ch 6

Question 1

Pure culture (agar) –Koch and Hesse

Answer 1

A single, genetically homogeneous strain of a single species.

can be grown in liquid or solid media
used to examine growth rates & microbial biochemistry
useful for separating mixtures of different organisms

Question 2

Isolation streaking

Answer 2

using an inoculation loop to dilute cells

Question 3

serial dilutions with spread plate for counting viable colonies

Answer 3

p

Question 4

Synthetic (minimal) media vs. Complex (rich) media vs. enriched media

Answer 4

synthetic-Water, salts, carbon, nitrogen, and energy sources added in precise amounts

complex-Nutrient-rich but poorly defined
Yeast/beef extract, peptides, vitamins whose exact concentration and composition is not known

enriched-For particularly fastidious organisms, blood or blood components added to a basic complex medium

Question 5

Selective vs. differential media (can be both at times)

Answer 5

Selective media favor the growth of one
organism over another.

Differential media expose biochemical differences between 2 species that grow equally well.

Question 6

Bacteria divide by binary fission

Answer 6

Binary fission is one parent cell splitting into two equal daughter cells.

Binary fission can be symmetrical or asymmetrical.

Caulobacter, Hyphomicrobium reproduce by budding

Eukaryotic microbes divide via mitosis

Question 7

Know the 4 phases of microbial growth

Answer 7

1. lag phase
   
   2. log or exponential phase
   3. stationary phase
   4. death phase

Question 8

Know that gram staining should be done in the log phase of growth to yield proper results

Answer 8

t

Question 9

Know terminology and environmental requirements:

Psycrhophiles (cold temp.)

Answer 9

grow at temperatures as low as 0° C but their optimum growth temperature is around 14° C.

Question 10

Know terminology and environmental requirements:

Mesophiles (intermediate including body temp.)

Answer 10

have optimal growth between 20–40°C, with a minimum of 15°C and a maximum of 45°C.

Question 11

Know terminology and environmental requirements:

Thermophiles (hot temp.) and Hyperthermophiles or Extreme thermophile

Answer 11

Thermophiles have adapted to growth at high temperatures, typically at 55°C and higher.

Hyperthermophiles can grow at temperatures as high as 121°

Extremophiles are bacteria, archaea, and some eukaryotes that can grow in extreme environments.

Question 12

Barophiles –high pressure

Answer 12

Organisms that have adapted to grow at high pressures are called barophiles

Question 13

Halophiles—high salt

Answer 13

Species that have evolved to require high salt (NaCl) concentrations are known as halophiles.

Question 14

Acidiophiles (acid, low pH)

Answer 14

are bacteria and archaea that live in acidic environments. They are often chemoheterotrophs that oxidize reduced metals and generate strong acids such as sulfuric acid.

Question 15

neutalophiles (neutral pH around 7)

Answer 15

are bacteria that generally grow between pH 5 and 8 and include most human pathogens

Question 16

alkaliphiles (alkaline or basic, high pH)

Answer 16

occupy the opposite end of the pH spectrum, growing best at values ranging from pH 9 to pH 11

Question 17

Aerobes

Answer 17

Some bacteria (aerobes) use oxygen as a terminal electron acceptor in the electron transport chain to extract energy trapped in nutrients and convert it to a biologically useful form

-Strict aerobes
are organisms that not only exist in oxygen but also use oxygen as a terminal electron acceptor. They grow only when oxygen is present and consume oxygen during metabolism.

Aerobes, but not anaerobes, destroy ROS with the aid of enzymes

Question 18

anaerobes

Answer 18

For many bacteria (anaerobes), including several important pathogens, oxygen is toxic

Strict anaerobes
die in the least bit of oxygen. They do not use oxygen as an electron acceptor and die because they are vulnerable to the highly toxic, chemically reactive oxygen species produced by their own metabolism when exposed to oxygen. Reactive Oxygen Species (ROS) are oxygen molecules or ions with one too few or two many electrons.

Question 19

facultative anaerobes

Answer 19

Facultative anaerobes that possess the enzymes to detoxify oxygen radicals and also the machinery for both fermentation and aerobic respiration

Question 20

aerotolerant

Answer 20

Aerotolerant anaerobes use only fermentation to provide energy but contain superoxide dismutase and catalase or peroxidase to protect them from ROS

Question 21

microaerophiles—where would you find them in a tube?, which would you find in a puncture wound vs. a superficial wound?

Answer 21

will grow only at low oxygen concentrations. They possess a decreased level of superoxide dismutase and/or catalase

Question 22

What are biofilms?

Answer 22

a mass of bacteria that stick to and multiply on a solid surface, such as a stone in a lake or a lung in a cystic fibrosis patient.

Question 23

Endospores

Answer 23

are resistant to many environmental stresses that kill vegetative cells