MIBO 3500 Exam 1 Terminology

Three microbial size contradictions

1. Supersize microbial cells

2. Microbial communities

3. Viruses

Robert Hooke

Coined the term “cell”

Antonie van Leeuwenhoek

Discovered bacteria: “small animals”

Francesco Redi

Argued against spontaneous generation using meat in a cover and maggots

Lazzaro Spallanzani

Argued against spontaneous generation using boiled water in a flask

Louis Pasteur

Founder of medical microbiology. Argued against spontaneous generation using a B. Swannecked flask

Three aspects of Germ Theory

1. Chain of infection (transmission)

2. Pure culture (from a single parental cell)

   1. Colonies (population grown from a single cell)

Robert Koch

Studied link between specific microbe and disease

Koch’s Postulates

1. Microorganism is present in every case of disease and absent from healthy organisms

2. Microorganism is isolated and grown in a pure culture

3. The same disease results when the microorganism is inoculated in a healthy host

4. The same microorganism can be isolated from a 2nd diseased host

Barry Marshall

Suspected a link between bacteria and stomach ulcers, but couldn’t prove his theory because he couldn’t fulfill Koch’s postulates

Florence Nightingale

Used medical statistics to demonstrate the significance of mortality due to disease

Alexander Fleming

Penicillin

Florey and Chain

Purified penicillin

Winogradsky

Demonstrated importance of bacteria in geochemical cycling (nitrogen cycling)

Resolution

Ability to distinguish small objects close together

Magnification

Enlarged image of an object

Contrast

Difference in color intensity between an object and its background

Refraction

Bending of light as it passes through an object that slows its speed

Detection

Ability to determine the presence of an object

Fluorophores

Chemical compounds that absorb/emit light of specific wavelengths (dye or protein)

Specimen Staining

Adds stain to sample, increasing visibility, preserving sample, and highlighting morphological features

Fixation

Kills specimen, internal and external structures preserved

Basic Dyes

Have positive charge, bind to negatively charged molecules

Acidic Dyes

Have a negative charge, bind to positively charged molecules

Simple Stains

Color added to cells but not background

Differential Staining

Stains one kind of cell but not another

Gram stain

Used for general cell wall properties

Gram stain steps

1. Fix sample

2. Crystal violet

3. Iodine mordant

4. Alcohol

5. Safranin counterstain

Pili

• Long and thick

• “Sex pili”

• DNA transfer

• Motility

Fimbrae

• Short and thin

• Evenly distributed at poles

Capsule

• Outer layer composed of polysaccharides

• Adheres to surfaces

• Resistant to phagocytosis/immune system

• Thick = hard to destroy

Flagellum

Rotary motor propells

Cell Membrane

Defines existence of a cell

Membrane reinforcement agents

Eukaryotes: Cholesterol

Bacteria: Hopanoids or hopanes

Diffusion

Small uncharged molecules permeate the membrane

Protein transporters

Polar/charged molecules transport passively or actively

Nucleoid

Where DNA is organized in prokaryotic cells

Sacculus

Cell wall - determines shape and rigidity

NAG and NAM

Alternating sugard used in peptidoglycan structure of cell wall

Transpeptidase

Cross-links amino acids in peptidoglycan - targeted by penicillin

Teichoic acids

Thread multiple layers of peptidoglycan together

Genus Mycobacterium

Has 2 layers of membrane

Genus Mycoplasma

Has 3 layers of membrane

Exopolysaccharide

“EPS” made of DNA, sugars, and proteins

Quorum Sending

Microcolony communication

Essential Nutrients

Nutrients a microbe cannot make for itself and must gather from the environment. Directly affects level of growth.

Macronutrients

Needed in large quantities:

• Carbon

• Nitrogen

• Oxygen

Micronutrients

Needed in small quantities:

• Manganese

• Copper

• Cobalt

Types of media

1. Enriched media

2. Selective media

3. Differential Media

Enriched media

Complex media to which specific blood components are added

Selective media

Favor the growth of one organism over another

Differential media

Exploit differences between two species that grow equally well

Environmental adaptation

Describes how some organisms are so well adapted to their natural habitat that we don’t know how to grow them in the lab

• 99.9% of microbes

If a microbe is unculturable, how do we know it exists?

