microbio lab quiz 3

Prokaryotes live everywhere in…

• on animal (skin)

• in animal (gastrointestinal track)

• Ice sheet

• hot spring

• etc

Names rules apply to

both already know and newly discovered organism

LPSN include

• taxonomic range, phylum, kingdom, division, domain

• rank of class, subclass, order, suborder, tribe, subtribe, family, subfamily, genus, sub genus, species, subspecies

comparison of genes via

sequence that haven’t change throughout revolution

• conserved DNA

• rRNA

auto-

create it own carbon source (inorganic)

hetero-

use enviroment for carbon sources (organic)

photo-

use light as energy souces

chemo-

use carbon as energy sources

PCR

laboratory procedure use heat stable enzyme and thermal cycler to copy and amplify specific strand of DNA

biofilm

thin, complex layer of bacteria settling on surface

biofilm often made of variety of different species

sometime only 1 bacterial species

biofilm consist of

dense matric of polysaccharides, proteins, DNA, inorganic components, channels for nutrient transportation

quorum sensing

cell use signal to communicate in biofilm

planktonic cells

single cells

biofilm can help the cell

• resistant to antibiotic

• hide from host immune defend

what types of bacteria can do biofilm

both gram negative and gram positive, (some fungi can too)

why it is hard to grown organism in lab?

required special nutrient, growth conditions, long period of time

selective media example

PIA (Pseudomonas Isolation Agar)

selective media is use for

provide select growth for target organism while inhibit the growth of undesired.

how to select media inhibit the growth of undesired organism?

• omitting certain nutrient

• adding compound to medium (dye, antibiotic)

differential media example

starch agar

differential media is use for

allow variety of bacteria to growth but enable visually distinguish among different type

ways to distinguish types on differential media

• starch present- show metabolism use of starch for carbon sources

• pH indicator - show acid production if color change

Selective-differential media example

MacConkey agar plate

selective-differential media is use for

both selective and differential properties

PIA

contain board-spectrum antimicrobial agent inhibits growth of everything but Pseudomonas strains

starch agar

can it use starch (amylose) as carbon & energy sources

• iodine added - clear area around colonies = have alpha-amylase, able to use starch

growth of organism on starch agar is ____

NOT indicative of starch utilization- need to add iodine

MacConkey agar

select for gram-negative enteric organism

• bile salt + crystal violet in medium = inhibit grown of gram-positive

differentiate lactose-fermenting enteric (coliform)

• neutral red pH in medium = produce acid - bright pink colonies - coliform

enterics

in warm blood, facultative (live w/ or w/out oxy), gram-neg, rods shape

escherichia

in human intestine

salmonella

in meat

serratia

nosocomial (hospital-acquired) inflection

alpha-amylase

• catalyze breakdown of starch

• secreted extracellularly

• active outside of cell

Heat-fixing is skipped when staining a biofilm because

extreme heat destroys the natural 3D architecture of the extracellular polymeric substance

vegetative cell

actively growing, metabolically active bacterial cell that divides and carries out normal life functions

endospore

tough, non-reproductive structure formed as a survival mechanism against harsh conditions

• handle extreme heat & UV radiation

Symbiosis

diff organism live close/interact with each other

can be permanent or transient (not required to be together to survive)

• communalistic

• mutualistic

• parasitic

commensalism

no host damage nor benefit

infection at birth/early in life

mutualism

both benefit

start out as commensalism

parasitism

host damage

at any time in life

opportunistic pathogen

start as normal, no harm but then change into harm

• E.coli is normal microbiota in GI track, but is parasitic in urinary bladder

normal microbiota can be both

commensalism and mutualism

pathogens

parasites

nodules

plant-root structure that bacteria in, help with nitrogen cycle, improve soil fertility

bacteroid

swollen, distorted bacteria cell in plant cell

bacteriophages or phages

bacteria infected by viruse

lytic cycle

1. attachment

2. penetration

3. biosynthesis - use host tool

4. maturation - assemble virions

5. release - host cell lysed

PFU

plaque-forming units

original concentration of phage formula

#PFU / (volume plated * total dilution)