trace element metals for cofactors (zinc, Cu, etc).
H. Water (keeps molecules in solution, hydrolysis)

Nutritional Types

1. Autotroph
2. heterotroph
3. phototroph
4. chemotroph

autotroph

acquires its carbon from carbon dioxide

heterotroph

acquires its carbon from an organic source

phototroph

acquires its energy from light

chemotroph

acquires its energy from organic or inorganic molecules

photoautotroph

photosynthetic organisms i.e., plants, algae, some bacteria and protozoa

photoheterotroph

photosynthetic bacteria that use organic acids as a carbon source

chemoheterotroph

animals, most protozoa, most bacteria, and fungi

chemoautotroph

possibly the most numerous organisms on the planet, archaea

temperature range

where the microbe can grow

temperature optimum

where the microbe grows best (near the top of a microbes range)

psychrophile

0 to 20, refrigerator spoilage and plant diseases

mesophile

10 to 47, human disease causing microbes

psychrotolerant

a mesophile that can grow at 0, disease and spoilage

thermophile

45 to 80, few human disease, compost piles

hyperthermophile

over 80, includes extremophiles (also under 0)

extreme temperature affects:

bacterial enzymes and structural proteins (archaea have the proteins that can survive these extremes)

generate ATP

1) fermentation
2) anaerobic respiration
3) aerobic respiration
4) oxygenic photosynthesis
5) anoxygenic photosynthesis
6) archaea photosynthesis

does not generate ATP

chemosynthesis

does sugar synthesis

1) oxygenic photosynthesis
2)anoxygenic photosynthesis
3) chemosynthesis

ATP --> synthesis --> growth & reproduction

-protein
-DNA/RNA (nucleoside triphosphate)
-lipids
-carbohydrates

bordatella pertussis: reproduction

binary fission

bordatella pertussis: metabolism

chemoheterotroph

bordatella pertussis: carbohydrate source

organic

bordatella pertussis: energy source

organic

psychrophile optimum

15

mesophile optimum

37

psychotolerant optimum

20 to 40, but can grow at as low as 0

requirements for growth & reproduction

1) adequate nutrition
2) optimum temperature
3) optimum leveles of O2 (or no O2) media
4) optimum pH
5) optimum osmolarity

O2 requirements reflect metabolic pathways and enzymes such as:

1) fermentation vs cellular respiration
2) ability to produce catalase and superoxide dismutase

obligate aerobes

O2 must be present

microaerobes

can tolerate a small amount of O2

facultative anaerobes

can live with or without O2

pasteur point

oxygen level at which an organism switches from aerobic to anaerobic metabolism

obligate anaerobes

cannot live in the presence of O2 - no superoxide dismutase or catalase

neutrophile

optimum pH 7

acidophile

optimum pH 3

alkalinophile

optimum pH 12

osmotic effects: high solute concentrations in a cells environment result in:

cellular dehydration and plasmolysis with protein precipitation

osmotic effects: low solute concentrations in a cells environment result in:

water entering the cell such that cells may lyse

osmophiles

require an environment with a high concentration of sugar

halophiles

require an environment with a high salt concentration to stabilize their membranes

osmophiles and halophiles:

1) don't dehydrate because they concentrate compatible solutes that don't interfere with their metabolis, e.g. K+ and amino acids
2) some have water binding proteins

media types

1) synthetic
2) nonsynthetic
3) enriched
4) selective
5) differential
6) liquid
7) solid

synthetic

chemically defined

nonsynthetic (complex)

infusions and extracts ("rich"), e.g. nutrient broth and nutrient agar we use in class

enriched

additves are included to promote growth of fastidious bacteria, e.g. TSA and blood agar

selective

prevents the growth of one type of bacteria without inhibiting the growth of another type, e.g. EMB, Columbia CNA, SM 110, and mannitol salt agars

SM 110

only one that is only selective

EMB and Hektoen

selective against G+

Columbia CNA

selective against G-

Chromagar

only one that is only differential

differential

the way an organism grows on or its effect on a media helps tell the bacteria apart, e.g. EMB, blood and ChromAgar, MsA, Columbia CNA

liquid

good for propagating large numbers of organisms as well as for testing

solid

shows surface growth patters; convenient for "pure culturing" organisms

generation time

the time it takes to double the number of viable cells

growth of unicellular organisms

= more individuals via mitosis or binary fission
= a larger population of cells
= reproduction

population growth rate

dependent on the population's generation time

lag phase

1) cell growth, increase in cell mass
2) varies depending upon the condition and nature of the initial cells
a)dormant vs dividing cells
b)slow dividers vs fast dividers
c)the transition to the log phase is sensitive to temperature, osmotic pressure, etc.

log phase: cells are dividing at a rapid and constant rate (exponential or logarithmic)

1)the rate related to environment conditions (i.e. optimum vs sob-optimum
2)proportional to the rate of energy metabolism
3) microbes are particularly susceptible to antibiotics and other chemical agents at this time

log phase: duration

1) related to cell density, "biological space", or M concentration
2) the accumulation of toxic products and the exhaustion of nutrients terminates this phase
3) related to genetics of the organism, i.e. aerobic organisms produce fewer toxic wastes

stationary phase

1) there is a balance between divisions and death; no increase in the number of viable cells
2) cells begin to produce defensive proteins and go into survival mode
3) the length of this phase varies with the kinds of wastes and the temperature
4) the cells most sensitive to the changing conditions die first

death phase

1) bacteria are dying exponentially
2) the death curve doesn't drop to zero due to the presence of resistant individuals and/or endospores
3) organisms are no prepared for growth; there is a long lag phase if microbes are transferred to a fresh medium

phases of bacterial population growth

1) lag phase
2) log phase
3)stationary phase
4) death phase

isotonic

equal concentrations of a substance found inside of cell and outside of cell

Most convenient technique for measuring bacterial growth

turbidity, but also includes dead cells, even "clear" cultures may have millions of cells

most sensitive technique for measuring bacterial growth

plate count

viable plate count, serial dilution

continuously dilute bacterial through different vials until the petri plate has a reasonable amount of colonies to count.
Multiply number of colonies counted by dilution to give total number of bacteria in substance.