1. Observe under a microscope

2. Collect DNA/RNA samples from environmental

Rickettsia prowazekii

• Agent of Typhus Fever

• Endemic in flying squirrels

• Transferred to humans via lice poop

Heterotrophs

Rely on other organisms for carbon

Autotrophs

Able to reduce CO2 on their own

Phototrophy

Get energy from light

Chemotrophy

Get energy from RedOx reactions:

1. Lithotrophy

2. Organotrophy

Lithotroph

Inorganic electron donors

Organotroph

Organic electron donors

Photoheterotroph

Gets its energy from sunlight and relies on reduced carbon from other sources

Proton motive force

An electronchemical potential formed by H+ gradient and charge differenceF

F0 Component

Spans membrane and acts as a channel

F1 Component

Located in the cytoplasmic area and allows for conversion of ADP to ATP

Nitrogen fixers (nitrifiers)

Convert atmospheric nitrogen into a usable form (ammonia or ammonium)

Nitrifying bacteria

Oxidize usable nitrogen into nitrates

Denitrifying bacteria

Oxidize nitrates back into atmospheric nitrogen

Rhizobium

Infects legume roots in a beneficial bacterial infection

Binary fission

One parent splits into two equal daughters

Nt = N₀ × 2ⁿ

Nt: total number of cells

N₀: original number of cells

n: rounds of binary fission

Lag phase

• No binary fission occurring at all

• Metabolically active with no cell increase

Log phase

• Most susceptible to antibiotics

• Population doubles for every generation

• Cellular constituents made at constant rates (balanced growth)

Stationary phase

• Growing at an equal rate as death

• New cells made at the same rate as old cell death

Death phase

• Prolonged decline as 1% of the population mutates according to the environment

• Can reenter log growth in the right conditions

Primary metabolites

• amino acids

• nucleic acids

• simple lipids

Secondary metabolites

• antibiotics

Continuous culture

defined by all cells achieving a steady state, allowing for a detailed study of bacterial physiology

Normal growth conditions

1. sea level

2. 20^oC - 40^oC

3. Neutral pH

4. 0.9% salt with ample nutrients

Microbes and temperature

Microbes can’t regulate cellular temperature. Enzymes have optimal temperature for function.

• High temperatures destroy proteins

• Low temperatures solidify membranes

Psychrophiles

• 0-20

• Membrane remains semi-fluid in cold (freezing temperature decreased by accumulated solutes)

• Arctic environments have poor nutrients and high UV - anomaly bacteria

Mesophiles

15-45

Thermophiles

• 40-80

• More hydrogen bonds

• DNA stabilized by DNA binding proteins

Hyperthermophiles

• 65-120

• Ex: Taq DNA polymerase

Barophile

Live in up to 1000 atm, but very hard to study because we struggle to replicate the extreme pressure

Hypertonic medium

• Water will leave cell to equalize solute concentration across membrane

• Cellular osmotic concentration increases via synthesizing/importing solutes

Hypotonic solution

• Water will enter cell

• Pressure-sensitive channels allow solutes to leave cell

Aquaporins

• Membrane-channel proteins that allow water to traverse the membrane faster than diffusion

• Protect cells from osmotic stress

Halophiles

Prefer high internal sodium concentration

Halobacterium

• Archaeal organism

• Pink pigment protects it from UV rays

Aerobes

Grow in atmospheric oxygen

Obligate aerobe

Requires O₂

Microaerophile

Requires O₂ at low concentrations

Anaerobes

Grow in absence of O₂

Obligate anaerobe

O₂ is toxic because they can’t destroy reactive oxygen species (ROS)

Facultative

Doesn’t require O₂, but prefers it

Aerotolerant anaerobe

Grows equally well with or without O₂

Neutralophiles

Grow in pH 5-8

Acidophiles

Grow in pH 0-5

Alkaliphiles

Grow in pH 9-11