Chapter 7

studied byStudied by 83 People
0.0(0)
Get a hint
hint

Microbial growth

1/134

Tags & Description

Studying Progress

New cards
134
Still learning
0
Almost done
0
Mastered
0
134 Terms
New cards

Microbial growth

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

New cards
New cards

What percentage of bacteria species can be cultured in the laboratory?

1%

New cards
New cards

What happens when nutritional requirements are met?

A microbe will enlarge in size and eventually divide

New cards
New cards

Bacterial growth

Increase in number of cells

New cards
New cards

How is bacteria grown in the laboratory?

Usually grown as pure, single-species cultures

New cards
New cards

How do bacteria live in nature?

Intermingle and lives side by side with arches and eukaryotes

New cards
New cards

escherichia coli

a species of bacterium normally present in intestinal tract of humans and other animals; sometimes pathogenic- converts from a motile bacillus shape to a filaments non-motile form during urinary tract infections

New cards
New cards

Biofilm formation

Occurs when free-floating (planktonic) bacteria adhere to a surface

New cards
New cards

Places for biofilm

Indwelling devices (catheters, heart valves)

New cards
New cards

Binary Fission

Occurs in most prokaryotes; involves dividing a single cell into two cells; asexual process

New cards
New cards

Process of binary fission

  1. Before dividing, cell elongates and the chromosome is replicated

  2. Parent cell begins to pinch off at the middle

  3. Partition (septum) in the center becomes complete

  4. Creates 2 genetically identical daughter cells

New cards
New cards

Generation Time

Time required for a cell to divides (20 minutes to 24 hours)- time diverse. Depends on the species and conditions

New cards
New cards

Doubles the number of cells each generation

Binary fission

New cards
New cards

What impacts how fast a microbial population increases?

The nutrient available

New cards
New cards

Generation time for E.coli

20 minutes

New cards
New cards

Generation time for Mycobacterium Tuberculosis

15-20 hours

New cards
New cards

Calculation for generation time

Generation times (in minutes)= Growth time (in minutes)/number of generations

New cards
New cards

As bacteria divide by binary fission what do they exhibit?

Exponential growth

New cards
New cards

Number of growth phases for bacteria

4 growth phases when cultured using a closed pure batch system

New cards
New cards

Bacteria growth phases detected

By counting the number of viable cells

New cards
New cards

Phase one: lag phase

Delay that occurs while cells adjust to their new environment

New cards
New cards

Endospores occur

Bacteria in a starving environment get endospores

New cards
New cards

Phase two: Log phase (endospores)

Period of rapid exponential growth

New cards
New cards

Phase three: Stationary phase

Nutrients are depleted, waste accumulates- population growth rate levels off

New cards
New cards

Phase Four: Death phase

Critical point of waste buildup and decrease nutrients, the cells begin to die; rate of cell death is exponential; small number of the cells survive by adapting to the waste and by feeding off dead cells

New cards
New cards

Low temperature

Decrease enzymatic reactions

New cards
New cards

Increased temperature

Speeds up enzymatic reactions; can increase growth rate

New cards
New cards

High temperatures

Denature cell proteins (kills cell)

New cards
New cards

Thermophile

Grow around 40C-75C; associated with compost piles and hot springs

New cards
New cards

Psychrophile

Cold- thrive between- 20C and 10C

New cards
New cards

Mesophile

Grow best around 10C-50C; associated with most pathogens

New cards
New cards

Maximum temperature

Highest temperature supports growth

New cards
New cards

Minimum temperature

Lowest temperature that supports growth

New cards
New cards

Optimal temperature

Temperature where cellular growth is highest

New cards
New cards

Human pathogen

Would be a mesophile

New cards
New cards

Psychrotrophs

Grow at about 0-30C; associated with food borne illness

New cards
New cards

Extreme thermophiles

Arches- grow around 65C-120C

New cards
New cards

Extremes in pressure

High temperature environments

New cards
New cards

Barophiles

Can withstand the high-pressure environment of the deep sea

New cards
New cards

Acidophilus (acidic environment)

Grow at pH 1 or less to pH 5 Live in areas such as sulfur hot springs and volcanic vents Often maintain a fairly neutral cytoplasmic pH Proton pumps export excess protons from the cytoplasm to raise pH

