Test 1 Flashcards
Biofilm
community of microO working together
16S rRNA Genes
Used to create 3 domain classification, small ribosomal subunit
Microbiologists study…
Cellular, ie fungi, protists, bacteria, archaea
Acellular, ie viruses, viroids, virusoids, prions
We will study…
Bacteria, Archaea, Viruses, Viroids, Virusoids, Prions
Microbiology prompted creation of…
immunology
Antony van Leeuwenhoek (1632-1723)
First person to observe and describe microO accurately, aided in development of microscope
Spontaneous generation
living organisms can develop from nonliving or decomposing matter, popular up to 1600s
Francesco Redi (1626-1697)
disproved spontaneous generation for large animals, maggots on decaying meats from fly eggs
John Needham (1713-1781)
mutton broth -> boiled -> sealed = microO
concluded -> “vital force”
Lazzaro Spallanzani (1729-1799)
broth -> sealed -> boiled = no microO
concluded -> air carries germs
BUT maybe air supports life
Louis Pasteur (1822-1895)
Nutrient soln in flasks w/ curved necks -> boiled -> exposed to air
Disproved spontaneous generation
John Tyndall (1820-1893)
dust carries microO, sterile broth -> one neck of flask broken, other not -> broken neck growth occurs
Microbes causative in disease?
diverse evidence:
1) Agostini Bassi (1773-1856)
• disease of silkworms was caused by a fungus
2) M. J. Berkeley (ca. 1845)
• Great Potato Blight of Ireland caused by a fungus
3) Heinrich de Bary (1853)
• smut and rust fungi => cereal crop diseases
4) Louis Pasteur
• silkworm disease caused by a protozoan
Joesph Lister (1827-1912)
indirect evidence for microO cause of disease, antiseptic surgical techniques, heat sterilization/phenol lessen # infections
Thomas Eakins
Gross Clinic Painting
Agnew Clinic
Robert Koch (1843-1910)
est. relationship between B. anthracis and anthrax; used criteria developed by Jacob Henle:
injected healthy w/ material from sick
sick spleen into culture
spores into healthy mice
Now known as Koch’s Postulates
Koch’s Postulates
To prove a causal relationship between microorg. & disease:
- The microorganism must be present in every case of the disease but absent from healthy individuals
- The suspected microorganism must be isolated and grown in a pure culture
- The same disease must result when the isolated microorganism is inoculated into a healthy host
- The same microorganism must be isolated again from the diseased host
Koch’s work led to…
agar, petri dish, nutrient broth and agar, methods for isolating microO
Increased understanding of pathogens
Edward Jenner (~1798)
vaccination procedure to protect individuals from smallpox, preceded work est. role of microO in disease
Pasteur and Roux
incubation of cultures for long intervals, pathogens lost ability to cause disease “attenuated”
Transfer to healthy host protection against infection
Pasteur and coworkers
vaccines for chicken cholera, anthrax, and rabies
Emil von Behring (1854-1917) and Shibasaburo Kitasato (1852-1931)
Inactivated diphtheria toxin into rabbits, produced transferable antitoxin
developed antitoxins for diphtheria and tetanus
evidence for immunity from “soluble substances” in blood (humoral immunity)
Elie Metchnikoff (1845-1916)
discovered bacteria-engulfing, phagocytic cells in the blood, (cellular immunity)
Sergei Winogradsky (1856-1953) and Martinus Beijerinck (1851-1931)
pioneered use of enrichment cultures, selective media
soil microO
numerous interesting metabolic processes
Microbiology as a basic science…
basic biology of microO
understanding microO improved understanding of other Os
Microbiology as an applied science…
medical microbio, immunology, food and dairy microbio, pub health microbio, industrial microbio, agricultural microbio
Future of Micriobiology…
new and old infectious diseases, industrial processes, diversity and ecology, biofilms, genome analysis, microbes as model systems
Magnification
increases apparent size of specimen, calculated by multiplying magnification factors of lenses
Resolution
minimum distance that two objects can be separated from one another, and still be recognized as distinct objects rather than 1 larger “fuzzy” object
Increasing Resolution
oil: higher refractive index than air
decreasing illumination wavelength
focusing illumination light (condenser)
Illumination: Brightfield
Method of lighting the specimen from opposite the objective
appears dark against a light background
common method
usually need staining
Illumination: Darkfield
illuminationof the specimen w/o projecting light directly into the objective
used to examine specimens which cannot be distinguished from the background
unstained, living
Fixation
preservation of internal and external structures
organism is killed and firmly attached to microscope slide
heat fixing and chemical fixing
Heat fixing
preserves overall morphology (not internal structures)
Chemical fixing
protects fine cellular substructure and morphology of larger, more delicate organisms
Dyes
make cell structures more visible
increased contrast w/ background
chromophore groups + ability to bind cells
Basic dyes
positively charged
Acidic dyes
negatively charged
simple staining
single staining agent
frequently basic dyes
crystal violet; methylene blue
Differential stains
divides microO into groups based on their staining properties
gram stain
acid-fast
staining of specific structures
Gram Staining
most widely used Gm+, Gm- primary stain, crystal violet mordant, gram's iodine decolorization, etoh counterstain, safranin Gm+ Purple GM- Pink
Acid Fast staining
staining for members of genus Mycobacterium
M. tuberculosis
M. leprae
high lipid content in cell walls
Negative Staining
visualize capsules, colorless against a stained background
