LEC. 4 - Metabolic Diversity of Microorganisms

Question 1

What are chemolithotrophs?

Answer 1

use inorganic compounds to get energy for their metabolic processes

Question 2

Which type of metabolism is considered to be the first form of energy conservation evolving on Earth?

Answer 2

chemolithotrophy

Question 3

How do we know that chemolithotrophy was the first form of energy conservation evolving on Earth?

Answer 3

found on base of Bacteria and Archaea phylogenetic tree

Question 4

Chemolithotrophs have the ability to act as autotrophs and can use CO2 as their carbon source. However, what are the 2 main components that they require in order for this to work?

Answer 4

1. reducing power
2. ATP

Question 5

How do chemolithotrophs create ATP and reducing power?

Answer 5

by oxidizing the following:
1. H2S
2. S0
3. H2
4. Fe2+

Question 6

What are the 4 energy sources for chemolithotrophs?

Answer 6

1. H2S
2. S0
3. H2
4. Fe2+

Question 7

What is an indicator that chemolithotrophy is one of the oldest metabolic processes?

Answer 7

1. energy source
2. the fact that it uses a carbon source (CO2)

Question 8

Along with H2 and H2S, list 2 other potential energy sources for chemolithotrophs.

Answer 8

1. Fe2+
2. NH4+

Question 9

What are hydrogen bacteria?

Answer 9

use hydrogen as an electron donor

Question 10

Bacteria and Archaea are awesome at multi-tasking. What is the other thing that they can couple the action of oxidizing H2 with?

Answer 10

reducing other electron acceptors like:
1. NO3-
2. SO42-
3. Fe3+
4. CO2

Question 11

What is aerobic H2 oxidizing bacteria?

Answer 11

uses O2 as terminal electron acceptor

Question 12

What do aerobic H2 oxidizing bacteria oxidize as the electron donor?

Answer 12

H2

Question 13

What do aerobic H2 oxidizing bacteria reduce?

Answer 13

O2 to form water

Question 14

For chemolithotrophs that use H2, what is the name of the enzyme that they developed?

Answer 14

hydrogenase

Question 15

What are the 2 different types of hydrogenases that chemolithotrophs evolved?

Answer 15

1. Cytoplasmic hydrogenase
2. Membrane-integrated hydrogenase

Question 16

How could one describe cytoplasmic hydrogenase?

Answer 16

as a soluble enzyme

Question 17

What is the name of the hydrogenase that most H2-oxidizing have?

Answer 17

membrane integrated enzyme

Question 18

There are some pretty unique organisms out there that use 2 hydrogeneses. What is an example of such an organism?

Answer 18

Ralstonia eutropha

Question 19

What is the main goal of the membrane enzyme for H2-oxidizing chemolithotrophs?

Answer 19

energy conservation

Question 20

What is the main goal of soluble enzyme for H2-oxidizing chemolithotrophs?

Answer 20

autotrophy

Question 21

If an organism has only 1 type of enzyme present, what are the 2 functions that they are now responsible for carrying out?

Answer 21

energy conservation and autotrophy

Question 22

H2 - oxidizing bacteria has the ability to act as autotrophs with the use of the Calvin cycle and can also grow as what other type of -troph?

Answer 22

chemoorganotrophs

Question 23

If chemoorganotrophs are given the decision to choose between glucose (organic source) or H2 (inorganic source), which one would they choose and why?

Answer 23

glucose because it gives them more energy

Question 24

For chemoorganotrophs, if there is glucose present will they synthesize hydrogenase and why?

Answer 24

no, energy conservation

Question 25

H2 bacteria are known to have a mixed nature. What term classifies this?

Answer 25

facultative chemolithotrophs

Question 26

In an oxic area, would H2 production be low or high?

Answer 26

low

Question 27

Why would H2 production be low in an oxic area?

Answer 27

1. no fermentation 2. rapic consumption by anaerobes

Question 28

What is the backup plan for H2 oxidizing bacteria?

Answer 28

they shift between chemoorgaotrophic and chemolithotrophic lifestyles based on the nutrients that are available to them in environment

Question 29

What do colourless sulfur bacteria use as electron donors?

Answer 29

reduced sulfur compounds

Question 30

In comparison to colorless sulfur bacteria, what type of photosynthesis do purple and green sulfur bacteria perform?

