Microbial Biotechnology Midterm

Symbiosis

From Greek endo, meaning “inside,” and symbiosis, meaning “to live with”

• Mutualism

• Commensalilsm

• Parasitism

• Amensalism

Mutualism

both symbionts and hosts benefit

Ex: Human guts provide a moist environment and nutrients for gut microbiota and microbes provide vitamin precursor

Commensalism

One symbiont benefit without affecting the other

Ex: Staphylococcus aureus (S. aureus) is a commensal bacterium that can live on human skin without causing disease

Parasitism

Host is damaged while symbionts benefits

Ex: Mycobacterium tuberculosis in human lungs

Amensalism

One symbionts is harmed while second symbiont is unharmed/benefit

Microflora (microbiota)

Microbes that colonize the body without causing disease

______ protects fetus from microbes.

Amniotic membrane and fluid

Commensal organism

• an organism that lives in close association with another organism

• Microbes normally found at various nonsterile body sites

Resident microbiota

• A part of normal microbiota throughout life

• Mostly commensal

• Found on skin and mucous membranes (of the digestive tract, respiratory tract, distal portion of urethra, and vagina)

Transient microbiota

• Duration: 1 hour to months

• Found in the same regions as resident microbiota

• Cannot persist because:

  • Competition from other microorganisms

    • Transient outnumbered resident microbiota because of anitibiotics

  • Elimination by the body’s defense cells

  • Chemical or physical changes in the body

Upper Respiratory Tract Resident Microbiota

• Microbiota of the trachea and bronchi are sparse compared to those in nose and mouth

• Microbes in alveoli are axenic → no natural microbiota

Axenic microbe

a microbe that is grown in a culture free of other organisms

Upper Digestive Tract Resident Microbiota

• Microbes colonize surfaces of teeth, gingiva, lining of cheeks, and pharynx

• Microbes found in large number in saliva

• Dozens of unidentified microbes

Lower Digestive Tract Resident Microbiota

• Strictly anaerobes bacteria, while some facultative anaerobes are also resident

• Stomach bacteria love acidic enviroment

Female Urinary and Reproductive Resident Microbiota

• Microbiota changes based on the menstrual cycle because of acidity changes

• Urine flow prevents extensive colonization in urethra & bladder

Male Urinary and Reproductive Resident Microbiota

• Urine flow prevents extensive colonization in urethra & bladder

Eye & Skin Resident Microbiota

• Microbiota live in dead layers of the skin and hair follicles of the epidermis

• Microbiota in dermis and hypodermis are axenic

• Tears washes microbiota from eyes

_______ prevents microbial contamination and newborns get established their microbiota during ___ from their ___.

• Anemiotic fluid and placenta

• 1st month of life

• Environment (breathing, breast feeding, etc.)

Microbial antagonism

• The competition between normal microbes and pathogens for nutrients and space

• Reinforces the body’s defense by limiting the ability of pathogens to colonize the skin and mucous membranes (synthesizing antimicrobial compound)