Microbio Exam 1

microscopic

too small to see with the naked eye (about 0.5mm)

microbes

account for 50% of the earths biomass

plants= 35%

animals= 15%

how does environmental microbiology affect our lives?

• recycle carbon, nitrogen, phosphorus, sulfur

• sewage treatment

• degrade pesticides and herbicides.

• bioremediation (cleaning up toxic waste)

how does food microbiology affect our lives?

• Microbes are used in food production (ex. yeast)

• cause spoilage

• crop damage

how are microbes used in production of medical, agricultural and industrial products?

• antibiotics (penicillin)

• steroids

• organic solvents and acids

• enzymes

• animal protein products

how are microbes used in genetic engineering and biotechnology?

• agricultural applications

• protein productions gene therapy

who was Francesco Redi?

• 1668

• disproved spontaneous generation

• maggots developed on meat only when flies had direct access to lay eggs (exposed to open air)

• not accepted by everyone at the time

who was Antony van Leeuwenhoek?

• 1674 - “discovered” microorganisms

• developed his own hand held microscope

• magnify up to 300x

• important because of spontaneous generation

who was Louis Pasteur?

• 1800’s

• MOST significant to refute spontaneous generation

• swan-necked flasks

• broth remained sterile unless exposed to airborne microorganisms

• vaccines for rabies

who was Robert Koch?

• 1870’s - 1884 - links infectious agent to infectious disease with Koch’s 4 Postulates

• led to the Golden Age

• pure culture; important because it allowed study of individual microbes

• identified microbes that cause anthrax, cholera, and tuberculosis

who was Fracastoro?

• 1546

• first to suggest that some “unseen” something was getting people sick (early idea of Germ theory)

who was Semmelweis?

• 1847

• noticed a high mortality rate in hospitals vs. with midwives

• doctors weren’t washing their hands between activities

• handwashing with chlorinated lime water drastically reduced these deaths

who was John Snow?

• 1848

• cholera was transmitted through contaminated water

who was Joseph Lister?

• 1867

• handwashing during surgery

• using carbolic acid (phenol) spray disinfectant/antiseptic

what are Koch’s postulates?

1. microorganisms present in disease cases, absent in healthy animals

2. microorganisms can be isolated from diseased animals

3. disease can be reproduced by inoculation of healthy animal with cultured organism

4. organism can be re-isolate from experimentally infected animal and returned to culture (pure)

• dependent on microscopes and culturing techniques

who was Carolus Linnaeus?

• 1735

• created taxonomy

• 3 kingdoms: plants, animals, minerals

• lasted only about 100 years

what is taxonomy?

• classification, identification, and nomenclature based on shared characteristics

• continually evolving fields

what is the taxonomic hierarchies?

Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species

who was Whittaker?

• 1969

• added fungi

• 5-kingdom system (Plants, Animals, Fungi, Protista, Monera)

• based on physical characteristics

who was Carl Woese?

• 1977 - added the third domain of life

• defined archaea as prokaryotic

• based on ribosomal RNA sequence data of 16S ribosomal RNA (rRNA) in prokaryotes; 18S rRNA in Eukaryotic cells

• 1990 - proposed separate domain of archaebacteria: bacteria, archaea, and eukarya

who was Bergey?

• 1923 - established manual of systemic bacteriology

what is identification/naming important?

• important to identify pathogens in order to appropriately diagnose and treat pathogens

• identify foodborne pathogens and sources

• study and communication

Prokaryotes consist of

• bacteria and archaea

• extremely diverse

• archaea are often extremophiles- can live in extreme conditions

Bacterial Shapes

• coccus: sphere

• bacillus: rod

• vibrio: comma

• coccobacillus: oval

• spirillum: squiggle

• spirochete: curly

eukaryotes

• protozoa, algae, fungi, some multicellular parasites

• single or multicellular

• have a true nucleus

• contain membrane-bound organelles

• cytoskeleton

• they are harder to treat: they are similar to our cells

protist

• most are free living

• most are harmless

viruses

• nucleic acid + protein

• electron microscope to see a virus

• NOT on the tree of life bc they don’t have ribosomes and are not completely living

prions

infectious proteins

relative sizes

• atom: 0.1nm

• lipids, protein: 1nm - 10nm

• polio virus: a little more than 10nm

• flu virus, smallpox virus: 100 nm +

• bacteria & mitochondria: 1 um

• red blood cell: 1um - 10um

• animal & plant cell: 10um - 100um

• human egg, pollen: 100um +

• frog egg: 1 mm

biogenesis:

all cells come from other cells

who was Robert Hooke?

• 1665

• modern cell theory

• noticed fungi has a lot of different structures

• invented compound microscope (more than 1 lens)

• less powerful microscope than Leeuwenhoek

• could observe single cells

• reason for the term “cell”

who was Matthias Schleiden?

• 1838

• studied plants and their cell structures

who was Theodor Schwann?

• 1839

• observed cells in animal tissue

who was Robert Remak?

• 1852

• provided evidence that cells are derived from other cells based on cell division

who was Rudolf Virchow?

