ENV 4.2 - Microbes serving the Green transition

Question 1

What are the main differences of aerobic/anaerobic growth?

Answer 1

STIKORD: Aerobic: Oxygen som elektronacceptor, mere effektiv
Anaerobic: Alternative elektronacceptorer; NO3-, CO2

Aerobic: Oxygen is required for their metabolism. Oxygen serves as the final electron acceptor in the electron transport chain, facilitating the production of ATP through aerobic respiration

Anaerobic: Oxygen is not required for growth. Alternative electron acceptors such as nitrate, sulfate, CO2, for their metabolism.

Aerobic metabolism generates more energy (ATP) per molecule of substrate compared to anaerobic metabolism. => due to higher efficiency of aerobic respiration in extracting energy from substrates.

Question 2

Describe the four different steps of anaerobic degradation of complex organic matter

Answer 2

hydrolysis, acidogenesis, acetogenesis, and methanogenesis.

1. Hydrolysis; Organic matter is broken down into its smaller components (carbohydrates, Proteins, Lipids). Enzymatic process, where H 2 O molecule is splitting the organic macromolecule in smaller units
2. acidogenesis: formation of acids by acidogenic microorganisms absorbing the products of hydrolysis through their cell membranes. Intracellular process. At the same time H 2 is produced. Follows branched metabolism, determined by the H 2 level
3. acetogenesis: Processing the accumulated volatile fatty acids, ethanol, etc.to acetate and H2.
   Intracellular process, At the same time H 2 is produced. Follows linear metabolism, i.e. does not occur unless the H 2 is low enough
4. methanogenesis. Methane is produced from acetate.
   Acetate=> CO2+CH4
   4H2+CO2=>CH4+2H2O

Question 3

Difference of branched and linear metabolism

Answer 3

linear metabolism proceeds sequentially from a starting substrate to an end product with minimal branching, while branched metabolism involves pathways that diverge into multiple interconnected routes, allowing for the production of multiple end products from different intermediates

Question 4

Describe what synergism between microorganisms is

Answer 4

Synergism between microorganisms is when they cooperate to achieve a result that is greater than the sum of their individual efforts. It involves collaboration in processes like metabolism, nutrient exchange, biofilm formation, cross-feeding, and symbiotic relationships.

Question 5

Determine possible conversion products out from available substrate/nutrients and microorganisms

Question 6

Which substrates can be used by archaea?

Answer 6

Acetate: Methanosaeta use acetate as electron donor.
Methanosaeta species are acetoclastic methanogens, meaning they have the unique ability to directly convert acetate into methane (CH4) and carbon dioxide (CO2) through a process known as acetoclastic methanogenesis. Acetate serves as both a carbon and energy source for Methanosaeta.

H2, acetate and methanol/methylamine: Metanosarcina use H2, acetate and methanol/methylamine.
Members of the genus Metanosarcina are versatile methanogens capable of utilizing a variety of substrates for methanogenesis. Metanosarcina species can utilize hydrogen gas (H2) as an electron donor and acetate as a carbon and energy source. Additionally, they have the metabolic flexibility to utilize other substrates such as methanol and methylamines (e.g., methylamine, dimethylamine, trimethylamine) for methanogenesis. This versatility allows Metanosarcina to thrive in diverse environments where these substrates are available

Question 7

How can microorganisms get their energy?

Answer 7

Microorganisms can derive energy from carbohydrates, alcohols, and amino acids. Most microorganisms will metabolize simple sugars such as glucose. Others can metabolize more complex carbohydrates, such as starch or cellulose, or glycogen found in muscle foods. Some microorganisms can use fats as an energy source

Either energy from chemical sources (chemotrophy) or light (phototrophy)

Microbes catalyze redox reaction to release energy which is captured in biomolecules (ATP)

Question 8

Does energy production requires a presence of electron donors?

Answer 8

Yes, the electron donors deliver electrons to the electron transport chain. If these are not delivered then the generation of ATP can not happen

Question 9

What describes whether a reaction can provide energy for the microorganisms?

