Brock Final

What Are Microbes Doing for the Planet

Microbes run the biosphere, Only a tiny percentage cause disease. Most are essential for life. They help keep biogeochemical cycles running—carbon, nitrogen, sulfur, phosphorus.

Producers

Some bacteria (like cyanobacteria) make their own food using sunlight.

Consumers

Some microbes eat other organisms.

Decomposers

Microbes break down dead material and waste, returning nutrients to the ecosystem.

Carbon Cycle

Bacteria ferment milk to make yogurt, kefir, sour cream, cheese. The taste depends on the microbe, type of milk, and fermentation time. Common yogurt bacteria: Lactobacillus bulgaricus and Streptococcus thermophilus

Microbes used in food

Yeasts, like Saccharomyces cerevisiae, ferment sugar, producing ethanol and CO2 gas—CO2 makes bread rise and the ethanol evaporates

Pasteurization

Heating the wine (mildly), then adding good yeast

Microbes useful in science

They grow fast. They're inexpensive to grow. They help with genetic engineering. They helped decode the human genome. They are used in gene therapy

Bioremediation

Using microbes to break down pollutants

immune system

recognizes what belongs in your body ("self") and attack what doesn't belong (microbes, toxins, abnormal cells). It is a network of cells, tissues, and organs working together to keep you healthy

Immunity Develops

Before Birth,A baby's immune system learns what is "self" during pregnancy

At Birth & Infancy

Babies start making their own antibodies, but their immune system is still developing. Immunity gained from the mother fades after weeks to months. If the immune system mistakes "self" as "non-self," autoimmune disease can develop.

Vaginal Birth

receive important microbes from their mother

C-section

Babies often have a different early microbiome, which may affect early immune development

Natural "entry points"

eyes, nose, mouth, skin openings

First Line

Mechanical & Chemical Barriers (Nonspecific). Always working. Keep germs out.

Second Line

Inflammatory Response. Activated when the first line is broken. Nonspecific, fast, no memory.

Third Line

Adaptive Immunity. Slow but extremely accurate. Learns and remembers (antibodies, T-cells, B-cells).

Skin(First Line)

Tough, waterproof, and hard for germs to penetrate. Normal skin bacteria prevent harmful bacteria from growing. Sweat contains lysozyme, which breaks down bacteria. is acidic (pH 3-5), which many germs can't survive.

Non-Intact Skin

Any cut, scrape, or puncture = easy entry point for microbes

Eyes(First Line)

Blinking removes particles. Tears wash away microbes and contain lysozyme. Eyelashes help block debris.

Ears(First Line)

Ear hairs and earwax trap dust, debris, and microbes. Narrow, twisting ear canal makes entry difficult.

Mucous Membranes(First Line)

Covered in mucus that traps microbes. IgA antibodies help neutralize germs. Normal bacteria occupy space so pathogens can't take over.

Nose(First line)

Nose hairs trap particles. Mucus + cilia move particles out ("mucociliary escalator"). Sneezing and runny nose flush microbes.

Lungs(First Line)

Mucus and cilia trap germs and push them out. Coughing and sneezing remove irritants. Lower lungs contain macrophages (cells that "eat" microbes).

Mouth(digestive system defense)

Saliva contains mild antibacterial chemicals. Normal mouth bacteria compete with harmful microbes. Chewing breaks down food and exposes germs to defenses.

Stomach(DSD)

Extremely strong acid (pH 1.5-3.5) kills most microbes. Special cells create protective chemicals.

Intestines(DSD)

Produce chemicals that kill or weaken germs. Peristalsis (movement of the gut) pushes harmful microbes out. Bile salts & lysozyme kill bacteria. The appendix may help repopulate healthy gut microbes.

Elimination(DSD)

The anus is designed for "outgoing," not incoming. Thin tissue + high blood flow = high infection risk.

Urinary System Defenses

Mucus and lining act as physical barriers. Healthy urinary microbes protect against infection. Peeing regularly flushes out germs. Urine is acidic → bad for microbes. Hydration increases flushing. Male vs. female anatomy affects UTI risk (shorter urethra in females).

Female(Reproductive defense system)

Vaginal lining acts as a barrier. Lactobacillus ("good bacteria") dominates. Converts glycogen to lactic acid, lowering pH → prevents harmful bacteria & yeast.

Male(reproductive Defense system)

Semen contains chemicals that reduce immune reaction so sperm can survive. Exterior genital area has no mucosal protection → easier for bacteria to enter.

Blood

Moves white blood cells where they're needed. Carries antibodies that tag or block germs. Delivers oxygen and nutrients to immune cells. Helps with inflammation by widening blood vessels. Removes toxins and waste after germs are destroyed.

White Blood Cells

Pus = mostly dead WBCs and microbes. WBCs are colorless, unlike red blood cells. Made in bone marrow. Many live hours to days; some live years. Can leave the bloodstream to fight infections. Only 1% of blood volume, but extremely powerful.

Inflammation

Triggered when the first line of defense is breached. Non-specific response to infection OR injury. Purpose: bring immune cells to the area quickly. Symptoms: redness, heat, swelling, pain. Can last hours to weeks depending on severity.

Adaptive (Acquired) Immunity

Very specific. Slower to react the first time. Remembers germs and responds faster next time. Includes B-cells, T-cells, and antibodies. Basis for how vaccines work.

Pathogen

Something that causes disease (virus, bacteria).

Antibodies

A protein that recognizes and helps destroy germs.

Antigen

A piece of a germ that triggers an immune response.

