Chapter_10 (microbial ecology)

Ecology: The systematic study of interrelationships between organisms and their environment.
Microbial Ecology: Focuses on interrelationships between microorganisms and their environment.
Most human-microbe relationships are beneficial.
Microorganisms inhabit both the surface and internal cavities of the human body.

Symbiosis: Interaction between two different species living together.
Relationships can change based on the host's condition and microbes' attributes.

Mutualism: Both organisms benefit (e.g., bacteria synthesizing vitamins K and B).
Commensalism: One organism benefits while the other is not affected (e.g., skin flora).
Parasitism/Antagonism: Microbe benefits at the host's expense (pathogenic infections).
Opportunistic Pathogens: Microbes that can shift from harmless to harmful under certain conditions.

Synergism: When two or more organisms collaborate to cause a disease that neither could cause alone.
Known as synergistic infections, polymicrobial infections, or mixed infections.
Example: Bacterial vaginosis (BV).

Beneficial Outcomes:
- Protection against harmful organisms through binding and antibiotic antagonism (e.g., lactobacilli).
- Immune system stimulation and cross-reaction with later encountered pathogens.
Adverse Effects:
- Escape from the immune system leading to multiplied disruptions.
- Consequences of the absence of normal flora include susceptibility to infections.

Germ-free animals display several significant effects:
- Enlarged cecum: Microbes required for development of intestinal tract.
- Vitamin deficiencies: Microbes are important sources of vitamins.
- Underdeveloped immune systems: Microbes are crucial for stimulating immune defenses.
- Absence of dental caries and periodontal disease: Indicative of the role of microbes in disease development.

Normal flora is established during the birth process:
- Mother’s birth canal: Introduces staphylococcus, streptococcus and lactobacilli.
- Breast milk: Contributes Bifidobacterium.
- Bottle-feeding: Introduces enteric bacteria.
Composition of flora is dynamic and changes with physiological variations in the host.

Skin: Dominated by anaerobes found in hair follicles, sweat, and sebaceous glands.
Ears and Eyes: Microbial presence is limited due to enzymes and protective mechanisms.
Respiratory Tract: Includes upper and lower respiratory areas with varied microbial taxa.
Mouth: Hosts flora like gum margins and between teeth.
GI Tract: Includes esophagus, stomach, intestines, and anus.
GU Tract: Involves kidneys, bladder, urethra, and vagina.

Opportunistic Pathogens: Microorganisms that can cause infections when given the opportunity (e.g., E. coli, S. aureus).
Disruption of the balance of indigenous microflora can occur due to antibiotics, chemotherapy, and pH changes.
Biotherapeutic Agents/Probiotics: Bacteria and yeasts used to restore microbial balance.

Microorganisms often form biofilms (e.g., dental plaque).
Presence of multiple species in clusters called microcolonies.
Biofilms are resistant to antibiotics and produce unique proteins compared to pure cultures.
Medical significance includes formation on devices, which can lead to diseases like endocarditis.
Associated microbes include Candida albicans, Staphylococcus aureus, and others.

Utilized in agriculture (e.g., genetic engineering).
Aid in crucial elemental cycles: nitrogen, carbon, oxygen, sulfur, and phosphorus.

Involves processes like nitrogen fixation, denitrification, ammonification, and nitrification.

Soil contains diverse microorganisms (bacteria, fungi, protozoa).
Pathogens in soil: includes species like Clostridium (such as C. tetani) and spores like Bacillus anthracis.
Organisms' presence influenced by factors such as decaying matter, moisture, oxygen levels, and pH.

Microbes are responsible for numerous plant diseases, primarily caused by fungi, viruses, and bacteria.

Defined as techniques using living organisms or parts to create or modify products.
Microbes in food production: bread, cheese, yogurt, pickles, and alcoholic beverages.
Some antibiotics and drugs are produced from fungi and bacteria (e.g., penicillin).

Process of utilizing microorganisms to clean up pollutants and industrial waste.
Some microbes are genetically engineered for waste digestion (e.g., petroleum-digesting bacteria).
Methanotrophs can remove hazardous solvents from the soil.