Lecture #5 - The Effect of Physical & Chemical Conditions on Microbial Growth Flashcards

Question

Mesophiles found in:

Answer 1

• Warm-blooded animals (include us, cows, goats etc.) • Terrestrial and aquatic environments - diff bodies of water • Temperate and tropical latitudes - warm-temp within this range most of the time

Answer 2

* Extremophiles * Psychrophiles * Psychrotolerant

Answer 3

• Organisms that grow under very hot or very cold conditions OR like LOW pH/HIGH pH/HIGH [salt] etc.

Answer 4

• Organisms with cold temperature optima (<20oC) • Inhabit permanently cold environments - Deep ocean, Arctic and Antarctic environments

Answer 5

* Organisms that can grow at 0oC but have optima of 20oC to 40oC * More widely distributed in nature than true psychrophiles can tolerate - don't have a desire in either temps (can tolerate either), but prefer temps that are warmer (mediocre like we like)

Answer 6

1. MORE UNsaturated PL's tails - so VdW's are less likely to form even though they want 2. Produce ANTI-FREEZE compounds - prevent water from solidifying - mem. stay in fluid state that's req & inside the cell as well

Answer 7

(present inside cell that allow for support) - if they don't have those molecular dets, there will def be problems with their ability to thrive • Production of enzymes that function optimally in the cold - if it can't handle these cold conditions then its out of luck • Modified cytoplasmic membranes - High unsaturated fatty acid content

Answer 8

makes packaging challenging - positioning within the mem. (could also be both tails)

Answer 9

now as the bonds want to form & mem. wants to solidify, you incorporate unsaturation & so bond still doesn't form

Answer 10

move them further apart & the bonds won't form | - idea is to maintain a mem. that's semi-fluid consistency

Answer 11

only prokaryotic life forms exist | NO EUK CAN think: car that is complicated & has more that can go wrong & less you'll be able to tolerate

Answer 12

• Chemoorganotrophic (use organic molecules) and chemolithotrophic (use inorganic molecules) species are present • No phototrophy above approx. 70oC - chemotrophy - phototrophic organisms have a bunch of intracellular mem. content that allows for the absorption of light energy & conversion into chemical energy (therefore, that machinery can't handle high temp, it loses its structural integrity & ability to function & that machinery to be able to convert light energy into chemical energy also has temp restrictions, even if we're talking about a photosynthetic prok (cyanobacterium) • High prokaryotic diversity - even at excessively high temps - therefore high density translates into fact that living in these high temps, some organisms use nitrogen metabolism, others use sulfur metabolism, diverse in terms of where they live & enzymes & wastes they produce etc. that translate into what these organisms will look like when they're growing - Both Archaea and Bacteria are represented (proks, but at extreme temps its mostly archaea)

Answer 13

organisms with growth temperature optima between 45oC and 80oC (more mediocre than hyperthermophiles) • Terrestrial hot springs, very active compost --> nutrient rich, therefore more metabolism, more to eat, means more diversity which means more metabolic activity, which produces heat as a waste product - fact its so metabolically rich due to all the nutrients, that'll produce a ton of heat selectively for organisms that like higher temp

Answer 14

organisms with optima greater than 80oC • Inhabit hot environments, including boiling hot springs and seafloor hydrothermal vents that can experience temperatures in excess of 100oC (breaking H-bonds holding molecules together & you get phase change to gaseous state - water remains liquid - imp. b/c water is a polar solvent & so it must be liquid for cell activity) • Current temperature maximum record is held by an archaeon, Methanopyrus kandleri, which can grow at 122oC - wouldn't be destroyed by an autoclave

Answer 15

breaking H-bonds holding molecules together & you get phase change to gaseous state - water remains liquid - imp. b/c water is a polar solvent & so it must be liquid for cell activity

Answer 16

used to sterilize material combines temp & pressure so water remains as steam @ 121 degrees celsius (necessary to achieve sterilization) destruction of all life, viruses & ENDOSPORES (can tolerate envir extremes)

Answer 17

destruction of all life, viruses & ENDOSPORES (can tolerate envir extremes)

