Day 2 part 2 biofilm & ARGs

Environmental Biotechnology

🧩 The “One Health” Concept

Definition: ➡️ One Health is an integrated, unifying approach that links the health of humans, animals, and ecosystems. All three depend on each other — if one is unwell, the others suffer too.

Core idea: 🌿 Healthy soil → 🐄 healthy animals → 🧍‍♂️ healthy people → 🌍 healthy planet.

Requires:

Collaboration between doctors, veterinarians, ecologists, microbiologists, policymakers.
Sustainable practices in agriculture, waste management, and medicine.

Example: Poor soil health → nutrient runoff → contaminated water → animal illness → human disease. Everything is connected. 🔄

🦠 Antibiotics and Antimicrobial Resistance (AMR)

💊 What are antimicrobials?

Drugs that kill or inhibit microorganisms:

Antibiotics → bacteria 🧫
Antivirals → viruses 🦠
Antifungals → fungi 🍄
Antiparasitics → parasites 🪱

We mainly focus on antibiotics, as resistance here is the most critical.

🚫 Antibiotic Resistance

Resistance = when bacteria evolve so antibiotics no longer work.

How resistance develops:

Mutation – Random DNA changes give survival advantage.
Horizontal gene transfer (HGT) – Bacteria share resistance genes via plasmids or transposons.
Overuse and misuse – Frequent antibiotic use increases selection pressure.

Result: “Superbugs” that normal drugs cannot kill. 🧬🧟‍♂️

⚙️ Mechanisms of Action (How antibiotics work)

Antibiotics target features unique to bacteria (so humans aren’t harmed):

Mechanism	Target	Example
1️⃣ Inhibit cell wall synthesis	Peptidoglycan	Penicillin
2️⃣ Inhibit protein synthesis	Ribosomes (70S)	Tetracyclines
3️⃣ Inhibit nucleic acid synthesis	DNA/RNA enzymes	Quinolones
4️⃣ Disrupt metabolism	Folate synthesis	Sulfonamides
5️⃣ Damage cell membrane	Permeability	Polymyxins

🧠 Humans are safe because our eukaryotic cells lack bacterial cell walls and have different ribosomes (80S).

🧪 Mechanisms of Resistance

Bacteria evolve countermeasures:

Mechanism	Description
🔄 Target modification	Changes antibiotic binding site
🧹 Efflux pumps	Pumps drug out of cell
✂️ Enzymatic degradation	Breaks antibiotic molecule (e.g., β-lactamase)
🧬 Gene transfer	Spreads resistance genes between species

Resistance genes can persist naturally in soil or water — even ancient Arctic sediments contain them, showing this is an old evolutionary phenomenon. ❄️🧫

🧫 Natural Origins of Resistance

Before humans existed, microbes already fought each other using natural antibiotics (e.g., Streptomyces species produce many). 👉 They evolved resistance genes for self-defense. Now, these genes can transfer to pathogens via HGT — creating modern AMR.

🐖 Antibiotic Use in Agriculture

Historically, antibiotics were added to animal feed to promote growth and prevent disease (“prophylactic use”).
🛑 Now banned in Denmark and most EU countries.
Main issue: selection pressure in livestock → resistant bacteria → transfer to humans via food chain or environment.

📉 In Denmark: After the ban (1990s), total antibiotic use stabilized or slightly decreased — a success story 🇩🇰.

🌍 Environmental Spread and “Hotspots”

Antibiotic resistance genes (ARGs) move through the environment via:

💧 Wastewater and sludge
🚜 Agricultural runoff
🏭 Pharmaceutical industry effluent
🐷 Animal manure

🧩 Hotspots = wastewater treatment plants, sludge, soil, and animal environments. Resistant bacteria can persist and multiply there, but direct human infection from the environment is rare — still mainly human ↔ animal or human ↔ human transmission.

🧠 Why New Antibiotics Are Rare

Developing new drugs = expensive and risky 💰
Low profit for pharmaceutical companies.
Few new targets discovered.
Resistance emerges quickly after any new drug is released. 💡 Some foundations (like Novo Nordisk Foundation) fund new antibiotic research — but innovation remains slow.

🧭 Global Surveillance & Solutions

🌐 GLASS: Global Antimicrobial Resistance Surveillance System

Started by WHO to:

Track resistance patterns worldwide.
Coordinate data from countries.
Promote awareness and responsible use.

🧰 Key Strategies:

Better surveillance and data collection.
Reduce antibiotic misuse.
Improve wastewater treatment (especially near drug factories).
Encourage R&D for new drugs.
Public awareness — don’t take antibiotics unnecessarily (e.g., for a cold 🤧).

🇩🇰 Denmark Case Study: MicroDanica Project

Collected 10,000+ samples from soil, water, sediments across Denmark.
Screened for ~1,000 known ARGs using metagenomics.
Found:
- 💧 Wastewater = highest ARG concentration
- 🌾 Soil = lower levels
- 🌊 Marine sediments = lowest
Agricultural samples excluded due to political reasons (farmers feared media backlash).
Overall: low ARG levels in Denmark compared to many countries — due to strict antibiotic policies and responsible use.