New cards
New cards

Neutralophiles

Grow best in a pH range of 5-8 Make up the majority of microorganisms

New cards
New cards

Alkaliphiles

Grown in the basic pH range of 9-11 Associated with side lakes

New cards
New cards

Halophiles

Thrives in high-salt environments Tolerate up to 35% Associated with the Dead Sea and the Great Salt Lake of Utah

New cards
New cards

Facultative halophiles

Tolerate higher salt but may not grow well Example: staphylococcus aureus

New cards
New cards

Bacterial cytoplasm

80% water

New cards
New cards

Normal cells

Undergo plasmolysis

New cards
New cards

Must overcome the osmotic stress of a higher-salt environment- keep high concentrations of organic materials and ions in their cytoplasm

Halophiles

New cards
New cards

Low oxygen levels

Beneath the soil or within silt deposits in lakes and oceans- most pathogens thrive in low-oxygen environments within the host

New cards
New cards

Inside the cell, some of the oxygen is converted

Reactive oxygen species (ROS)

New cards
New cards

Reactive oxygen species (ROS)

Superoxide ions (o2-) Hydrogen peroxide (H2O2)- Can rapidly damage proteins and DNA

New cards
New cards

superoxide dismutase

Converts reactive superoxide ions to hydrogen peroxide

New cards
New cards

Catalase

Converts the hydrogen peroxide to water and oxygen

New cards
New cards

Obligate aerobes

Absolute dependence on 02 fro cellular processes

New cards
New cards

Microaerophiles

Use only small amounts of o2 Live in low 02 settings

New cards
New cards

Facultative anaerobes

Grow with and without 02 Switch between using 02 and fermentation

New cards
New cards

Anaerobes

Do not use o2 in their metabolic processes

New cards
New cards

Aerotolerant anaerobes

Tolerate o2 but don’t use it Have way to deactivate ROS Detoxify the reactive oxygen species won’t use the oxygen

New cards
New cards

Obligate anaerobes

Do not use 02 in their metabolism Can’t eliminate ROS Tend to die in aerobic environments

New cards
New cards

Bordetella pertusis (whooping cough)

Obligate aerobe

New cards
New cards

Mycobacterium tuberculosis

Facultative anaerobe

New cards
New cards

Mycoplasma pneumoniae

Obligate aerobe

New cards
New cards

Staphylococcus aureus (Staph infection)

Facultative anaerobe

New cards
New cards

Propionibacterium acnes

Aerotolerant anearobe

New cards
New cards

Helicobacter pylori (ulcers)

Microaerophile

New cards
New cards

Borrelia burgdorferi (Lyme disease)

Microaerophile

New cards
New cards

Treponema pallidum (syphillis)

Microaerophile

New cards
New cards

yersinia pestis (plague)

Facultative anaerobe

New cards
New cards

Clostridium difficile

Obligate anaerobe

New cards
New cards

Salmonella species

Facultative anaerobe

New cards
New cards

90% of cell dry weight

Carbon, hydrogen, nongaseous oxygen and nitrogen

New cards
New cards

Other elements of essential nutrients

Sulfur, phosphorus, potassium, sodium, calcium, magnesium, chlorine; various metal ions (copper, zinc, iron)

New cards
New cards

Essential nutrients

Required to build new cells Found in the organic and inorganic compounds of a microbe’s environment

New cards
New cards

Macronutrients

Needed in large amounts (carbon)

New cards
New cards

Micronutrients

Needed in very small amounts (iron)

New cards
New cards

Heterotrophs

Require an external source of organic carbon ( sugar lipids, proteins)

New cards
New cards

Autotrophs

Do not require an external source of organic carbon- used carbon fixation to convert inorganic carbon into organic carbon

New cards
New cards

Growth factors

The necessary substances that a cell can’t make on it’s own

New cards
New cards

fastidious

having complicated nutritional requirements; especially growing only in special artificial cultures- need multiple growth factors

New cards
New cards

Growing fastidious microbes in labs

Amino acids, vitamins, and/or nitrogenous bases must be supplied in the growth medium

New cards
New cards

Phototrophs

Organisms that use light energy

New cards
New cards

Chemotrophs

Organisms that break down chemical compounds for energy

New cards
New cards

Photoautotrophs

Inorganic (usually CO2), Cyanobacteria found in freshwater environments

New cards
New cards

Photoheterotroph

Organic; heliobacillus mobilis found in rice paddy fields

New cards
New cards

Chemoautotroph

Inorganic (usually CO2); Thiobacillus denitrificans found in soil, mud, and freshwater and marine sediments

New cards