Answer 18

NO - autoclave is 121 degrees celsius | - but it won't grow in many places

Answer 19

check for antibiotics in a place you know that temp & envir is v. unique, microbial diversity will be characteristic of that place, so what might this organism be producing that might be of use to us

Answer 20

b/c of this pressurization of this water so far down the surface of earth, it makes a situation where even if water tends to boil under atmospheric pressure, under this high level of pressure the water molecules are forced into close proximity to 1 another - even though heat will make them wanna move more, they're so close to each other that they form a H-bond so it stays in a liq state as a result

Answer 21

• Specific modifications provide thermal stability to enzymes and proteins • Modifications in cytoplasmic membranes to ensure heat stability - Bacteria have lipids rich in saturated fatty acids - Archaea have lipid monolayer rather than bilayer

Answer 22

Bacteria have lipids rich in saturated fatty acids

Answer 23

Archaea have lipid monolayer rather than bilayer (space = no VdWs there)

Answer 24

enzymes widely used in industrial microbiology • Example: Taq polymerase used to automate the repetitive steps in the polymerase chain reaction (PCR) technique • Hydrolytic enzymes including proteases, cellulases and lipases

Answer 25

used to automate the repetitive steps in the polymerase chain reaction (PCR) technique - b/c enzyme required to separate strands & applies heat for destruction • Hydrolytic enzymes including proteases, cellulases and lipases - needed for normal destruction of organic material

