Block B Flashcards
how much peptidoglycan in gram + cells
90%
what shape is coccus
spherical or ovoid
what shape is rod
cylindrical
what shape is spirillum
spiral
mycobacterium
- rod shaped
- acid fast due to mycolic acid in cell wall
filament actinobacterium
- inhabits soil
- makes a lot of anti-cancer drugs
major gram positive groups
actinobacterium, mycobacterium, firmicutes
Tenericutes : mycoplasms key feature
lacks cell walls (cant control its membrane)
- parasites that inhibit animals and plants
key features of lactobacillales
- fermentative bacteria that produces lactic acid (yoghurt)
- rod shaped and grows in chains
- resistant to acidic conditions
streptococcus
- coccus shaped, gram-positive
-bacteria commonly found on the skin or in the throat
Staphylococcus
gram-positive
These germs can live on contaminated implanted medical devices and improperly cleaned needles
coccus shape
Anthrax
-spores are difficult to kill
-gram-positive
-rod shaped
-It occurs naturally in soil
-People can get sick with anthrax if they come in contact with infected animals or contaminated animal products
Three forms of anthrax
cutaneous, gastrointestinal, inhalation
AB toxins
toxins with intracellular target that have 2 functionally distinct regions
tenericutes: mycoplasmas
Lack cell walls
Some of the smallest organisms capable of autonomous growth
Parasites that inhabit animal and plant hosts
Key components of peptidoglycan are missing
firmicutes- lactobacillales
Fermentative bacteria that produce lactic acid
Lactobacillus Rod-shaped and grow in chains
Common in dairy products
Sauerkraut
Resistant to acidic conditions
Grow in pH as low as 4
clostridium
Lacks a respiratory chain; anaerobic
produce ATP by substrate level phosphorylation
Metabolism of pair of amino acids
Mainly found in anaerobic pockets in the soil
Also lives in mammalian intestinal tract
Some species are pathogenic; diseases include botulism, tetanus, and gangrene
what are AB toxins
toxins with intracellular target that have two functionally distinct regions (A & B):
A has enzymatic activity
B is responsible for host cell binding or entry of A unit to cell
AB Toxins can operate in two ways
-Single polypeptide that is proteolytically cleaved at a later stage
-Separate polypeptides that subsequently assemble
4 gram positive phyla
Proteobacteria, actinobacteria, firmicutes, bacteroidetes
Gram stain
Add crystal violet, all cells purple, add iodine, all cells still purple, decolourise and gram positive will remain purple and gram negative are colourless, add safranin and gram positive are purple and negative are pink
Gram positive cell wall
contain 90% peptidoglycan, so is very thick and not easily penetrated by the alcohol, often have teichoic acids in the cells wall
Corynebacterium
diphtheria and glutamicum
Mycobacterium
tuberculosis, leprae
Yogurt
mixed culture of streptococcus salivarius subspecies thermopiles and lactobacillus delbrueckii subspecies bulgaricus
enterococcus
UTI, bacteremia, endocarditis, diverticulitis, meningitis
Streptococcus species
dental plaque
streptococcus viridans
scarlet fever
Streptococcus pyogenes
strep throat, necrotising fasciitis
Staphylococcus
epidermis usually found on skin, MRSA
Methiailin resistant s.aureus
resistant to a wide range of antibiotics (Superbug)
endospore forming
Bacillus and Clostridium
Clostridium
botulism, tetanus, gangrene
Anthrax
cutaneous, gastrointestinal, inhalation, posses both a capsule and S layer
AB toxins
toxins with intracellular target the have 2 functionally distinct regions, A is enzymatic and B is responsible for host cell binding or entry of A unit
O antigen
lipopolysaccharide
K antigen
capsule
H antigen
flagellen
Pillus
a hairlike extension that aids in communication and exchange of genetic material in prokaryotes
Proteobacteria
A diverse clade of gram-negative bacteria that includes five subgroups known as alpha, beta, gamma, delta, and epsilon.