Spore Staining
Double staining technique
bacterial endospore vs vegetative cell
Flagellar Staining
Mordant to increase thickness
Phase-contrast light microscopy
visualizing living cells
no stain
Transmission electron microscopy
Much like brightfield, electron stream opposite to specimen
Scanning electron microscopy
More like darkfield, visualize outside of specimen
cocci (s., coccus)
Spheres
diplococci (s., diplococcus)
Pairs
streptococci
Chains of spheres
staphylococci
grape-like clusters of spheres
tetrads
4 cocci in a square
sarcinae
cubic configuration of 8 cocci
bacilli (s., bacillus)
rods
coccobacilli
very short rods
vibrios
“comma” shaped
spirilla (s., spirillum)
rigid helices
spirochetes
flexible helices
filamentous
form hyphae
mycelium
branched hyphae
unusual shapes
archaea
Bacterial cell envelope
plasma membrane + surrounding layers
Bacterial plasma membrane
separation of cell from its environment selectively permeable crucial metabolic processes - respiration, lipid synthesis, (some) photosynthesis membrane receptors ex. phosphatidylenthanolamine + hopanol
Bacterial cell wall
shape protection may contribute to pathogenicity may protect from toxic substances Peptidoglycan aka murein
Periplasmic space
gap between plasma membrane and cell wall in Gm+ or between plasma membrane and OM in Gm-
periplasmic + exoenzymes
Periplasmic enzymes
periplasm of Gm- nutrient aquisition electron transport peptidoglycan synthesis modification of toxic compounds
Exoenzymes
secreted by Gm+ bacteria
similar functions to periplasmic enzymes
Cell Wall and osmotic protection
osmotic lysis - hypertonic solns, cell wall protects
plasmolysis - hypertonic solns, cell wall can’t protect
Bacterial cell wall and Gram staining
thought to involve constriction of the thick peptidoglycan layer of gram positive cells
Thinner peptidoglycan layer of gram-negative bacteria does not prevent loss of crystal violet
Bacterial cell wall structure: peptidoglycan
polysaccharide formed from peptidoglycan subunits
backbone: alternating N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)
most Gm- walls z shaped bridge
most Gm+ walls pentaglycine bridge
Helical cross linking for strength
Gram-positive cell envelope
No OM
Cell wall primarily peptidoglycan may also contain teichoic acids
lipoteichoic acid anchors to PM
Some Gm+ bacteria has layer of proteins on surface of peptidoglycan
Gram-negative cell envelope
OM: lipids, lipoproteins, and lipopolysaccharide (LPS) no teichoic acids
cell wall: thin peptidoglycan layer surrounded by OM
Gm- cell envelope: Braun’s lipoproteins
connect OM w/ peptidoglycan
Gm- cell envelope: adhesion sites
direct contact between plasma membrane and OM, may allow direct movement of material into cell
Gm- cell envelope: lipopolysaccharides (LPS)
O antigen: protection from host defenses, immunogenic
core polysaccharide: contributes to negative charge on cell surface
lipid A: helps stabilize OM structure, can act as an exotoxin
exotoxin
pathogenic when released, by death or cleavage
endotoxin
intact bacteria is pathogenic
Gm- cell envelope: OM
protective membrane
more permeable than plasma membrane
presence of porins and transporters
Layers outside the cell wall
Typically pathogenic have these Capsules, Slime Layers, S-layers protection from host defenses protection from harsh environmental conditions attachment to surfaces protection from viral infection or predation by bacteria protection from chemicals in environment motility protection against osmotic stress
Capsules
usually polysaccharides
well organized; not easily removed
resist phagocytosis
Slime layers
polysaccharides
diffuse, unorganized; easily removed
S-layers
structured layers of protein or glycoprotein
common in Archaea
glycocalyx
eukaryotes
polysaccharide network
like capsule/slime layer
Archaeal cell envelope
different from bacterial both molecularly and organizationally
methanochondroitin = cell wall like
pseudomurein
Archaeal Plasma membrane
composed of unique lipids
some have monolayer
some bilayer
Archaeal Cell Wall
Gm stain not useful
lack peptidoglycan
The cytoplasmic matrix
substance between membrane and nucleoid
packed with ribosomes and inclusion bodies
highly organized; cytoskeleton-like organization/function
Bacterial cytoskeleton
homologs of eukaryotic cytoskeleton components have been identified.
Tubulin homologs
FtsZ - cell division
BtubA/BtubB - unknown
Actin homologs
FtsA - cell division
MamK - positioning magnetosomes
MreB/Mbl - maintains cell shape, segregates chromosomes, localizes proteins
Intermediate Filament homologs
CreS (crescentin) - induces curvature in curved rods
Unique bacterial cytoskeletal proteins
MinD
ParA
Bacterial intracytoplasmic membranes
plasma membrane infoldings
anammoxosome
plasma membrane in-foldings
found in many photosynthetic bacteria, and bacteria with high respiratory activity
may be aggregates of spherical vesicles, flattened vesicles, tubular membranes
anammoxosome
membrane-bound organelle
anaerobic ammonia oxidation
unique to Planctomycetes
inclusion
aggregation of organic or inorganic material
storage inclusions
microcompartments
other inclusions
Storage Inclusions: Carbon
glycogen inclusions
poly-beta-hydroxybutyrate inclusions
Storage Inclusions: phosphate
polyphosphate granules
Storage Inclusions: sulfur
sulfur globules
Storage inclusions: nitrogen
Cyanophycin granules
cyanobacteria
large polypeptides not from ribosomes, equal quantities of arg and asp
Microcompartments: carboxysomes
function other than metabolic stockpile
cyanobacteria, CO2 fixing
Concentration of CO2; enzyme localization
ribulose-1,5-bisphosphate carboxylase (RUBISCO) fixes carbon in calvin cycle