Answer 26

``` more stable (b/c functioning under excessive characteristics) and tend to have higher activity than their mesophilic counterparts *rxn rates can be increased by increased temperature ```

Answer 27

increased temperature

Answer 28

it would be disruptive & if you turn up the temp, you turn up all the rxns - whereas an enzyme will more specifically be ablel to turn up some & not others

Answer 29

* New species of thermophiles and hyperthermophiles are still being discovered * Laboratory experiments with biomolecules suggest 140–150°C (may be able to isolate an organism - imp. b/c you might run into lifeforms at high temps like hot springs, allows us to understand more about complexes that these organisms are able to generate & more about if theres antibiotics there that would've been ignored)

Answer 30

bacteria start at around 60 degrees celsius & cap at around 100 degrees celsius archaea start at around 80 degrees celsius & cap at around 125 degrees celsius (therefore higher ceiling & floor --> higher temp limits)

Answer 31

ancient microbes

Answer 32

* Hyperthermophilic Archaea and Bacteria are found on the deepest, shortest branches of the phylogenetic tree * The oxidation of H2 is common to many hyperthermophiles * May have been the first energy-yielding metabolism

Answer 33

Thermophilic Phototrophy - until 73 degrees celsius Thermophilic Chemoorganotrophy (use organic chemicals) - until 110 degrees celsius Thermophilic Chemolithotrophy (use inorganic chemicals) - until 122 degrees celsius all cross over until 73 degrees celsius at 95 degrees celsius - elemental sulfur & reduced iron is used for nutrients H2 - energy poor but abundant - used to support organisms like prok. that have v. low energy demands (considered on early earth as a potential nutrient source for the earliest of life forms)

Answer 34

1. Small - simple prok. organisms | 2. Eat more (even though H2 is poor in terms of energy, but eat more)

Answer 35

microbial growth

Answer 36

low or high pH

Answer 37

neutrophiles * - cause problems inside our body - have medical relevance

Answer 38

• Organisms that grow best at low pH (<6) | can vary pH - etc. 5.5, 5, 2 etc.

Answer 39

• Organisms that grow best at high pH (>9) | can vary pH - 10.5, 10, 9.5 etc.

Answer 40

pH = 7.35 ish (with exceptions)

Answer 41

protein/lipid structure etc.

Answer 42

pH ~ 2.2 COOH -> COO- COOH cannot form ionic bonds COO- can form ionic bonds (to hold a protein together) pH ~9.6 NH3+ -> NH2 NH3+ can form ionic bonds (to hold a protein in a certain shape) NH2 cannot form ionic bonds

Answer 43

chemical structure, proteins & other molecules & those dramatic effects on chemical structure translate into ability/inability to form a bond - if you needed to form a bond & lost an ability b/c of pH change, these are substantial effects

Answer 44

charge changes, & changes are critical in formation of ionic bonds, which will then be associated with shape & consequently the function of the protein (ex ability to recognize substrate if its an enzyme, ability to transport nutrient if its an integral mem. protein etc.)

Answer 45

- stomach pH ~1-3 based on if food is present b/c it serves as a buffer gastric juice has hydrochloric acid which is a pH of 1 - serves to protect you against incoming microbes present on food - vaginal pH ~4.5 - protects against sexually transmitted infection

Answer 46

* The cytoplasmic membrane MAINTAINS ITS INTEGRITY at the growth pH * The internal pH of a cell must stay relatively close to neutral even though the external pH is highly acidic or basic (1. mem. with structural integrity, 2. mem. with functional capacity - mem. must still be able to bring nutrients in & out & stabilize at these pH conditions (no repulsion), integral mem. proteins still need to be able to insert into the mem.)

Answer 47

buffers to maintain constant pH | - neutralizes acid or base produced as metabolic waste!

Answer 48

Some bacteria produce acids • Acetic, lactic, sulfuric acid --> decreases the pH Some bacteria grow on amino acids • Releases ammonia --> increases the pH

Answer 49

Acetic, lactic, sulfuric acid --> decreases the pH | buffer & GM can offset this

Answer 50

Releases ammonia --> increases the pH | buffer & GM can offset this

Answer 51

protons - rush in & acidify cytoplasm (bad), so must have way to keep inside (cytoplasm) neutral regardless of outside!

Answer 52

low - pH ~ acidic <6

Answer 53

Doesn't matter what external envir. is gonna be, inside cytoplasm it has to stay neutral despite what they can tolerate outside - means they have to have elaborate mech's to be able to pump out acid if they're acidophilic, b/c acidophilic organisms are gonna have a lot of H+ outside - it'll have a tendency for the protons to move in & acidify the cytoplasm & that's where they must have some mode in place to protect against that to make sure that it doesn't happen

Answer 54