🧭 Summary of Takeaways

Topic	Key Idea	Emoji
🌎 One Health	Human, animal, ecosystem health are inseparable	♻️
💊 Antibiotics	Target bacterial-specific structures	⚙️
🧬 Resistance	Natural and human-driven evolution	🔄
🧫 Mechanisms	Mutation, HGT, enzyme degradation	🧠
🐄 Agriculture	Overuse → resistance spread	🚜
🌊 Environment	Reservoirs of ARGs	💧
🧭 Surveillance	GLASS monitors global trends	🌐
🇩🇰 Denmark	Leading in antibiotic regulation	🇩🇰
🚫 Solution	Awareness, stewardship, innovation	💡

Quiz

Score: 0/30 (0%)

Q0. What is the central idea of the One Health concept?

Human health is independent of ecosystem health

Animal health is more important than environmental health

Human, animal, and ecosystem health are interconnected

Only microbial health affects humans

Q1. Which ecosystem component was highlighted as especially relevant to One Health in the lecture?

Desert air quality

Soil health

Ocean salinity gradients

Glacial sediments

Q2. What is considered the primary driver of increasing antibiotic resistance globally?

Climate change alone

Low bacterial mutation rates

Overuse and misuse of antibiotics

Decrease in human population density

Q3. Which antimicrobial class targets bacteria specifically?

Antifungals

Antivirals

Antibiotics

Antiparasitics

Q4. Why are few new antibiotics being developed?

Because resistance no longer develops

Lack of scientific knowledge

High cost and low commercial incentive

Governments have banned antibiotic R&D

Q5. Which mechanism allows bacteria to share resistance genes between species?

Vertical gene inheritance only

Passive diffusion

Horizontal gene transfer

Photosynthesis-driven mutation

Q6. Which antibiotic action targets bacterial ribosomes?

Cell wall synthesis inhibition

Protein synthesis inhibition

Membrane disruption

DNA methylation

Q7. Why do antibiotics generally not harm human cells?

Humans metabolize all antibiotics instantly

Human cells lack bacterial structures like peptidoglycan

Antibiotics cannot enter human cells

Human immune cells destroy antibiotics

Q8. What happens when antibiotics kill beneficial bacteria in the human body?

Beneficial bacteria become stronger

Resistant bacteria may expand due to reduced competition

Human cells begin producing antibiotics

Pathogens lose access to nutrients

Q9. What natural source produces many clinically used antibiotics?

Archaea

Marine algae

Streptomyces bacteria in soil

Human skin microbiota

Q10. Why is understanding soil microbial dynamics important for One Health?

Soil microbes cannot evolve

Soil environments have no resistance genes

Soil influences nutrient cycles, emissions, and ARG reservoirs

Soil is unrelated to human health

Q11. What is a major risk of antibiotic residues from pharmaceutical manufacturing entering waterways?

They sterilize the environment

They serve as a nutrient source for bacteria, increasing resistance development

They increase water pH

They boost fish immune systems

Q12. Which environment generally exhibited the highest abundance of antibiotic resistance genes in Denmark’s survey?

Marine sediments

Agricultural soils

Wastewater samples

Grassland soils

Q13. Why did agricultural soils not appear in the ARG comparisons of the Danish dataset?

They contain no ARGs

They were politically excluded from analysis

Sampling was technically impossible

They were contaminated

Q14. What distinguishes wastewater treatment from natural water bodies in terms of resistance burden?

Treatment removes most ARG-containing bacteria

Treatment increases ARG levels

Natural waters have higher ARG concentration

ARGs cannot survive treatment processes

Q15. True or false: One Health emphasizes that human health can be fully understood without considering environmental factors.

True

False

Q16. True or false: Growth-promoting antibiotic use in livestock was banned in Denmark, leading to stable or reduced overall antibiotic use.

True

False

Q17. True or false: Antibiotic resistance genes existed in nature long before humans discovered antibiotics.

True

False

Q18. True or false: Antibiotic resistance spreads only through vertical inheritance from parent to offspring.

True

False

Q19. True or false: Some bacteria can pump antibiotics out of their cells using efflux mechanisms.

True

False

Q20. True or false: Many resistance genes in the environment directly cause human disease.

True

False

Q21. True or false: Differences between bacterial and human ribosomes allow selective targeting by antibiotics.

True

False

Q22. True or false: Pharmaceutical companies are highly motivated to develop new antibiotics due to high profit margins.

True

False

Q23. True or false: Wastewater samples in Denmark showed lower ARG abundance than natural marine sediments.

True

False

Q24. True or false: Antibiotics can be used prophylactically in some livestock systems outside Denmark.

True

False

Q25. True or false: Bacteria may develop resistance by modifying the antibiotic molecule itself.

True

False

Q26. True or false: High antibiotic use in a country correlates with increased resistance risk.

True

False

Q27. True or false: Surveillance approaches like GLASS help track global resistance trends.

True

False

Q28. True or false: Wastewater effluent from pharmaceutical factories can create hotspots for resistance evolution.

True

False

Q29. True or false: Denmark shows lower antibiotic resistance levels compared to many other countries due to controlled antibiotic use.

True

False