Answer 30

anoxygenic photosynthesis

Question 31

What are the 2 reduced sulfur compounds that chemolithotrophs can use?

Answer 31

1. hydrogen sulfide 2. elemental sulfur

Question 32

What is the first mode of biochemistry that chemolithotrophs who use reduced sulfur compounds as energy source have?

Answer 32

oxidation of hydrogen sulfide and/or S0 to sulfate (SO42-) through intermediary

Question 33

What is the second mode of biochemistry that chemolithotrophs who use reduced sulfur compounds as energy source have?

Answer 33

oxidation of hydrogen sulfide and/or S0 to sulfate (SO42-) without intermeddlers (Sox system of genes)

Question 34

Why does iron bacteria have to complete the oxidation of large amounts of iron?

Answer 34

because they're only able to produce small amounts in an acidic environment

Question 35

What are the 3 steps of acidification, the very process that is happening because of iron oxidation?

Answer 35

1. spontaneously produced ferric iron forms insoluble ferric OH- 2. precipitates are formed in an aquatic environment 3. reaction lowers pH

Question 36

Why did iron bacteria evolve to be acidophillic?

Answer 36

bc of reaction of acidification bc of iron oxidation

Question 37

What are 2 of the best known iron bacteria?

Answer 37

1. Acidithiobacillus ferrooxidans 2. Leptospirillum ferrooxidans

Question 38

What is the electron donor for Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans?

Answer 38

Fe2+

Question 39

Why type of an environment are Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans most common in?

Answer 39

acid polluted

Question 40

What is ferroplasma?

Answer 40

- archaea - acidophillic iron oxidizer

Question 41

What is the only form of iron that microorganisms can use as an energy source?

Answer 41

Fe2+ ion

Question 42

At a neutral pH, Fe2+ will spontaneously become?

Answer 42

Fe3+

Question 43

Why must iron bacteria develop an oxidation system that is fast?

Answer 43

bc it can change to Fe3+ if it comes into contact with air, and thus, not usable

Question 44

What are 3 examples of bacteria that are able to oxidize Fe3+ rapidly before it gets exposed to oxygen?

Answer 44

1. Gallionella ferruginea 2. Sphaerotilus natans 3. Leptothrix discophora

Question 45

What is nitrification?

Answer 45

chemolithotrophic nitrifying bacteria aerobically oxidizes NH3 and NO2-

Question 46

If ammonia were to be present in an anoxic environment, which type of bacteria would be able to oxidize ammonia?

Answer 46

anammox

Question 47

How could one describe the areas that nitrifying and anammox bacteria are widely distributed in?

Answer 47

wet and moist

Question 48

Which 2 organisms are responsible for oxidizing ammonia to nitrite in aerobic conditions?

Answer 48

AOB (ammonia oxidizing bacteria) and AOA (ammonia oxidizing archaea)

Question 49

Which group of bacteria is responsible for completing the full process of nitrification?

Answer 49

NOB (nitrite oxidizing bacteria)

Question 50

What does NOB (nitrite oxidizing bacteria) do?

Answer 50

oxidize nitrite to nitrate (NO3-)

Question 51

Which cycle do both NOB and AOB use to fix CO2?

Answer 51

calvin

Question 52

Why do NOB and AOB run reverse electron flow to generate NADH?

Answer 52

high energy requirements

Question 53

How does NOB use chemoorganotrophy?

Answer 53

growth on glucose or organic substrates

Question 54

Does AOB have alternate metabolism plan?

Answer 54

no, they are chemolithotrophs

Question 55

What is the name of the key plant nutrient that NOB and AOB are responsible for producing through a convertion process?

Answer 55

nitrate

Question 56

Why are nitrifiers (NOB and AOB) important for sewage and wastewater treatments?

Answer 56

1. remove toxic amines and ammonia 2. release less toxic nitrogen compounds

Question 57

How are nitrifiers significant to lakes?

Answer 57

1. decomposing organic matter in sediments produces ammonia 2. nitrifiers oxidize ammonia to generate nitrite 3. NOB convert nitrite to nitrate 4. algae and cyanobacteria need nitrate to grow

Question 58

What is anammox (anaerobic ammonia oxidation)?

Answer 58

ammonia oxidation in anoxic environment

Question 59

What performs anaerobic ammonia oxidation?

Answer 59

anaerobic bacteri

Question 60

in an anammox reaction, what is the electron donor and what is the electron acceptor and what is produced?