• 1855

• popularized cell theory in an 1855 essay entitled

“Cellular Pathology.”

key difference between prokaryotic vs. eukaryotic

• Prokaryotes – NO membrane-bound nucleus

• Eukaryotes - a membrane-bound nucleus

eukaryotic cells:

• more complex than prokaryotic

• membrane bound organelles

prokaryotic cells:

• bacteria and archaea

• unicellular

• heterogenous

Prokaryotes cell shape

• cell wall maintains the shape

• cell wall is a rigid structure

• cell wall protects cells from changes in osmotic pressure

• many antibiotics can disrupt the cell wall

pleomorphism:

variation in a cell shape and size within a single species

arrangement of cells

• chains- cells are in pairs or chains

• packets/sarcinae- two or three planes of division

• clusters- cells are in grape-like clusters

isotonic solution:

there are the same amount of solutes inside and outside the cell

hypertonic solution:

• more solutes outside the cell SO water leaves the cell

• plasmolysis = shrinking

hypotonic solution:

• more solutes inside the cell SO water moves into the cell

• swelling and lysis

crenation:

• cell shrivels up

• occurs in cells that lack a cell wall

plasma membrane:

• structure- phospholipid bilayer

• functions- provide sits for energy reactions, nutrient processing and synthesis, passage of nutrients & discharge of wastes

simple diffusion

• molecules move from higher concentration to lower concentration

• small hydrophobic molecules, gases, water

facilitated diffusion

• require transport proteins

• charged molecules, large molecules

active transport:

• molecules move against a concentration gradient

• requires transport proteins and ATP

peptidoglycan & structure

• unique to the cell wall of bacteria

• ONLY in bacteria not archaea

• composed of alternating NAG and NAM sugar chains cross-linked by peptide bridges

• Gram-positive – crosslinking via tetrapeptide chains and peptide interbridges (pentapeptide chains)

• Gram-negative – crosslinking via tetrapeptide chains

what molecules interfere with peptidoglycan?

• antibiotics like penicillin

• antimicrobial chemicals like lysozymes breaks its glycan backbone

  
  

Gram positive bacteria

• thick layer of peptidoglycan with embedded teichoic acid external to the plasma membrane.

• retains the stain in a gram test

• fully permeable, many small molecules

• some produce mycolic acid

teichoic acid

helps anchor the cell wall

acid fast cells

• mycolic acid- coats the cell wall

• mycobacteriaceae - tuberculosis are in the genus of this bacteria

Gram negative bacteria

• more complex than gram+

• thin layer of peptidoglycan

• outer membrane- bilayer composed of phospholipid and lipopolysaccharide

• may be barrier to some antibiotics

Lipopolysaccharide (LPS):

• endotoxin

• lipid A- leads to fever, septic shock (toxic component)

• O-antigen- varies among species

Sepsis

• a systemic inflammatory disease

• high morbidity and mortality

• common sources of sepsis are bacterial pneumonia,

  urinary tract infections, and abdominal infections

• can lead to host tissue injury, organ failure, and death

Bacteria lacking a cell wall

• variable shapes

• can’t be killed w/ cell wall synthesis inhibitor

  • not killed by penicillin or lysozyme (no target)

• smallest of the bacteria

• M.pneumoniae- causes walking pneumonia

Glycocalyx

• an outer gelatinous polymer coating

• helps with adhesion

• biofilm formation

capsules

• organized layer of polysaccharides.

• virulence factor by inhibiting phagocytosis

biofilms

• lots of cells stuck together

• protects from attacks of infections

• over 65% of human infections are biofilm related

• prevent antibiotic penetration

external structures

• flagella- long protein structures made of flagellin used for cell motility

• fimbrae- short, numerous filaments used for surface attachment

• pili- hollow, short, thick protein filaments; attachment and conjugation (for transfer of DNA between cells)

• not all bacteria will make the external structures

Bacterial Chromosome

• bacteria have ONE chromosome

• circular, double-stranded DNA

• contains all genetic info

• located in nucleoid region

• nucleoid IS NOT a membrane bound structure

• NAP- nucleoid associated proteins

plasmids

• bonus DNA

• independent

• double stranded

• not really essential

• any prokaryotes can carry plasmids

• RESISTANCE to antibiotics

• can be transferred between bacteria

Ribosomes

• protein synthesis

• prokaryotic ribosomes- 70S (antibiotics bind to); 16S RNA

• eukaryotic ribosomes- 80S (protein synthesis inhibitors find nothing to bind to); 18S RNA

Inclusions

• allows bacteria to store components they might need later

endospores

• protect genome

• thick walled & resistant (hard to kill)

• protects cells until environment returns

• long lived (100 years)

• not all cells produce this

vegetative cells

• can be killed very easily

• actively growing and dividing

C. diff

• form spores

• can be transferred (sinks, toilets, high touch surfaces)

why is staining important?

• stains enhance the contrast of microbes

• most microorganisms are transparent/translucent

• provides info about the bacteria

simple staining

• uses one dye; all cells appear the same color

• basic dyes (+charged dye; stains whatever is neg. charged)

  • bacterial cells have an overall negative charge

• acidic dyes (-charged dye; stains whatever is positively charged)

Gram stain

• most common for bacteria

• Reflects differences in the chemical structure of the cell walls of the groups of bacteria

Gram-variable

• bacterial species that stain inconsistently

• can result in incorrect results

capsule stains

• protective outer coating

• some bacteria and yeast produce this

• virulence factors

• protect bacteria from attacks by phagocytes of the immune system

• background has color

endospore stains

• uses heat to drive malachite green into resistant endospores

• after decolorization, the cell is counterstained with safranin

• important clinical genera that are endospore formers:

  • bacillus

  • clostridium

  • clostridioides

flagella stains

• based on the # and arrangement of their flagella

• coat the flagella with a mordant; thickens the flagella, allowing them to be seen with microscopy

brightfield microscopy

• most common

• observing stained samples

• dark, true color image on a bright background

dark microscopy

• live, unstained, or low-contrast transparent specimens

• unstained cells