- lot of lactose naturally present - microbes can do lactic acid fermentation, as they ferment lactose in milk, they start to build up acid & that acid will start to restrict their own growth (AKA own poop is poisonous to them & serves to arrest their activity) growth media can have similar situation take place - our responsibility as experimenters to add a buffer that'll mop up that acid being produced, so it doesn't serve to inhibit the success or growth of organism

Answer 55

organism can use this as nutrient source b/c it has C as part of its backbone - BUT in order to feed this AA into something like cellular respiration, you have to do a deamination rxn (cleave off NH3 group), C framework is left behind & can be catabolized to make ATP - amino group (NH3) can come together with a H+ & form NH4+ - if it's come together with a protein, what has it done to surrounding medium? - less acidic (more basic) - b/c buffered protons that's been around

Answer 56

water availability; expressed in physical terms (HOW MUCH WATER IS AVAIL. FOR CELL TO USE) • Defined as the ratio of vapor pressure of air in equilibrium with a substance or solution to the vapor pressure of pure water • Reflects the amount of water that is interacting with ions and polar compounds in solution cell is 60-80% water

Answer 57

indicates it has partial + & partial - that exist throughout molecule to provide favourable int. with things like ions & polar monomeric molecules like AA, fructose, galatose, lactose - so this molecule can provide solubility to that, keep it in solution so you don't have chunks, but instead have flow

Answer 58

HIGHER • Water will want to move into the cell creating turgor pressure (from [low] --> [high]) SWELLS - if its a bacterium, they have a cell wall that can provide protection against rupture, but when it swells you have opp. to burst depending on how much water rushes in

Answer 59

OUT - cell SHRIVELS/DEHYDRATES as a conseq. of water loss • Cells can sometimes have mechanisms in place to prevent this - more adaption they have, more likely they'll be to survive a partic. set of circumstances which will be beneficial to the cell

Answer 60

- volume is a characteristic of [ ] & since the cell will have a lot of solutes in such a small amount of volume, the [ ] in inevitably high - whereby, the ECF is gonna have solutes, but volume will be low by comparison

Answer 61

0.9 ISOTONIC

Answer 62

grow best at reduced water potential; have a specific requirement for NaCl • Many marine microbes - live in salt H20 LOVING OF SALT - loss a lot of water b/c of high concentrated envir. & that's how they thrive best

Answer 63

grow best at reduced water potential; have a specific requirement for NaCl • Many marine microbes - live in salt H20 LOVING OF SALT - loss of water b/c of high concentrated envir & that's how they thrive best

Answer 64

Require high levels of NaCl for growth - has compacity to hold its water under these conditions - has to have mech. in place to prevent dehydration • 15–30% (can handle 3x NaCl compared to us (0.9%) • Ex) Microbes from Great Salt lake or the Dead Sea

Answer 65

can tolerate some reduction in water activity of environment but generally grow best at lower solute concentrations • Ex) Staphylococcus aureus • Lives on human skin • Grows best at low NaCl (optimum is low) • But can tolerate up to 17.5% (what a normal organism would consider isotonic)

Answer 66

NO - have to be cognizant of temp, pH, nutrition have to be met in order to achieve this

Answer 67

• Organisms that grow with high sugar as solute

Answer 68

• Organisms able to grow in very dry environments (v. lil water avail)

Answer 69

• Honey, jams and jellies do not have many organisms growing in them - don't need to be refrigerated - v. hypertonic envir., water lost from those organisms to the surroundings & won't be able to continue • Beef jerky and salted cod - not refrigerated b/c its so concentrated, that any contaminants that made their way in are not gonna be able to cause spoilage b/c its so salty that they'll immediately dehydrate

Answer 70

acid producing microorganisms

Answer 71

* Used for sauerkraut and pickle fermentation * Combination of high salt and low pH prevents the growth of most pathogens in the completed product AKA organisms tha can handle really concentrated EC envir. are often also associated with acid production (i.e. tolerate high salts & also metabolically produce acid as a waste product) - then these organisms will decrease pH of surroundings *- outcome: organism is gonna be collectively controlling for growth & pathogen (decrease pH will occur & pathogens that cause disease don't grow)

Answer 72

outcome: organism is gonna be collectively controlling for growth & pathogen (decrease pH will occur & pathogens that cause disease don't grow)

Answer 73

Extracellular conditions (AKA environment)

Answer 74

