1 - Humans and the microbial world

creation of living organisms from non-living material

• Francesco Redi
• Louis Pasteur
• John Tyndall

liquid that contains nutrients which support the growth of microorganisms

a kind of resting bacterial cell hightly resistant to heat, radiation, and disinfectants; found abundant in soil and hay infusions

Genus/Genera: Bacillus & Clostridium

chemical used on inanimate objects that eliminates most pathogens (microorganisms and viruses)

nitrogen fixation, oxygen production, degradation of materials (cellulose, sewage, wastewater, oil spills)

yeasts for bread, fermentation of milk (yogurt, cheese, buttermilk)

treat radioactive waste

diversity in the number and distribution of species inhabiting an ecosystem

total weight of all organisms in a specific environment

ehtanol, pesticides, antibiotics, dietary amino acids

introduce genes of one organism into an unrelated organism to confer new properties on the organism

engineering organisms to produce medically important  products and vaccines

pharmaceuticals

engineered plants resist disease

potentially therapeutic (gene therapy)

• modern sanitation
• vaccination
• antimicrobial treatments

• viral disease smallpox (~10 millions deaths over 4,000 years)
• The Black Plague (~25 million individuals)

• most pathogenic bacteria identified
• work on viruses began
• understanding that microscopic agents could cause disease led to control efforts
• huge improvements in past century in human health (antibiotics to treat infectious diseases; vaccines to prevent diseases)

respiratory infections and diarrheal (GI) diseases

disease with increased incidence in the last 20 years; changing lifestyles increase opportunities to spread and evolution of infectious agents previously unable to infect humans

• swine flu (2009)
• SARS (2002)
• MDR-TB
• lyme disease
• hepatitis C (HCV)

• pathogens built up immunity to vaccinations
• lack of firsthand knowledge of dangers of diseases lead people to fear vaccines more than diseases
• declining vaccination rates (measles, mumps, whooping cough nearly eradicated from US)
• increased travel and immigration
• changes in population
• chronic diseases may be caused by bacteria

• organism/virus capable of causing disease
• damage body tissues -> disease symptoms
• bacteria and viruses that use the human body as a habitat for multiplcation, persistence, and transmission to other hosts

• increased travel
• unvaccinated individuals susceptible to infection
• geriatric population
• HIV/immunocompromised

• beneficial microbes; stay for highly variable periods
• bacteria, fungi

• prevent diseases by competing with pathogens
• stimulate development of immune system response
• aid in digestion

• all cells composed of same elements
• synthesize structures in similar ways
• replicate DNA
• degrade foods via metabolic pathways