micro bio- microbial growth

when nutritional requirements are met what will happen to a microbe

will enlarge in size and eventually divide

what is microbial growth?

cell division that produces new (daughter) cells and increases the total cell population

What is biofilm?

quorum sensing (how they communicate), enzyme secretion. Common indwelling devices:catheters, heart valves

give an example how environmental factors impact bacteria (E.coli)

E. coli converts from motile bacillus to filamentous nonmotile in the urinary tract.

What is budding? (yeast, fungi)

-asexual reproduction (replicate by separating from parent cell)

- The original cell elongates then develops a small outgrowth on one side

- The chromosome is duplicated and placed in the bud.

-separation from mother cell occurs.

-performed by certain fungi and some bacteria

What is spore formation?

performed by some fungi and bacteria

What can fungi be?

sexual or asexual

What can bacteria be?

asexual

Streptomyces resemble fungi because they:

Produce chains of spores on aerial hyphae-like extensions.

Which of the following best describes bacterial endospores?

A) Thin-walled reproductive structures that divide rapidly.
B) Thick-walled, nongrowing structures formed for survival.
C) Metabolically active forms that allow rapid nutrient uptake.
D) Structures found only in fungi and protozoa.

Thick-walled, nongrowing structures formed for survival.

When bacteria divide by binary fission, what do they exhibit?

exponential growth

Generation/doubling time varies among bacteria. What is the typical time?

20 minutes

normal human temp is?

37 C, 98.6 F

what temperature does water freeze at

0 C

what temperature does water boil at?

100 C

What happens at optimal temperature?

growth is highest

What happens in low temperature?

decrease enzymatic reactions

What happens at increased temperatures?

speeds up enzymatic reactions

can increase growth rate

What happens in high temperatures?

denature cell proteins (kills cell)

what temperature do psychrophiles thrive in?

-20°C and 10°C

what temperature does psychrotrophs grow in?

0-30°C, associated with foodborne illness

what temperature mesophiles grow best around?

grow best around 10°C - 50°C

associated with most pathogens

pathogenic to human

what temperature do thermophiles grow in?

40 - 75°C

associated with compost piles and hot springs

What temperature do extreme thermophiles grow in?

65 - 120 C°C

What can barophiles withstand?

high pressure of deep sea

what pH do acidophiles grow at?

pH 1 (or less) to pH 5

Where do acidophiles live?

sulfur hot springs and volcanic vents

What can acidophiles often maintain?

fairly neutral cytoplasmic pH

what raises pH in acidophiles?

proton pumps export excess protons from the cytoplasm to raise pH

What pH do neutrophiles grow best at?

pH range of 5-8

make up majority of microorganisms

What pH do alkaliphiles grow in?

basic pH range of 9-11

associated with soda lakes

What do halophiles thrive in?

high-salt environments

tolerate up to 35%

What can facultative halophiles tolerate?

higher salt but may not grow well (e.g., Staphylococcus aureus)

Where are plasmolysis/crenation found?

bacteria in high-salt environment (hypertonic)

most pathogens thrive in

low-oxygen environments within the host

What is the percentage of oxygen requirements?

21%

Inside the cell, what is some of the oxygen converted into?

reactive oxygen species (ROS)

what are the components of ROS?

superoxide ions (O2-)

hydrogen peroxide (H2O2)

What can ROS rapidly damage?

Protein and DNA

Many microbes have evolved ways to detoxify ROS (e.g, aerobes):

SOD (O2→H202) & catalase (H202→ H20 &O2)

what is FTM?

fluid thioglycolate media

-liquid media

-(lose cap) oxygen enters, decreasing oxygen %

what does obligate aerobic look like?

oxygen uses in metabolism : absolute dependence

can effectively manage reactive oxygen species? yes

What does an obligate anaerobe look like? (without)

oxygen use in metabolism? not used

can effectively manage reactive oxygen species? no

What does microaerophile look like? (small o2, less then 2%)

oxygen use in metabolism? small amounts

Can effectively manage reactive oxygen species? yes (but only low amounts)

What does an aerotolerant anaerobe look like? (tolerates O₂, doesnt grow better)

oxygen use in metabolism? not used

can effectively manage reactive oxygen species? yes

What does a facultative anaerobe look like? (use oxygen, detoxify)

oxygen use in metabolism? prefer using oxygen but can survive without it

can effectively manage reactive oxygen species? Yes, oxygen.

what are the 2 categories of organisms based on how they obtain organic carbon?

heterotrophs and autotrophs

What are heterotrophs?

require an external source of organic carbon (e.g., sugar, lipid, proteins)

What are autotrophs?

do not require an external source of organic carbon.

what do autotrophs use to convert inorganic carbon into organic carbon?

carbon fixation

What is it called when some cells get their nitrogen directly from the atmosphere?

nitrogen fixation

What are organisms that need multiple growth factors?

fatidious (picky, hard to grow)

What is it called when the necessary substances are those that a cell can’t make on its own?

growth factors

What is liquid media? (broth media)

are ideal for growing large batches of microbes: nutrients are added to purified water.

