Microbial Growth Environments

Question 1

what are extremophiles?

Answer 1

organisms that grow under harsh conditions that would kill most other organisms

Question 2

what are common influential environmental conditions?

Answer 2

changing solute concentrations, pH, temperature, oxygen concentration, pressure

Question 3

what conditions do most microbes prefer?

Answer 3

neutral environment conditions (osmolarity, temp, pH, and pressure)

Question 4

what are the most common mechanisms used by extremophiles?

Answer 4

synthesized specialized enzymes and proteins, altering of genomic material, altering membrane composition, opening/closing channels or similar mechanism to acquire or remove substances to balance the intracellular environment

Question 5

what is the typical outcome of osmotic concentrations on most microbes?

Answer 5

depending on osmolarity, there will be an influx of water in or out of the cell, causing it to burst or to shrink

Question 6

how do microbes adapt to changes in osmotic concentration?

Answer 6

trigger channels in the membranes to ope which allows solute to leave or increase their internal osmotic concentration

Question 7

what is the typical outcome of pH changes on most microbes?

Answer 7

cytoplasmic pH becomes acidic or alkaline, causes cell death

Question 8

how do microbes adapt to pH changes?

Answer 8

utilize mechanisms that maintain a neutral pH such as exchange of protons, synthesizing special proteins, or producing waste products to balance the environmental pH

Question 9

why are microbes so sensitive to temperature change?

Answer 9

microbes cannot regulate their internal temperature and their enzymes do not function well outside of their optimal range

Question 10

how do microbes adapt to temperature changes?

Answer 10

utilize means to stabilize proteins and membranes

Question 11

what is the typical outcome of oxygen concentration changes on most microbes?

Answer 11

organisms can be strict to facultative aerobes or anaerobes
O2 is toxic to strict anaerobes, so they must find other ways to make energy. strict aerobes are not fit for oxygen poor environments, so they will die without it

Question 12

how do obligate anaerobes adapt when there is oxygen present?

Answer 12

they will sometimes associate with facultative anaerobes who will remove any oxygen from the environments
they also utilize enzymes that scavenge and neutralize reactive oxygen byproducts

Question 13

what pressure are all microbes always at?

Answer 13

1 atm

Question 14

what microbes need adaption mechanisms for pressure changes?

Answer 14

extremophiles

Question 15

what are the four main types of extremophiles?

Answer 15

halophiles, acidophilus, thermophiles, and obligate anaerobes/aerobes

Question 16

what happens when cells are in a hypotonic solution?

Answer 16

water enters the cell which causes it to swell and burst

Question 17

what happens when cells are in a hypertonic solution?

Answer 17

water leaves the cell, causing membrane shrinkage from the cell wall

Question 18

how do microbes reduce osmotic concentration of their cytoplasm in hypotonic solutions?

Answer 18

mechanosensitive channels in the plasma membrane

Question 19

what are halophiles?

Answer 19

microbes that grow optimally in the presence of NaCl or other salts at a concentration above about 0.2 M

Question 20

what makes a halophile extreme?

Answer 20

require salt concentrations between 3 and 6.2 M
their cell wall, proteins, and plasma membrane require high salt to maintain stability and activity

Question 21

what are bacteria and protists classified as in regards to pH preference?

Answer 21

neutrophiles

Question 22

what conditions do fungi prefer (pH)?

Answer 22

more acidic environments, between 4-6

Question 23

what are most archaea classified as (pH)?

Answer 23

acidophiles (pH of 0-5)

Question 24

what is the acidic tolerance response?

Answer 24

microbes pump protons out of the cell
some synthesize acid and heat shock proteins that protect main proteins

Question 25

how do many microbes change the pH of their habitats?

Answer 25

by producing acidic or basic waste products

Question 26

what are the 3 distinct cardinal growth temperatures?

Answer 26

minimal, maximal, and optimal

Question 27

what is the temperature range for psychrophiles?

Answer 27

0-20 degrees C

Question 28

what is the temperature range for psychrotrophs?

Answer 28

0-35 degrees C

Question 29

what is the temperature range of mesophiles?

Answer 29

20-45 degrees C

Question 30

what is the temperature range for thermophiles?

Answer 30

55-85 degrees C

Question 31

what is the temperature range for hyperthermophiles?

Answer 31

85-113 degrees C

Question 32

how do thermophiles adapt to high temperatures?

Answer 32

they have more chaperone proteins and H bonding in proteins they have more saturated, branched and higher MW lipids they have ether linkages in the archaeal membranes

Question 33

what are barotolerant microbes?

