Ch 6: Bacterial Growth

isolation streaking

separation of colonies into pure cultures

spread plate

tenfold dilutions of the original culture are spread on agar plates

each colony is a viable organism

synthetic medium

medium that only contains known components

minimal medium

synthetic medium where the components are limited to essential nutrients for growth

complex medium

nutrient rich but less defined medium

enriched medium

complex medium and extra nutrients

can be used to grow fastidious organisms

blood, meat, soybean, milk, peptone

examples of complex media

selective media

inhibitor present to only encourage growth of specific organism

differential media

multiple types grow but look visually different

selective (gram negative) and differential (lactose)

fermenting = red, nonfermenting = white

what type of media is MacConkey?

salmonella and shigella

which gram negative bacteria species do NOT ferment lactose?

enriched differential and not selective

what type of media is blood agar?

staphylococcus aureus

what type of organism exhibits beta hemolysis?

binary fission

how does bacteria grow and divide?

false

true or false: bacterial reproduction is always symmetrical

doubling time

in an environment with few bacteria but plenty of resources, bacteria will divide at a constant interval called

No times 2 power n

No is number of organisms at time 0, n is generations

equation for bacterial growth

grow and die

bacteria blank and blank exponentially

batch culture

culture bacteria in flasks or test tubes containing liquid medium

true

true or false: bacteria grow slower in batch culture because there is a limited amount of nutrients and accumulation of waste

lag phase

bacteria are preparing their cell machinery for growth

log phase

when bacteria is most actively growing

stationary phase

cells stop growing and shut down their growth machinery while turning on stress responses to retain viability

death phase

cells begin to die at an exponential rate

log phase

which phase of bacterial growth are bacteria most susceptible to antibiotics that target cell wall synthesis, protein synthesis, or DNA replication?

chemostat

ensures exponential growth by constantly adding and removing equal amounts of culture medium

growth factor

an essential organic compound that a specific microorganism must have to survive and grow but cannot synthesize

rickettsia

example of fastidious organism?

auxotroph

mutant organisms that have lost the ability to synthesize a particular growth factor required for their growth

fastidious organism

organisms that have complex nutritional requirements and require enriched media (need specific growth factor)

not mutant

autotroph

organisms that make their own carbon compounds starting with CO2

heterotroph

organisms that obtain carbon compounds from other organisms

phototroph

organisms that use light as an energy source

chemotroph

organisms that use chemical compounds as an energy source

lithotroph

chemotrophs that use inorganic compounds as energy

organotroph

chemotrophs that use organic chemical compounds

extremophile

bacteria, archaea, and some eukaryotic microbes that can grow in extreme environments

thermophile

organism that has membranes and proteins adapted to high temperatures

protein folding is very tight

membrane has ether bond (less reactive)

Thermus aquaticus

what hyperthermophile has TAQ polymerase?

psychrophile

organism that can survive in low temps

has proteins that are more flexible

mesophile

organism that grows in typical conditions (20-40 C)

barophile

organisms that have adapted to grow at oppressively high pressures

typically also psychrophiles

halophile

species of archaea that require high concentrations of salt to survive

neutrophile

bacteria that grow between pH 5-8

alkaliphile

organism that grow best at pH 9-11

neutrophile

what type of organism is Helicobacter pylori?

highly motile and breaks down urea into basic ammonia

how does Helicobacter pylori survive in the acidic environment of the stomach?

strict aerobe

only survives in environment with oxygen

can detoxify reactive oxygen species

strict anaerobe

only survives in environment without oxygen

cannot detoxify reactive oxygen species

microaerophile

aerobic

survives in environments with lower oxygen concentration but still req oxygen

aerotolerant anaerobe

prefer anaerobic conditions but can survive oxygen environment

facultative anaerobe

both aerobic and anaerobic

better to have oxygen tho due to efficiency

top

where does obligate aerobe grow in tube?

bottom

where does obligate anaerobe grow in tube?

spread but more on top

where does facultative aerobe grow in tube?

between high and low oxygen

where does microaerophile grow in tube?

evenly distributed

where does aerotolerant grow in tube?

pseudomonas fluorescens

aerobic organism

clostridium spp endospore

anaerobic organism

e coli

facultative organism

helicobacter pylori

microaerophilic organism

superoxide radical, hydrogen peroxide, hydroxyl radical

types of reactive oxygen species?

hydroxyl radical

what is the most dangerous ROS?

SOD

what enzyme detoxifies superoxide radical?

catalase and peroxidase

what enzymes detoxifies hydrogen peroxide?

anaerobe jar

container where O2 is removed and CO2 is generated

anaerobe chamber

container with glove ports that remove the atmosphere via vacuum and replace it with a precise mixture of N2 and CO2 gases

facultative anaerobe, strict anaerobe, aerotolerant

what types of organisms can grow in the anaerobic jar?

biofilm

mass of bacteria that stick to and multiply on a solid surface

typically multiple types of bacteria

quorum sensing

only for prokaryotes

coordinate group behavior (gene expression)

bacteria release autoinducers, as autoinducer concentration increases, the signal binds to receptors turning on specific genes and coordinated group activity occurs

explain process of quorum sensing

spore coat has dipicolinic acid and calcium which makes it very dry, reducing reactivity to the environment

how do endospores stay so resilient?