microbio world, evolution, taxonomy, history

microorganisms

organisms that are too small to be seen with the unaided eye

• bacteria

• archaea

• fungi

• protists

• viruses

microbiome

A community of microbes living together in a particular environment

why learn about microbes

• knowledge of microorganisms

• allow humans to

  • prevent food spoilage

  • prevent disease

  • understand and manipulate for use in biotechnology

  • Harness decomposition abilities

three domains of microbiomes

bacteria, archea, eukarya

bacteria

prokaryotes, single-celled, peptidoglycan cell walls, divide by binary fission

• derived nutrition from organic/inorganic chemicals or photosynthesis

• may swim by using moving appendages called flagella

archaea

Prokaryotes lack a peptidoglycan wall

• live in extreme environments

• not known to cause disease in humans directly

fungi

• eukaryotes

• chitian cell wall

• absorb organic chemicals for energy

• Yeasts are unicellular

• Mold and mushroom are multicellular

• sexual or asexual reproduction

protozoa

• eukaryotes

• aborb or ingest organic chemicals

• maybe motile via pseudopods, cilia, or flagella

• free-living or parasitic

• Some are photosynthetic

• reproduce asexually or sexually

virus

• acellular

• consists of DNA or RNA core

• A protein coat surrounds core

• are replicated only when they are in a living host

RNA world hypothesis

1. RNA can store and replicate genetic information; similar structure to DNA

2. RNA can regulate gene expression

3. ribozymes as catalysts for reactions

4. tRNA, mRNA, rRNA

5. ATP

Endosymbiotic theory

• A double membrane system, like bacteria

• organelles like bacteria

• organelles, DNA packaged like bacteria, not nuclear DNA

• transcription/translation machinery, like bacteria

strain

population of organisms that descends from a single organism or pure culture isolate

biovar

differs biochemically physiologically

morphovar

differs morphologically

serovar

differ in antigenic properties

pro of microbes

• chemical products

• fermented foods

• therapeutic agents

• manufacturing

• oxygen with photosynthesis

• decomposers

• fix nitrogen in soil to support plants

cons of microbes

• food spoilage

• disease

• drug resistance

cell theory

All living things are composed of cells

• Robert Hooke: “cell”

anton van leeuenhoek

• “animalcules” viewed through magnifying lenses

• The first microbes were discovered by him

spontaneous generation

life arises from nonliving matter

bigenesis

Living cells arise only from preexisting cells

francesco redi

filled jars with decaying meat

• biogenesis

john needham

boiled nutrients into covered flasks

• spontaneous generation

lazzaro spallanzani

boiled nutrient solution in sealed flasks

• biogenesis

theory of biogenesis

• Virchow proposed that cells arise from preexisting cells

• Louis Pasteur demonstrated that microorganisms are present in the air

pasteurization

• Louis Pasteur: Microbial growth spoils food and beverages

• application of high heat for a short time to kill harmful bacteria in beverages

Miasma theory

• Almost all diseases result from inhaling “bad air”

  • rotting corpses, sweag

• diseases resulting from these poisonous vapors, poor sanitation, unfavorable water, soil conditions, and damp weather

Germ theory

bassi: silkworm disease was caused by fungus

pasteur: disease caused by protozoans

Seemelweis

advocating handwashing to prevent transmission of puerperal fever

lister

used chemical antiseptic (phenol) to precent surgical wound infections

Koch/ Koch’s postulates

demonstrate that a specific microbe causes a specific disease

paul ehrlich

“magic bullet”

• developed a synthetic arsenic drug, salvarsan, to treat syphilis

problems with antimicrobial chemicals

• overuse can lead to resistance

• some drugs can be toxic to humans