BIO 6 - Microbiology

Question 1

What is the number of bacteria on earth estimated to be?

Answer 1

5*10^30

Question 2

Name three groups of microorganisms

Answer 2

1. Viruses
2. Prokaryotes (Bacteria, Archaea)
3. Eukaryotes (Fungi (mold, yeast), Algae, Protozoa, Slime molds (protists = numerous
   microbial eukaryotes))

Question 3

What is the difference between prokaryote microorganisms and eukaryote microorganisms?

Answer 3

Prokaryote comes from the Greek πρό (pro, ‘before’) and κάρυον (karyon, ‘nut’ or ‘kernel’)
INGEN KERNE
eks. bacteria

Eukaryota or Eukarya comes from the Greek ε (ὖ eu,
‘well’ or ‘good’) and κάρυον (karyon, ‘nut’ or ‘kernel’)
KERNE

Question 4

What is the tree of life?

Answer 4

The tree of Life consists of:
1. Bacteria
2. Archaea
3. Eukarya (animale)

It is the tree domains of living organisms.
1. and 2. => is called prokaryotes

Question 5

How do bacteria proliferate? (formerer)

Answer 5

A process called binary fission
1. duplication of the bacterial cell’s genetic material (DNA). DNa molecule replicates, producting two identical copies.
2. The cell elongates and the copies of DNA moves away from eachother
3. The cell divides into two daughter cells.

1–> 2 cells

Question 6

What is the generation time (time for 1 cell to become 2) for vibrios and for pelagibacter?

Answer 6

Generation time: time for 1 cell to become 2
10-20 min for vibrios,
20-50 h for Pelagibacter

Question 7

How is bacterial growth rate calculated?

Answer 7

In the exponential phase the number of cells at time t (N) is:
N(t)=N0exp(mu(t-t0))

mu: specific growth rate, rate of increase of cells per biomass (h^-1).
N0: number of cells at time 0.

Question 8

What do bacteria and archae have in common (as opposed to eukaryotes)?

Answer 8

They do not have:
- a distinct nucleus, but the genetic material is dispersed in the cytoplasm
- membrane-bound orgenelles such as mitochondria and endoplasmic reticulum

They only have:
- single circular chromosome whereas eukarytoes have multiple linear chromosomes

They reproduce primarily through binary fission

Question 9

How can CO2 absorption of the ocean be facilitated (Phytoplankton)?

Answer 9

Phytoplankton such as Emiliana huxleyi (Eh), can absorb CO2 during photosynthesis. It uses it as a carbon source to buid their biomass.
Eh contains DMSP that can be converted by enxymes (DMSP lyase) into DMS.
DMS is released into the atmosphere and is oxidated to form sulfur compounds.
These act as cloud condensation nuclei (CNN) when they accumulate in the atmosphere.
Clouds impact climate becuase they reduce the amount of solar radiation that reaches Earth.
COOLING EFFECT on the climate

Question 10

What is meant by ocean acidification?

Answer 10

A lot of CO2 is storage in the ocean. But when CO2 dissolves in seawater it reacts and form carbonic acid (H2CO3)=> Which lowers the pH of seawater (more acidic). => H2CO3 can dissociate into HCO3- +H+ further decreasing the pH of seawater.

The pH of seawater has been decreasing over time due to the absorption of CO2 from the atmosphere.

This acidification can cause:
impact on marine life,

Question 11

What is iron fertilization?

Answer 11

Adding iron to regions of the ocean to stimulate the growth of phytoplankton => enhance the capture of CO2 from the atm.

Risk:
Can also lead to large algal blooms (algeopblomstring)
a type is Pseudo-nitzschia that can produce domoic acid =>amnesic shellfish poisoning=>toxic to mammals, sea lions, seals, humans

Question 12

What are (som of the) adverse effects of microorganisms? (skadelige virkninger af mikroorganismer)

Answer 12

1. Microorganisms, particularly bacteria (tuberculosis ), viruses (influenza and COVID-19), fungi (athlete’s foot and candidiasis), and parasites (malaria and giardiasis), can cause infectious diseases in humans, animals, and plants.
2. Food Spoilage and Foodborne Illnesses
   Bacteria such as Salmonella, Escherichia coli (E. coli)

Question 13

Name some (biotechnological) uses of microorganisms

Answer 13

• Fermentation; microorganisms such as bacteria, yeast and fungi are used in fermentation processes to produce a wide range of products (alcoholic, cheese, bread, biofuels)
• Pharmaceutical Production; microorganisms are used to prudce pharmacerutical products (penicillin, inslulin, vaccines against diseases like hepatitis B)
• Waste-water, bioremediation

Question 14

What is a microbiome

Answer 14

The community of microorganisms that are living together in any given habitat.