Answer 60

donor: ammonia acceptor: nitrite produces N2 gas

Question 61

What is a major anammox organism?

Answer 61

Brocadia anammoxidans

Question 62

Describe Brocadia anammoxidans.

Answer 62

- lack peptidoglycan - cytoplasm has membrane-enclosed compartments

Question 63

In Brocadia anammoxidans, what are the membrane enclosed compartments called?

Answer 63

anammoxosome

Question 64

How are the lipids that build anammoxosome different and not typical bacterial lipids?

Answer 64

have glycerol and cyclobutene (C4) ring attached to glycerol with ester and ether bonds

Question 65

What are the dense lipids present inside anammoxosome called?

Answer 65

ladderane lipids

Question 66

Significance of Anammox: What is the source of nitrite for anammox?

Answer 66

aerobic AOA and AOB

Question 67

How is anammox crucial for wastewater treatment?

Answer 67

it removes ammonia and nitrite to produce N2 and H2O

Question 68

What is fermentation?

Answer 68

microbes degrading organic compounds in metabolic process bc no other stuff is available

Question 69

If fermentative organisms do not run the electron transport chain, then what do they do?

Answer 69

create ATP and NADH through Substrate Level Phosphorylation

Question 70

Briefly, how does fermentation work?

Answer 70

- substrate is electron donor and acceptor - SLP makes ATP

Question 71

microbes fermenting sugars to make acids/alcohols as primary products

Answer 71

primary fermenters

Question 72

microbes using products from primary fermenters to make gasses for other microbes (methanogens, sulfidogens, acetogens)

Answer 72

secondary fermenters

Question 73

What is the number one product that is excreted from fermentation?

Answer 73

H2

Question 74

What are some other end products of fermentation?

Answer 74

alcohols and acids

Question 75

What are fermentations classified by?

Answer 75

1. substrate fermented 2. products formed

Question 76

What are some of the broad categories of fermentation?

Answer 76

- alcoholic fermentation - lactic acid fermentation - mixid acid fermentation - butyric acid - acetogenic fermentation

Question 77

In homolactic fermentation, what is the product?

Answer 77

lactate

Question 78

In homolactic fermentation, some organisms have ethanol dehydrogenase and they reduce pyruvate to...

Answer 78

ethanol

Question 79

Because there is no aldolase that is present in heterofermentative, how will the process change?

Answer 79

going from 6C to 5C

Question 80

Which type of bacteria is responsible for eating and transforming lactose, fat and protein in milk?

Answer 80

lactic acid

Question 81

What is the importance of homofermentation to cheese?

Answer 81

mild flavour + acidity of cheddar

Question 82

What is the importance of heterofermentation to cheese?

Answer 82

complex "fruity" flavour and holes of swiss

Question 83

What performs butyric acid fermentation?

Answer 83

clostridum

Question 84

What is the gram + organism content in butyric acid fermentation leading it be what?

Answer 84

low and aerotolerant

Question 85

What are the early fermentation products in butyric acid fermentation and how do they affect the pH?

Answer 85

- acetate and butyrate - lowers pH

Question 86

What is the name of the process that has no cytochromes?

Answer 86

butyric acid fermentation

Question 87

How does low pH in butyric acid fermentation affect the genes that are produced?

Answer 87

- different sets of genes will redirect process - microbe consumes butyrate and acetate to make butanol and acetone

Question 88

In the stickland reaction fermentation, what is the electron donor and acceptor?

Answer 88

alanine - donor acceptor - glycine

Question 89

What are the substrates in the stickland reaction fermentation?

Answer 89

- 2 amino acids - ADP - Pi

Question 90

What are the products in the stickland reaction fermentation?

Answer 90

- acetate - ammonium - CO2 - 3 ATP

Question 91

Why is the strickland reaction important for our bodies?

Answer 91

prevents cavities

Question 92

How does strickland reaction work in our mouths?

Answer 92

- comes between free roaming proline and amino acids (made by plaque) - product: δ-NH2 valeric acid - degrades to ammonia - ammonia removes H+, lowers acidity

Question 93

What part of our mouth is proline found in?

Answer 93

saliva

Question 94

What is the name of a common plaque bacteria?

Answer 94

Peptostreptococci

Question 95

What does Peptostreptococci do in our mouth?

Answer 95

complete glucose fermentation, producing free amino acids