What is solid media?

are useful for isolating colonies and observing specific culture characteristics.

what is semisolid media?

is useful for motility testing

how do slants cool

cool at an angle

How do deeps cool?

cool uoright

How are solid and semisolid media at?

in slants and tubes, medium is heat sterilized

What is defined media? (often called synthetic media)

-chemically defined or precisely known composition

-Each organic and inorganic component is completely known and quantified.

What is defined media useful for?

growing certain autotrophs and some heterotrophs

What is complex media? (often called enriched media)

-contains a mixture of organic and inorganic nutrients that are not fully defined

-contains more complex ingredients (blood, milk, proteins)

- The precise quantity of every vitamin and nutrient is unknown.

What is complex media useful for?

fastidious organisms with complex growth requirements

Are urine samples, throat swabs, and fecal (stool) pure cultures? (T/F)

false, not pure cultures

What is selective media? (survives)

-single out bacteria by inhibiting growth of others (ex: MSA, EMB)

-inhibit/kill most microbes

-kills most, but ket a small population survive

What is differential media?

-media formulated to visually distinguish one microbe from another. (ex, blood agar)
-Multiple microbes grow and look different.

what is mannitol salt agar (MSA)

-selective due to its high salt content

-differentiates organisms based on their ability to ferment a sugar called mannitol

-uses a certain sugar which changes the pH why the color changes

What is a common example of a differential medium?

blood agar

What is beta hemolytic?

-break down RBC (rupture)

-no red

-clear golden halo

What is alpha hemolytic?

-partial breakdownof RBC?

-greenish/brown

-partially ruptures

what is gamma hemolytic?

-do not lyse RBC

-extra red

-no rupture of RBC

What is eosin methylene blue agar (EMB)?

-dytes eosin and methylene blue limit GRAM -POSITIVE bacterial growth

-differentiates based on ability to ferment lactose

What happens to enrichment when the temperature is cold?

-microbe does not slow growth below 37°C.

-growth continues while incubating at refrigerated and sometimes freezing temperatures

What happens to enrichment when in a hot environment?

-The microbe does not slow growth in temperatures above 37°C.

- Growth continues while incubating at 38-40°C.

What is enriched media?

A substance is added to the media to help isolate a microbe of interest.

what is an example of enriched media

buffered charcoal yeast enriched (most bacteria are killed by)

-inhibits growth in most microbes

Where are microbes suspected with charcoal-friendly microbes in a sample?

Legionella pneumophila & Campylobacter jejuni (grow well in charcoal)

What is anaerobic media?

molecular oxygen is removed from media in anymvwe od ways

What is added to an anaerobic media?

thioglycate (FTM) is added to the media

How much oxygen is anaerobic media exposed to?

21% O₂

what is an anaerobic jar?

- A sample is added to the chamber.

- A packet of oxygen-reacting chemicals is opened inside it, creating oxygen-free conditions.

What are aseptic techniques?

-methods designed to prevent introducing contamination or contaminating microbes to a patient, a clinical sample, or another healthcare setting

- Protect people and promote sample integrity

What is the streak plate technique?

is the most commonly used technique to isolate bacteria.

What is a colony?

as cells divide, their population increases to form a mound of cells

What happens in a streak plate technique?

-method dilutes a culture on an agar plate

-individual cells are thinly separated from one another over the medium's surface.

what does manual cell counting require?

-microscope

-specialized counting chamber that has a volumetric grid etched on it

What is a coulter counter?

is a machine that counts the number of cells that they pass througjh a thin tube

What is a flow cytometer?

uses a laser light to detect cells passing through a narrow channel

what is the viable plate count?

allows for direct enumeration of bacteria using agar plates

what method is used when samples are serially diluted appled to agar

spread plate or pour plate method

What are colony-forming units (CFU) per millimeter (or per gram)

reflects that sometimes a clump of cells give rise a colony

What is physical analysis?

involves staining and microscopy to observe morphological features

What is biochemical analysis?

involves a collection of media that assess metabolic properties

What are genetics methods?

help quickly identify microbes.

-probes, polymerase chain reaction (PCR) , DNA “fingerprinting,” electrophoresis separation methods

what are the methods for identifying microbes?

physical analysis, biochemical analysis, genetic methods