Inflammation

Body's alarm + defense reaction.

Macrophage

A "big eater" cell that swallows germs.

Lysozyme

An enzyme that destroys bacteria.

Normal Flora

The good bacteria living on and in you

Mucus

Sticky fluid that traps germs.

Adaptive Immunity

Learned, memory-based immunity.

Innate Immunity

Fast, nonspecific immunity you're born with.

Triggers Inflammation

Cellular injury. Temperature changes. Ionizing radiation. Oxygen deprivation. Environmental toxins. Organ failure. Introduction of foreign bodies (e.g., splinters). Dead microorganisms (e.g., endotoxins). Parasites. Dead host cells

Purpose of Inflammation

Restore homeostasis. Recruit defensive cells. Prevent further injury. Remove debris. Begin repair

Rubor

Redness. Increased blood flow in, limited flow out

Calor

Heat. Blood flow + pyrogens

Tumor

Swelling. Fluid accumulation and cytokine release

Dolor

Pain. Warns not to use the injured area

Acute Inflammation

Short-term. Causes: cuts, sprains, tonsillitis, acute bronchitis, appendicitis. Usually beneficial and resolves

Chronic Inflammation

Persistent low-level inflammation. Contributes to chronic diseases:. Diabetes, cancer, cardiovascular disease. Alzheimer's, arthritis. Autoimmune disorders. Pulmonary disease

Risk/Contributing Factors

Overeating. Stress. Poor sleep. Obesity. High sugar/processed foods. Environmental toxins. Chronic infections. Food sensitivities. Family/genetic factors. Hormone imbalances

Homeostasis Refresher

pH balance. Electrolytes (Mg, Ca, K, Na). Stable temperature. Blood pressure. Fluid balance. Blood glucose. Reflexes

Live Attenuated(Vaccine)

Example: cowpox, nasal flu. Weakened version of virus

Killed (Inactivated) Organisms(Vaccine)

Seasonal flu, Rabies, Typhoid (Polio varies by formulation)

Passive Immunity(Vaccine)

Does not create long-term memory. Examples: Gamma globulin for Hep A; Ebola antibody treatments

Virus-Like Particles (VLP)(Vaccine)

Genetically engineered,Examples: HBV, HPV.Live-vectored vaccines (e.g., Ebola)

Booster Shots(Vaccine)

Required for HBV, Polio, Shingles, Pneumonia, etc. Purpose: reinforce immune memory

Mutational Drift and Shift

Occurs in viruses like influenza and coronavirus. Changes antigens → partial or full immune escape

Antigenic Mimicry

Microorganisms share antigenic sites with human tissues. Immune system attacks both. Can contribute to autoimmune disease

Homeostasis

balance between pathogens (like viruses, bacteria) and their hosts

Cytokines

crucial signaling proteins that orchestrate immune responses

Exudation

forming pus or other fluids containing dead cells, bacteria, and immune cells

Pyrogens

bacteria, viruses, and fungi, trigger fever by stimulating immune cells

Memory cells

specialized immune cells (B and T cells) that "remember" a specific pathogen after a first encounter

Endotoxins

Dead Microorganisms

Bio-Weapons

Microbes deliberately deployed to grow in/on the target host. Purpose: cause disease, incapacitate, or kill. Must be deliverable and capable of producing mass casualties

Chemical agent

toxins acting immediately

Biological agent

living microbes requiring incubation, amplification

Characteristics of Effective Biological Weapons

Highly toxic or infectious. Lethal or highly incapacitating. Suitable for mass production and storage. Stable enough to survive environment/transport. Retains pathogenicity over time. May allow genetic engineering or weaponization.

How Biological Weapons Are Developed

Choose an agent (pathogenicity, transmissibility, environmental stability). Acquire the agent. Acquire a production method. Stabilize the agent. Concentrate the agent. Choose a delivery method. Field testing. Mass production. Stockpiling and mobilization

Early Biological Warfare (Ancient → Pre-Modern)

Assyrians poisoning wells. Trojan War disease tactics. Greeks/Romans using dead animals. Mongols catapulting plague-infected corpses. Smallpox blankets given to Native Americans

20th Century Developments

Gruinard Island anthrax contamination. WWII programs in U.S. and abroad. Establishment of USAMRIID for offensive/defensive research

Geneva Protocol

Prohibited use (not development) of biological & chemical weapons

1969 Nixon Decision

Ended U.S. offensive biological warfare program

1972 Biological Weapons Convention (BWC)

Prohibited: Development, Stockpiling, Delivery systems, Required destruction of existing stockpiles

Rise of Modern Bioterrorism

Notable cases: Rajneesh cult salmonella attack (food contamination). Aum Shinrikyo (Tokyo subway sarin attack, also attempted biological). U.S. anthrax letters (2001)

Biological Threats & Agent Categories

Catergory A,B,C

Category A (Highest Priority)

Easily disseminated, high mortality, major public panic. Includes: Anthrax, Smallpox, Plague, Botulism, Tularemia, Viral hemorrhagic fevers (Ebola, Marburg

Category B

Moderately easy to disseminate, moderate morbidity. Examples: brucellosis, Q fever, food/water safety threats

Category C

Emerging pathogens: Nipah, Hantavirus, genetically engineered threats

National Security Considerations

Biological warfare threatens national security through: Public health impact, Fear and civil disruption, High delivery potential, Preparedness challenges

Advantages of biological vs chemical/nuclear

Low cost, ease of production, Difficult detection, Amplification inside victims, High psychological impact