Dr. Santiago Martinez (paper/slides)

What is the archaeome?

The archaeal component of host-associated microbiomes

Why has the archaeome been historically overlooked in microbiome research?

Research has primarily focused on bacteria, fungi, and viruses

What are the major contributions of archaea to host health?

They influence digestion, methane production, and disease processes

Which methanogenic archaea is most commonly found in the human gut?

Methanobrevibacter smithii

How do Methanomassiliicoccales potentially benefit human health?

They may help regulate gut microbial interactions

Where can archaea be found in the human body?

Skin, respiratory tract, and gastrointestinal tract

How does the immune system recognize archaea?

Through TLR7 and TLR8, which trigger inflammasome activation

What makes up TACK archea?

Crenarchaeota, Aigarchaetoa, Thaumarchaeota, Korarchaeota

Which archaeal group is important in nitrogen cycling?

Thaumarcheota (N)

Which archaea are considered potential evolutionary links to eukaryotes?

Asgard Archaea

How do archaea interact with protists?

As endosymbionts in anaerobic ciliates, benefiting from hydrogen metabolism

What is the role of archaea in plant root microbiomes?

They affect nutrient absorption

Which animals harbor archaea in their digestive systems?

Ruminants, termites, and cockroaches

What is the relationship between methanogens and protists in ruminants?

Higher protist concentrations correlate with increased methane production

What impact do defaunation experiments have on methane emissions?

Removing protists reduces methane emissions by up to 37%

Which factors influence the presence of archaea in the human gut?

Geography, diet, age, and genetics.

Why do monozygotic twins have more similar M. smithii levels than dizygotic twins?

Due to genetic influences on microbiome composition

How does M. smithii interact with bacteria like Christensenallaceae?

It promotes hydrogen transfer and acetate production

What is the relationship between Methanomassiliicoccales and trimethylamine (TMA)-producing bacteria?

They coexist, influencing gut microbial metabolism

Which archaea dominate the gut microbiome?

Methanogens

Which archaeal group is more abundant on human skin?

Thaumarchaeota

Where are DPANN archaea found in humans?

In the lungs and biopsy samples, but not in stool

What are three key adaptations of archaea in the gut?

Cell surface modifications, biofilm formation, bile salt resistance

What is the function of adhesin-like proteins in archaea?

Help archaea bind to host tissues and bacteria

How do bile salt hydrolases help archaea?

They detoxify bile acids, allowing survival in the intestine

Which methanogen is associated with vaginal infections and colon cancer?

Methanobrevibacter smithii

Which archaea are found in periodontitis and brain abscesses?

Methanobrevibacter oralis

What role do archaea play in inflammatory conditions?

They interact with anaerobic bacteria and may contribute to disease states

T/F: Only methanogens can use methane for methanogenesis

True

What makes up Asgard Archea group?

Lokiarchaeota, Odinarchaeota, Thorarchaeota, Heimdallarchaeota

Methanogenesis

process by which methanogenic archaea produce methane gas without using oxygen

T/F: Methanogens prefer dark conditions

True, they are sensitive to light and are found inside of cows, humans, and sediments

Why do many rumen (cows, sheep, goats) have lots of methanogens in their microbiome?

There is already methanogens in their microbiome inherently, but their high-fiber diet contributes as well

The three main pathways for methanogenesis are:

hydrogenotrophic, acetoclastic, methylotrophic

Hydrogenotrophic

Methanogensis pathway that uses hydrogen gas and carbon dioxide as substrates to produce methane

Acetoclastic

Methanogensis pathway that uses acetate as the primary substrate for methane production

Methylotrophic

Methanogensis pathway that utilizes methylated compounds like methanol or methylamines as substrates for methane production

Why are Methanogens so efficient at consuming the carbon source?

Methanogens can transfer electrons to produce a concentration gradient necessary to produce ATP

What is the “natural carbon source” mentioned in lecture?

Acetate

What is the first step of Methanogenesis?

Once acetate is inside the cell, the methanogenes can use the acetate to produce biomass, methane, and energy.

∆ cam

Important for the metabolism of acetate, but not for methanol

Relationship between pH and methane production?

When pH goes down, methane production goes up (bad for the environment, ocean acidification climate change example)

What is the hypothesis mentioned of why biofilm is inside humans?

Biofilm is inside humans for migration

What was the goal of Dr. Santiago’s project?

To understand how Mathanobrevibacter smithii consumes carbon sources, and the interactions between bacteria/archea and the host/humans

What do euryarchaeota include?

methanogens and other extremeophiles