Answer 9

It depends on its gibbs free energy change. If negative energy is released and can be used for energy production by microorganisms.

It depends on the redox potential. If it is positive then gibbs free energy echange is negative and the reaction will release energy,

Question 10

What is denitrification?

Answer 10

the microbial process of reducing nitrate and nitrite to gaseous forms of nitrogen, principally nitrous oxide (N2O) and nitrogen (N2).’

Anaerob
Chemolithoheterotrophs:
Cannot fix carbon and need therefore a carbon source = (Hetero)

Question 11

What is Chemical Oxygen demand?

Answer 11

COD: Measure of the strength‐/concentration of
wastewater. Describes the amount of O2 to fully
oxidize the organic matter.
It is the amount of oxygen consumed during the oxidation of oxidizable organic matter in the presence of strong oxidizing agent.
High COD levels indicate a higher concentration of organic pollutants, such as carbohydrates, proteins, fats, and other organic compounds, which may require more oxygen for their oxidation

Question 12

Is lignin biodegradable? and which 3 macromolecules does the cell wall consists of?

Answer 12

STIKORD: Ligning is; strcutre of the cell wall, degrades very slowly, organic polymer of aromatic compounds

The cell walls consists of 3 macromolecules: cellulose, hemicellulose and lignin.

a complex organic polymer consisting of a variety of phenolic compounds
Lignin: Wire fench that give structure to the wall. complex, crosslinked and 3D aromatic polymers.
Lignin degrade very slowly by microbes due to the complex structure. The degradtion happens under anaerobe conditions. And can therefore not be as an Carbon- and energy source

Cellulose: unbranched polymer of glucose

Hemi-cellulose: branched polymer of various sugar units

Question 13

What is the characteristic of anaerobic microorganisms?

Answer 13

Can survive without oxygen.
cellular respiration: redox reaction is used to move electrons around to produce ATP.
Metabolic Adaptations: Anaerobic microorganisms utilize alternative electron acceptors in their metabolic pathways instead of oxygen

Oxygen Sensitivity: Anaerobic microorganisms are sensitive to oxygen and may be inhibited or killed by its presence.

Habitat Adaptations: They thrive in environments with low or no oxygen, such as sediments, wetlands, and the gastrointestinal tracts of animals

Question 14

Why are sulfate reducing bacteria more competitive than methanogens?

Answer 14

Sulfate reduction is energetically more favorable than methanogenesis. Sulfate reducing bacteria SRB can generate more ATP per molecule of organic substrate compared to methanogens. This higher energy yield allows SRB to outcompete methanogens for shared substrates.

Question 15

What is cellulose?

Answer 15

Cellulose is a complex carbohydrate, specifically a polysaccharide, that serves as a structural component in the cell walls of plants.
Very long chain polymer of glucose ~10,000 in wood. Cellulose links up in multiple bundles to make fibres. Tight bundles are very resistant to chemical attack

Question 16

What is branched metabolism?

Answer 16

Branched metabolism refers to metabolic pathways with multiple alternative routes for converting substrates into different products, enhancing metabolic flexibility and adaptability

Question 17

In which domain of life are methanogens belonging?

Answer 17

STIKORD: Archea, anaerob respiration
CO2+4 H2–> CH4+2H2O

Methanogens belong to the domain Archaea. They are a group of microorganisms within the Archaea domain that produce methane (CH4) as a metabolic byproduct of their anaerobic respiration. Methanogens are known for their ability to thrive in extreme environments such as anaerobic sediments, wetlands, and the gastrointestinal tracts of animals.

Question 18

Which is the main purpose of lignin in plants?

Answer 18

The main purpose of lignin in plants is to provide structural support and strength to plant tissues.

Question 19

What is Power to X?

Answer 19

Convert renewable electrical energy to X suck as hydrogen, methane, methanol.