Question 15

What is meant by synthetic biology?

Answer 15

• redesigning organisms for useful purposes by engineering them to have new abilities.

Question 16

How can one determine the abundance (antal) of microorganisms in a niche?

Answer 16

microscopy (directly counting) or by DNA-based methods (Sequencing of DNA (and RNA) has revolutionized our ability to study (and use) microbiomes)

Question 17

How can one determine the functions of microorganisms in a niche?’

Answer 17

Metagenomics (sequencing all genes from a sample): sequencing the collective genomic DNA of microorganisms directly from environmental samples => information on their functional roles based on the presence of specific genes and metabolic pathways.

Question 18

How do bacteria evolve (so rapidly)?

Answer 18

• short generation time
• large population sizes, greater change of benficial mutations
• Horizontal gene transfer (through conjugation, transduction, transformation, gene transfer agents)
  Exponential growth

Question 19

What is the advantage of heterogeneity in a
microbial population?

Answer 19

• difference in traits makes adaptation to different environments possible
• variation provides resilience against stressors and predators
• generates genetic variation for evolution

Question 20

Why can rRNA gene be used as a phylogenetic marker of all life?

Answer 20

Ribosomes consists of rRNA (and Protein). The rRNA gene sequences can be compared among various organisms. It is possible to make a family tree that shows hoe the different species are related to each other over evolutionary time.
- rRNA genes are present in all cellular organisms.
- rRNA has a stability over evolutionary time.

Question 21

Name one disadvantage and one advantage of bacterial biofilms

Answer 21

Biofilms are dense mixed
communities. Bacteria likes to stick to things. Forming a thin film of bacteria.

Disadvantage: Corrosion, infection - implants, chronic infections
They are hard to remove.

Advantage: High resistance to environmental stresses

Can be used in:
- Water treatment
- Gut microbiome
- Plant protective bacteria
- Biofilm based fermentation
- Plant growth

Question 22

Why do bacteria become antibiotic resistant?

Answer 22

It means that it has acquired the ability to survive and grow in the presence of an antibiotic that would normally inhibit or kill it.

This resistance can occur through various mechanisms, such as genetic mutations or the acquisition of resistance genes from other bacteria.

This can be a significant challenge in healthcare as it limits the options for treating bacterial infections

Question 23

How and where can new antibiotics be discovered?

Answer 23

• Sequencing genomes of microorganisms (genomics)
• Sequencing all genes from a microbiome (metagenomics)
• ”Mining” (searching sequence) for homologous sequences gene clusters encoding core domains of enzymes synthetsizing antibiotics (antiSMASH)
• Predicting chemistry based on sequence of Biosyntehtic Gene Clusters
• Chemistry from 70-90% of BGCs not known/discovered
• Ai (ML) based approaches?

Question 24

What is conjugation?

Answer 24

Exchanging genes in horizontal gene transfer, Genetic transfer by direct contact

Question 25

What is Transduction?

Answer 25

Transduction is mechanism of horizontal gene transfer in bacteria, facilitated by bacteriophages, which are viruses that infect bacteria.

The genetic transfer happens through a viral vector (bacteriophages).

Question 26

What is Transformation?

Answer 26

Exchanging genes in horizontal gene transfer, Uptake of exogenous genetic material:

Transformation is a process of horizontal gene transfer in bacteria where the cell takes up free DNA from the surrounding environment and incorporates it into its own genome. This DNA can come from the lysis of other bacterial cells, released plasmids, or fragments of DNA shed by dead bacteria

Question 27

What is Gene transfer agents?

Answer 27

Gene transfer agents (GTAs) are small, virus-like particles produced by certain bacteria. They facilitate the transfer of genetic material, such as DNA fragments, between bacteria within a population. GTAs play a role in horizontal gene transfer, contributing to genetic diversity and evolution among bacterial populations.
THESE ARE PRODUCED BY THE BACTERIA THEMSELVES TO TRANSFER DNA FRAGMENTS