anything that creates an internal envir. that's more isotonic - but don't wanna introduce another prob. for yourself • PUMPING INORGANIC IONS from environment into cell - which is making cytoplasm more isotonic relative to surroundings - making an effort to hold water inside the cell as a result of this beh. OR • SYNTHESIZING OR CONCENTRATING ORGANIC SOLUTES - COMPATIBLE SOLUTE: compounds used by cell to counteract low water activity in surrounding environment - which will not upset or affect function of the cell - will not screw up concentration gradient that might be critical for something else - imp. that whatever is being brought in to offset loss of water, will not upset something else

Answer 75

compounds used by cell to counteract low water activity in surrounding environment

Answer 76

oxic zone - coloured production in medium indicates the presence of O2 thioglycolate broth - reducing medium that converts O2 into a reduced end product anoxic zone - coloured production indicates the absence of O2

Answer 77

coloured production in medium indicates the presence of O2

Answer 78

reducing medium that converts O2 into a reduced end product

Answer 79

coloured production indicates the absence of O2

Answer 80

- poisoned by O2 (all at bottom) | - fermentation or anaerobic respiration to produce ATP

Answer 81

- not poisoned by O2 (all at top) | - aerobic respiration to produce ATP

Answer 82

- not poisoned by O2 (no desire to go where O2 is or isn't --> equally distributed) - they do not have ETC (meaning they cannot use O2, therefore any respiration is impossible) - so they can only use fermentation to produce ATP

Answer 83

- poisoned by O2 BUT needs O2 for cell respiration (right below oxic zone) use O2 for cell respiration, but O2 is NOT in high enough [ ] that it'll ever accumulate to create the poisonous affects that the cell would otherwise experience so that's why its there - as soon as O2 comes in through ETC (located in PM of prok cells), it's used & converted to H20

Answer 84

they'd die b/c O2 [ ] inside the cell would accumulate higher & cause poisonous affect & cell wouldn't be capable of survival under those conditions

Answer 85

prefers oxic zone - CAN SWITCH - not poisoned by O2 - use cell respiration or fermentation to produce ATP - prefer O2 b/c ATP yield is way higher

Answer 86

require oxygen to live

Answer 87

do not require oxygen and may even be killed by exposure - poisoned by O2 presence, therefore stay far away from it

Answer 88

can live with or without oxygen, they use oxygen when it is available - not killed by O2, but prefer to use O2 if present b/c it allows for maximization of energy production for each substrate used (more energy yield) within the catabolic pathway

Answer 89

can tolerate oxygen and grow in its presence even though they cannot use it (b/c they lack an ETC) - therefore, solely restricted to fermentation as a means of satisfying their energy requirement - no poisonous effects with O2

Answer 90

can use oxygen only when it is present at levels reduced from that in air - but poisoned by it as well (need it, but can't handle it so they satisfy themselves in low concentration) - live at a part of the tube where O2 is avail., but O2 is minimized, therefore satisfies just their needs without creating a toxic effect

Answer 91

* Complex medium (not defined) that separates microbes based on oxygen requirements * Thioglycolate reacts with oxygen creating an anaerobic environment

Answer 92

* Oxygen can penetrate only the top of the tube * Contains an oxygen responsive dye that turns pink in the presence of oxygen and colorless when the oxygen is low or absent thioglycolate - chemical that'll eliminate O2 & force the tube to become anaerobic, especially within certain regions

Answer 93

oxic zone - at top area of water b/c non-polar attribute of O2 gas only allows it to reach in equil. here anoxic zone - as you start to go lower down within water column - its anoxic b/c O2 polarity makes it not interact favourably with the polarity of the water - b/c its anoxic, any organism that'll be in this region will be microaerophilic (gets best of both worlds to be able to cater to its own needs)

Answer 94

grows only in the oxic zone at the top of the tube

Answer 95

grows only in the anoxic zone at the bottom of the tube

Answer 96

grows throughout the tube • Better growth occurs in the oxic zone, where it can generate energy by aerobic respiration

Answer 97

grows in a narrow band between the oxic and anoxic zones • Needs O2 for aerobic respiration • Killed by atmospheric O2 levels

Answer 98

grows well throughout the tube • Doesn’t use O2 • Not harmed by O2

Answer 99

Special techniques are needed to grow anaerobic microbes - b/c if an infection is anaerobic it's understood that collectively that sample & exposing it to O2 is gonna kill your organism - when you get it to a lab later, you anticipate the organism isn't gonna grow b/c its been killed off by the O2 concentration - therefore, have to be aware of this & collect sample properly or else it won't make it to lab for further study, diagnosis etc.

Answer 100