Question 20

Mention 3 biogas upgrading technologies

Answer 20

Cryogenic separation: In cryogenic separation, biogas is cooled to very low temperatures, causing the components to condense into liquid form. The impurities such as CO2, water vapor, and other trace gases are removed as liquids, leaving behind purified methane gas

Membrane separation: Membrane separation utilizes semipermeable membranes to selectively separate gases based on their molecular size and permeability. The membranes allow methane to pass through while capturing impurities such as CO2 and H2S, resulting in purified methane gas’

Organic solvent scrubber: In an organic solvent scrubber, biogas is passed through an organic solvent, which selectively absorbs impurities such as CO2 and H2S. The purified biogas is then separated from the solvent, which can be regenerated for reuse.
amine scrubber: An amine scrubber works similarly to an organic solvent scrubber but uses aqueous solutions of amines to absorb CO2 and H2S from biogas. The absorbed impurities are then stripped from the solvent using heat or pressure, leaving behind purified biogas.

PSA: PSA involves passing biogas through adsorbent materials under high pressure. The adsorbent selectively captures impurities such as CO2 and H2S, allowing purified methane gas to be released at lower pressure. Periodic pressure changes regenerate the adsorbent material for reuse.

Water scrubber: In a water scrubber, biogas is bubbled through a water-based solution. The impurities such as CO2 and H2S dissolve in the water, leaving behind purified methane gas. The water solution can be treated to remove the absorbed impurities, allowing for the regeneration of the scrubbing medium.

Question 21

What it means that an organism is phototroph

Answer 21

is an organism that can use visible light as a primary energy source for metabolism, a process known as photosynthesis. Phototrophs contrast with chemotrophs, which obtain energy from the oxidation of organic compounds.

Question 22

which two catagories can metabolism be splitted into?

Answer 22

Anabolism: energy requiring. From simpler molecules to complexer.
Catabolism: Energy yielding. complex to simpler.

Question 23

What is metabolism?

Answer 23

Metabolism: All activities inside
the cell

Question 24

What is the electron transport chain?

Answer 24

Series of proteins located at the inner membrane of the mitrocondria.
NADH (electron carrier) delivers the e- to the first protein in the chain. As the electrons are moving through the protein, energy is released, which is used to pump H+ across the inner membrane (from matrix to intermebrane space).
The e- are then transported to the next protein where FADH2 donates new e-. Then all e- are transported to the next protein, where the electricity is used to transport the H^+ again. The same happens in the next protein.
High concentration of H^+ n intermbrane space is builded. And high conc. of e^- at the protein is build. Eoectronacceptors are needed (example Oxygen) to carry away the accumulated electrons. If this happens the electron transport chain stops and wont be able to produce ATP and keep u alive.
The high conc. of H^+ is used to generate ATP through a protein ATP synthase that creates a channel that allows H^+ to flow through due to a conc. gradient. This transport forces the ATP synthase to spin and produce ATP.

Question 25

Why is algae a risk for the life in seas?

Answer 25

Algae degrade. This proces consume oxygen leading to removal of oxygen from the water.

Question 26

How are mircrobes used in treatment of wastewater?

Answer 26

microorganisms remove organic carbon (COD), fixed nitrogen (NH4+,NO3-), phosphorus from waste streams in activated sludge. Aerobic and also anaerobic treatment in large mixed tanks/reactors.

Question 27

What are chemotrophy vs Phototrophy?

Answer 27

Depends on the type of energy sources.
Chemotrophy: chemicals, organic chemicals
Phototrophy: Light as energy source.

We use organic chemicals.

Answer 28

Energy source: Chemotroph (%light)
Electron source: Organotroph
carbonsource:

Question 29

What is carbon cycling?

Answer 29

0.004% CO2 in atm. Used in animals and microorganisms in respiration.

Question 30

What are biogeochemical cycles?

Answer 30

The turnover or cycling of elements or moelcules.
Before the industrialisation these cycles were in harmony.