bacterial population size equation

population size = a x 2n
a = the number of cells with which you start
n = number of generations

inhibit bacteria

=static
- bacteriastatic

kill

-cide
1)bactericide
2)viricide
3)fungicide
4)germicide
5)sporicide (destroys bacterial or fungal spores)

dry heat

sterilizes -----> incerate, dry oven

moist heat

-boiling
-autoclave (pressure cook)
-pasteurization

boiling

sterilizes if spores are no present

autoclave (pressure cooker)

results in temperatures above boiling, good penetration, the most practical and dependable

pasteurization

1) does not sterilize
2) used to eliminate pathogens from food products (usually beverages)
3) controlled heat below boiling, e.g. 72C for 15 seconds
4) media that are concentrated or contain fats and sweeteners (skim milk vs cream) require higher temperatures

pasteurization created because of

TB found in animals which could spread to humans. Also rids of E.Coli and Listeriosis.

does pasteurization sterilize?

No

Does tyndallization sterilize?

Yes

to reduce the number of microbes

-disinfect
-antiseptic

disinfect

reduce the number of pathogens off of inanimate surfaces

antiseptic

reduce or inhibit microbes on living tissue

to eliminate microbes

-sterilization
-decontaminate

sterilization

remove or kill all microbes (incapable of reproducing)

decontaminate

you sterilize plus remove microbial toxins

thermal death point (TDP)

lowest temperature at which microbes are killed in 10 minutes

thermal death time (TDT)

shortest time it takes to kill all microbes at a given temperature

dilution tests

1)bacteria are added to tubes with different dilutions of a chemical agent and then incubated
2) this method is used to identify agents that prevent growth at the greatest dilution.
3)MIC
4)MBC

minimal inhibitory concentrations (MIC)

the tube with the lowest amount of agent that is without visible growth (turbidity method)

minimum bactericidal concentration (MBC)

the tube with lowest amount of agent that is without any growth.
-start with tube after MIC, spread out on petri dish until no bacteria is left

Microbe most likely resistant to that antibiotic has an MIC of

over 1, want lowest MIC antibiotic you can find.

three prokarya molecules recognized by toll-like receptors

1) peptidoglycan
2) lipopolysaccharide
3) flagellin
4) porin protein

production of beta-lactamase makes bacteria resistant to what family of antibiotics?

penicillin

identify the tenericute that attacks mucous membranes and the synovial membranes of the joints.

mycoplasma

explain the difference between lateral gene transfer and vertical gene transfer.

lateral gene transfer transfers genes to a neighboring cell.
vertical gene transfer transfers genes to daughter cells

When preparing a smear for this stain, you expect to heat-fix it.

positive stain

Enzymes speed chemical reactions by

decreasing the activation energy required for a reaction

In the context of genetic engineering, the term vector refers to

the DNA into which a gene is spliced

CO2, H2, and CH4 can be generated by this metabolic process.

fermentation

CO2 is always generated by this metabolic process.

aerobic cellular respiration and anaerobic cellular respiration

Paul Ehrlich

-Made the first systematic attempt to find a selective agent to treat disease.
-Found methylene blue, injected into a rabbits ear, stained only neuron endings. It was selective, he want to find more like it for humans.

Ehrlich: dyes & arsenic compounds used in dyes

-trypan red 500 sometimes in mice
-atoxyl 591 (arsenic red)
-salvarsan 606

trypan red 500

killed trypanosomnes sometimes in mice

atoxyl 591

(arsenic red) killed trypanosomes, made mice dance

salvarsan 606

(salvation + arsenic, derived from atoxyl)
-killed trypanosomnes in mice and horses, no side effects
-read that spirochetes were cousins to trypanosomes (but they are not)
-cured rabbits of syphilis (but only humans can get it)
-cured thousands of people of syphilis but also killed occasional person
-first "blockbuster" drug, most widely prescribed in world at a time
-may have caused initial spread of HIV because of sharing needles

sensitivity disks (filter paper method)

-look for clear area around paper disks soaked in a given agent - where bacterial growth has been inhibited (inhibition zone)
1)the media used in determining sensitivity should be comparable to tissue fluids of th body
2) staph a is the usual test organism
3) can't tell if the organisms are dead or inhibited
4)various agents diffuse through agar at different rates

death curves

counts of viable bacteria made at intervals

gerhard domagk

1) produced the first sulfa drug
2) the dye prtonsil converts to sulfanilamide once introduced intro the patient
3) sulfa drugs were the first effective broad specturm selective agents

targets of antibiotics

-cell well - bacitracin
cell memberane - polymyxins
-dna/rna - nadaladaxic acid, ciproflaxin?
-ribosome -erythromycin, tetracycline
metabolic products

characteristics of anitbiotics

1) usually selective
2) produced y bacteria and molds
3) target bacteria
4) broad spectrum
5) low toxicity index
6) high therapeutic index

antibiotics at low concentrations (most common in nature

-communication molecules, inducer
1)stimulate biofilm production
2) gene expression
-may be metabolic intermediates and nutrient molecules

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