Answer 33

adversely affected by increased pressure, but no as severely as non tolerant organisms

Question 34

what are barophilic (peizophillic) microbes?

Answer 34

microbes that require or grow more rapidly in the presence of increased pressure can change membrane fatty acids to adapt to high pressures

Question 35

what gas has the higher impact on microbial growth? O2 or CO2?

Answer 35

O2

Question 36

what are the three categories that microbes fall into in regards to oxygen concentration?

Answer 36

those that use oxygen and detoxify it those that can neither use nor detoxify oxygen those that do not use oxygen but can detoxify it

Question 37

what is a singlet oxygen?

Answer 37

an extremely reactive molecule that can damage and destroy a cell by the oxidation of membrane lipids

Question 38

what are the other 3 toxic byproducts of microbial oxygen processing?

Answer 38

superoxide ions, hydrogen peroxide, and hydroxyl radicals

Question 39

what enzyme converts superoxide ions into hydrogen peroxide?

Answer 39

superoxide dismutase

Question 40

what enzyme converts hydrogen peroxide into water and oxygen?

Answer 40

catalase

Question 41

what are aerobes?

Answer 41

microbes that can use gaseous oxygen in their metabolism and posses the enzymes needed to process toxic oxygen products

Question 42

what are some examples of obligate aerobes?

Answer 42

most fungi, protozoa, and many bacteria such as Bacillus and mycobacterium tuberculosis

Question 43

what are microaerophiles?

Answer 43

microbes harmed by normal atmospheric concentrations of oxygen but require a small amount of it for metabolism

Question 44

what are facultative anaerobes?

Answer 44

microbes that do not require oxygen for metabolism but use it when present

Question 45

what are some example of facultative anaerobes?

Answer 45

many gram negative intestinal bacteria, staphylococci

Question 46

what is the difference between anaerobes and obligate anaerobes?

Answer 46

anaerobes lack the metabolic enzyme systems for using oxygen is respiration, but obligate anaerobes also lack the enzymes for processing toxic oxygen and die in its presence

Question 47

what are some examples of obligate anaerobes?

Answer 47

many oral bacteria, intestinal bacteria

Question 48

what are aerotolerant anaerobes?

Answer 48

microbes that do not utilize oxygen but can survive and grow to a limited extent in its presence

Question 49

why are aerotolerant anaerobes not harmed by oxygen?

Answer 49

they possess alternate mechanisms for breaking down peroxides and superoxides

Question 50

what are some examples of aerotolerant anaerobes?

Answer 50

certain lactobacilli and streptococci, clostridial species

Question 51

what are the characteristics of natural microbial growth environments?

Answer 51

complex and constantly changing expose a microorganism to overlapping gradients of nutrients and environmental factors contain both micro- and macroorganisms

Question 52

what types of envrionments do most microbes inhabit?

Answer 52

oligotrophic environments

Question 53

what are some of the ways in which microbes have evolved to respond to starvation and environmental stresses?

Answer 53

morphological changes such as endospores entering the stationary phase of growth curve using cellular components as nutrients numerous genes and proteins that help viable but not cultural state

Question 54

what is quorum sensing?

Answer 54

the bacterial cell to cell communication process

Question 55

how does quorum sensing work?

Answer 55

requires an autoinducer controls genes that direct activities that are beneficial when performed in synchrony produces small proteins that increase in level as microbes replicate and convert a microbe to a competent state DNA uptake occurs and encourages horizontal gene transfer

Question 56

what are some things that are controlled by quorum sensing?

Answer 56

bioluminescence, sporulation, competence, antibiotic formation, biofilm formation, and virulence factor secretion

Question 57

how do most microbes grow?

Answer 57

attached to surfaces, or sessile, rather than free floating

Question 58

what are free floating microbes called?

Answer 58

planktonic

Question 59

what is a biofilm?

Answer 59

attached microbes that form a complex, slime enclosed community

Question 60

where can biofilms form??

Answer 60

on any conditioned surface

Question 61

what are the five steps of biofilm formation?

Answer 61

1. reversible attachment of planktonic cells 2. first colonizers become irreversibly attached 3. growth and cell division 5. production of EPS and formation of water channels 5. attachment of secondary colonizers and dispersion of microbes to new sites

Question 62

what is heterogeneity?

Answer 62

differences in metabolic activity and locations of microbes

Question 63

how do interactions occur between organisms attached in biofilms?

Answer 63

exchanges take place metabolically through DNA uptake and communication