Disturbing one cycle will affect the others .

Core earth elements: Carbon, Nitrogen, Hydrogen, oxygen phosphorous, sulfur

Question 31

What is the difference between aerobic and anaerobic carbon decomposition?

Question 32

What is microbial growth?

Answer 32

Bacteria replicate their genetic material and carry-out chemical transformations which allow the synthesis of all the constituents from various precursors and energy.

Question 33

How do we measure growth?

Answer 33

Different ways:
NUmber of indiciduals:
count cell numbers => direct count under microscopes in grids over time t. A small DNA is added, which can go inside the microbes we want to study. THey will light up.

Viable (plate) Count: Growth of a small sample => a colony.

Density measurement:
Turbidity: Measure optical density to have an idea of how many microbes is in the culture. Count everything,

Amount of mass:
Weighting of the bacteria culture.

Question 34

1. Phase of bacteria growth

Answer 34

Lag: Physiological adaption of the cells to the culture conditions. The bacteria have to adapt to the environment before the growth can start. This phase is the lag phase.
The growth rate is zero dX/dt=0

Question 35

2. Phase of bacteria growth

Answer 35

The exponential phase. Starts when initial population has doubled. Which can be described mathematically.
After n generations:
X_(t+n)=2^n*X(t)

The exponetial model supposes the specific growth rate is constant. But it is not the case, when we run out of substrate then the growth will stop.

Question 36

Difference beween growth rate and specific growth rate

Answer 36

Bac1:
20g–>40g
5 min
Bac2:
40g–>80g
5 min

Growth Rate:
Amount of biomass prdouced/time
B1=(40-20)/5=4 g/min
B2=(80-40)/5=8 g/min

Specific growth rate:
Amount of biomass prdouced/(timeinitial[biomass])
B1=(40-20)/(205)=0.2 min^-1
B2=(80-40)/(40*5)=0.2. min^-1

The specific growth rate is the same but the growth rate is not. Growth rate increase with time.
Specific growth rate is the slope.

Question 37

3. Phase of bacteria growth

Answer 37

the stationary phase: no net growth dX/dt=0.
Substrates are running out, growth on dead cells.

Growth is balanced by an equal number of cells dying.

Question 38

What does the Monod equation describes?

Answer 38

S: substrate
X: concentration of cells.

More substrate => higher rate of X dX/dt
More X => more substrate consumed.

Exponential growth model need to be modified.
Specific growth rate as a function of substrate concentration.
Monod equation (more or less the same as Michaelis-Menten eq.): Microbial growth curve, describes the specific growth rate due to synthesis as a function of substrate concentration.

K: tells how much substrate needed to achieve high specific growth rate.

Question 39

4. Phase of bacteria growth

Answer 39

The death phase.
More cells die than divide.
b: specific death rate or decay rate [1/d]
S_min: the minimum amount of substance where the cells can not divide but only maintain.

Question 40

What is aerobic mineralization?

Answer 40

A part of the carbon cycle. Decomposition og COD with O2.. COD get oxidized to CO2 and loosing one electron. This electron is reduced by accepting the electron and forming H2O

COD+O2–>CO2+H2O

COD could for instance be Glucose. Glucose is then Electron donor and O2 is acceptor.

Question 41

The 3 types of energy metabolims

Answer 41

Energy Source:
- light=> Phototroph
- Without Light=> Chemotroph

Electron Source:
- Inorganic=> lithotroph
-Organic=> Organotroph

Carbon Source:
- CO2=> Autotroph
- Organic-C=> Heterotroph

Question 42

How is microbial biomass used in wastewater treatment

Answer 42

They remove organic carbon and fixed nitrogen (NH4^+, NO3^-)

Bacteria can convert organic carbon to CO2.

Question 43

What is nitrification?

Answer 43

Oxidation of ammonium with O2 as electronacceptor forming nitrate. Two steps. NH4+–>NO2^- by one microbe
and
NO2^- –>NO3^- by another microbe.