Reducing agents may be added to culture media to reduce oxygen - take O2 & add e-'s (e- donor, therefore reducing agent) to it & form H20 for ex which is benign - gets rid of poisonous O2 this way & water is no problem --> method of O2 removal to support anaerobes • Ex's: Thioglycolate (create anaerobic envir. in test tube of broth), cysteine (AA that can donate e's from its R group), H2S and other sulfur containing compounds Removal of air, and replacement with an inert gas - remove ordinary atmospheric components from the top of this container & replace with inert gas to occupy space but not create unfav. activity) • Ex) nitrogen or argon OR anaerobic chamber - hands go in to allow you to work - envir. present within chamber has been created such that theirs no O2 so it'll continually support an organism that can't handle O2 well

Answer 101

an oxidizing capacity

Answer 102

* Superoxide anion - HIGHLEY REACTIVE * Hydrogen peroxide - FORMS HIGHLY REACTIVE MOLECULES (indirect) * Hydroxyl radical - HIGHLEY REACTIVE worried about these called ROS - reactive oxygen species

Answer 103

reactive oxygen species

Answer 104

O2 + e- --> O2- - O2 present in atmosphere has capacity to come together with a free e- - O2- unpaired e- - tendency to form this reactive O2 species is problematic b/c it has an unpaired e- - therefore, desperate to pair it off (think: desperate to find relationship - nothing good will happen) - will interact with DNA, protein, mem., & causes mutation (changes to chemical structure that can lead to changes in the function) - dangerous b/c of high reactivity - desperation to pair off the e-

Answer 105

O2- + e- + 2H+ --> H2O2 - superoxide radical chooses to pair its e- with another e- avail. in a form of H atom & forms H202 think: satisfying 1 alarm, but fix with another alarm inducing molecule

Answer 106

H202 + e- + H+ --> H20 + OH H2O2 is effective of healing wound b/c it pairs with e-'s in form of H atoms & forms hydroxyl radicals (like superoxides b/c desperate to engage or beh. with other species present)

Answer 107

water take unpaired e- of hydroxyl & combine with H atom which contains an e- & form water (benign)

Answer 108

* Catalase * Peroxidase * Superoxide dismutase * Superoxide reductase enzymes that have opp. to provide protection to organisms that can tolerate O2 (should have some combo to ensure survival is possible)

Answer 109

They don’t have a mechanism to combat OXIDATIVE STRESS - so they stay away from O2 to survive & molecules don't suffer mutation & destructive effects from these species & able to produce less amounts of energy then if they could use O2 but at least they'll be alive think: someone putting book in front of fist so you're not able to get punched & have damage to organs b/c something else bore the brunt of the punch What we can do inside our cell when we have the potential to suffer damage from O2: - we can grab NADH (reduced) (book) - now instead of O2 causing damage to DNA through its radical formation to proteins etc. - you form H20 & NAD+ - protect abdominal organs by consuming NADH that took punch instead - protected DNA & other critical cell structures by using an NADH equivalent in order to be able to undergo oxidation in expense of O2 reactivity O2 + NADH --> NAD+ + H20

Answer 110

- NADH turns into ATP in ETC by giving off its high energy e-'s - therefore, in this case you're using what would've been ATP & instead using it to eliminate O2 that would've been causing problems inside cell, consuming it but protecting vital components in cell - imp. to us

Answer 111

H202 + H202 --> 2H20 + 02 | - consumes 2 equivalents of H202 & produces benign things (well tolerated)

Answer 112

H202 + NADH + H+ --> 2H20 + NAD+ - takes same H202 as catalase - put book in front of molecule (NADH equivalent together with H202) - H202 is aggressively oxidizing & NADH donates its e-'s --> form H202 (benign) & NAD+ (empty e- carrier, which is now recyclable & able to be used in glycolysis, krebs & intermediate step to collect more e-'s again) - but in doing so you: THEORETICALLY CONSUME 2.5 ATP = NADH's worth in the ETC - b/c NADH can't go to ETC anymore

Answer 113

SAME - deadly reactant (H202) DIFF - put book in front of molecule (NADH equivalent together with H202)

Answer 114

O2- + 02- + 2H+ --> H202 + 02 - consumes 2 "deadly" O2 equivalents (reactants we're trying to eliminate from cell) & produces another alarm (H202) - you got rid of O2 equivalents which is good, but then you have to deal with H202...

Answer 115

402- + 4H+ --> 2H20 + 302 - take 2 equivalents of superoxide & form H202 - then you have catalase (another enzyme in combo) - takes 2 equiv. of H202 & finally are relieved (nothing bad from that rxn)

Answer 116

02- + 2H+ + rubredoxin(reduced) --> H202 + rubredoxin(oxidized) - O2 works with rubredoxin (reduced) rubredoxin (reduced) is analogous to: NADH (book) - reduced form & has opp. to donate its e-'s to O2 radical H202 - another alarm b/c it poses problem inside cell again rubredoxin (oxidized) is oxidized with its e-'s - e's are on O2

Answer 117

- encoded within the genome or present on a plasmid, chromosome, mobile element (somewhere within genetic makeup) - allows cell to tolerate O2 b/c it has the recipe to make the enzyme * - if you don't have recipe to make enzyme is when you have a problem