Alphaproteobacteria orders
Rhizobiales, Ricketsiales, Rhodobacterales, rhodospirillales, caulobacterales, sphingomonadales
Betaproteobacteria orders
Burkholderiales, hydrogenophilales, methylophilales, niesseriales, nitrosomonadales, rhodocyclales
Gammaproteobacteria - Enterobacteriales, key genera
Enterobacter, Escherichia, Klebsiella, Proteus, Salmonella, Serratia, Shigella
mixed acid fermenters
Escherichia, Salmonella, Shigella, Proteus
Butanediol fermenters
Enterobacter, Klebsiella, Serratia
Deltaproteobacteria key genera
bdellovibrio, myxococcus, desulfovibrio, geobacter, syntrophobacter
Epsilonproteobacteria
Campylobacter jejuni
Biofilms
assemblages of bacterial cells adhered to a surface and enclosed in an adhesive matrix excreted by the cells
Direct isolation
Use selective and/or differential agar to isolate a single colony
Enrichment culture
a culture medium used for preliminary isolation that favors the growth of a particular microorganism
Direct culture
a primary culture; a culture grown by inoculating patient specimens directly onto the culture medium.
Direct counting
counting each individual cell using a heamocytometer
Viable cell counts
measurement of living, reproducing population
Most probable number
A statistical method of measuring bacterial growth used when samples contain too few organisms to give reliable measures by the plate count method
Oligotrophs
microbes that grow continuously but at low levels of activity
Copiotrophs
microbes that exist primarily in a resting phase with brief periods of activity
Viable but non culture bacteria
bacteria in a very low metabolically active state and cant grow on standard growth media
Zone of inhibition
lawn of indicator organism, filter paper disk soaked in test compound
minimun inhibitory concentration (MIC)
the lowest concentration of a specific antimicrobial medication needed to prevent the visible growth of a given bacterial strain in vitro
Bioremediation of organic pollutants - uranium
uranium contamination of groundwater has occurred where uranium has been processed or stored, some bacteria can convert U6+ to U4+
Bioremediation of organic pollutants-hydrocarbons
organic pollutants can eventually be completely degraded to CO2 by microbes, hydrocarbon degrading bacteria attach to oil and decompose
What is the difference between gram positive and gram negative membranes
Gram positive have a thick peptidoglycan layer and no outer lipid membrane
What is lipoteichonic acid?
Teichonic acids that are covalently bound to membrane lipids
Actinobacteria
Gram positive
High G-C content within genome
Largest and most complicated groups of bacteria
Mycoplasma
Tenericutes - gram positive
Some of the smallest organisms capable of autonomous growth
Lack cell walls
Pleomorphic
Groups of cells of the same species are very different from each other
Lactobacillus
Firmicutes
Fermentative bacteria that produces lactic acid from lactose
Used within the food industry extensively
Streptococcus
Gram positive
Important for the production of buttermilk, silage and other products
Staphylococcus
Commonly found in humans and animals
S.aureus is associated with many pathological conditions
Bacillus, Clostridium and sporosarcina
Gram positive bacteria with low GC content
What are the three forms of anthrax
Cutaneous
Gastrointestinal
Inhalational
What is unusual about anthrax toxin
It has three toxin subunits
2A unit and 1B unit
Extracellular components of gram negative bacteria
Capsule
Fimbriae
Flagella
Pilus
Fimbrae
Extracellular component of gram negative bacteria that allows attachment to surfaces
Pilus
Extracellular component that allows gram negative bacteria to share genetic info
Proteobacteria is sub-divided into 5 classes
Alpha
Beta
Delta
Gamma
Epsilon
Gammaproteobacteria contains many pathogen organisms such as
Escherichia
Salmonella
Shigella
Klebsiella
Ecoli morphology
Straight rods
Pseudomonad aeruginosa
Gammaproteobacteria that causes cystic fibrosis
Two ways to isolate microbes from the environment
Direct isolation
Enrichment culture
How is a most probable number calculated
Serial dilution is carried out until final tube shows no growth
Copiotrophs
Microbes that exist primarily in a resting phase with brief periods of activity
Why would a bacteria be viable but nonculturable
Bacteria is in a state of very low metabolic activity
They do not divide
