Microbiology Ch. 6

Front 1

microbial growth

Back 1

increase in number of cells, not size

Front 2

Temperature requirements for growth

Back 2

psychrophiles: cold loving
psychrotrophs: food spoilage
mesophiles: moderate temperature loving
thermophiles: heat loving
hyperthermophiles: archea

Front 3

PH requirements for growth

Back 3

-Most bacteria grow between pH 6.5 and 7.5
-Molds and yeasts grow between pH 5 and 6
-Acidophiles grow in acidic environments

Front 4

Osmotic Pressure

Back 4

-Hypertonic environments, increase salt or sugar, cause plasmolysis
-Extreme or obligate halophiles require high osmotic pressure
-Facultative halophiles tolerate high osmotic pressure

Front 5

Carbon sources

Back 5

Autotrophs- CO2 sole or principal biosynthetic carbon source

Heterotrophs- Reduced, preformed, organi molecules from other organisms

Front 6

Energy sources

Back 6

Phototrophs- Light

Chemotrophs- Oxidation of organic or inorganic compounds

Front 7

Electron sources

Back 7

Lithotrophs- Reduced inorganic molecules

Organotrophs- Organic molecules

Front 8

Chemical requirements for growth

Back 8

carbon, nitrogen, sulfur, phosphorus, trace elements, organic growth factors, oxygen

Front 9

Carbon

Back 9

structural organic molecules, energy source
-chemotrophs use organic carbon sources
-autotrophs use CO2

Front 10

Nitrogen

Back 10

In amino acids, proteins
-Most bacteria decompose proteins
-Some bacteris use NH4+ or NO3-
-A few bacteria use N2 in nitrogen fixation

Front 11

Sulfur

Back 11

In amino acids, thiamine, biotin
-Most bacteria decompose proteins
-Some bacteria use SO4^2 or H2S

Front 12

Phosphorus

Back 12

In DNA, RNA, ATP, and membranes
- PO4^3- is a source of phosphorus

Front 13

Trace elements

Back 13

inorganic elements required in small amounts
-usually as enzyme cofactors

Front 14

Organic growth factors

Back 14

organic compounds obtained from the environment
-vitamins, amino acids, purines, pyrimidines

Front 15

Oxygen

Back 15

obligate aerobes; faultative anaerobes; obligate anaerobes; aerotolerant anaerobes; microaerophiles

Front 16

Toxic forms of oxygen

Back 16

singlet oxygen, superoxide free radicals, peroxide anion, hydroxyl radical

Front 17

culture medium

Back 17

nutrients prepared for microbial growth

Front 18

sterile

Back 18

no living microbes

Front 19

inoculum

Back 19

introduction of microbes into medium

Front 20

culture

Back 20

microbes growing in/on culture medium

Front 21

Agar

Back 21

complex polysaccharide
-Used as solidifying agent for culture media in petri plates, slants, and deeps
-generally not metabolized by microbes
-liquifies at 100 degrees C
-solidifies ~ 40 degrees C

Front 22

Chemically defined media

Back 22

exact chemical composition is known

Front 23

complex media

Back 23

extracts and digests of yeasts, meat, or plants.

eg Nutrient broth; nutrient agar

Front 24

Anaerobic Culture Methods

Back 24

-Reducing media: contain chemicals (thioglycollate or oxyrase) that combine O2--heated to drive off O2
-Anaerobic jar
-Anaerobic chamber
-Capnophiles require CO2, Candle jar, CO2-packet

Front 25

Selective media

Back 25

supress unwanted microbes and encouage desired microbes

Front 26

differential media

Back 26

make it easy to distinguish colonies of different microbes

Front 27

enrichment media

Back 27

encourages growth of desired microbe

Front 28

pure culture

Back 28

contains only one species or strain

Front 29

colony

Back 29

a population of cells arising from a single cell or spore or from a group of attached cells
-often called a colony-forming unit (CFU)

Front 30

Preserving bacteria cultures

Back 30

deep freezing: -50 to -95 degrees C

lyophilization (freeze drying): Frozen (-54 to -72C) and dehydrated in a vacuum

Front 31

Reproduction in prokaryotes

Back 31

binary fission, budding, conidiospores (actinomycetes), fragmentation of filaments

Front 32

Direct measurements of microbial growth

Back 32

-plate counts: perform serial dilutions of a sample. Filtration.
-multiple tube MPN test: count positive tubes and compare to statistical MPN table
-Direct Microscopic Count

Front 33

Estimating Bacterial numbers by Indirect Methods

Back 33

Turbidity; metabolic activity; dry weight