Introduction to Microbiology The Microbial World and You

What Are Microorganisms? Minute living things Too small to be seen with the unaided eye Members of several different groups

Different groups of microorganisms bacteria fungi protozoa microscopic algae

Ways that microbes affect us cycling chemicals through our environment serve as the basis of food chains aid normal functioning of animal systems commercial applications cause disease

Chemical elements are cycled by microbes by photosynthesis: C, H, O by chemosynthesis: C, H, N, S, P by aerobic respiration: C, H, O by anaerobic respiration: C, H, N, S, P by fermentation: C, H, O

Basis of food chains phytoplankton (producers) zooplankton (first level of consumers)

Aiding functioning of animal systems aiding in the digestion of ruminants and termites synthesizing B vitamins and vitamin K

Commercial applications of microbes normal synthesis of chemical products food production synthesis of abnormal products

Chemical products normally synthesized by microbes acetone organic acids enzymes alcohols drugs

Foods produced by microbes vinegar sauerkraut pickles alcoholic beverages green olives soy sauce buttermilk cottage cheese cheese yogurt bread sourdough bread

Products of genetically modified microorganisms human insulin and human growth hormone digestive aids cellulose drain cleaner

Some microbes cause disease pathogens (disease-producing microbes) opportunists (microbes that do not normally cause disease, but my do so under certain conditions)

Naming Microorganisms genus name is first and is always capitalized species name (specific epithet) follows the genus name and is never capitalized genus and species names are italicized example: Staphylococcus aureus the cursive indicator of italics is underlining

Family Micrococcaceae Micro- means very tiny Family members are found on human skin Genus Staphylococcus can ferment sugars, and, therefore, can grow with or without oxygen Genus Micrococcus cannot ferment sugars, and, therefore, cannot grow without oxygen

Genus Staphylococcus Staphylo- means clusters of cells coccus- means spherical cells Staphylococcus means clusters of very tiny, spherical cells aureus means golden-colored colonies Staphylococcus aureus means golden- colored colonies of clusters of very tiny, spherical cells

Genus Staphylococcus, continued Staphylococcus aureus: golden-colored colonies S. epidermidis: normal microbe of the skin S. saprophyticus: a microbe that causes decay of organic matter After using the full genus name once in a paragraph, it is then permissible to abbreviate that genus name.

Genus Micrococcus Micrococcus luteus: bright mustard-yellow colonies of clusters of very tiny, spherical cells M. roseus: rose-colored colonies

Classifications of Microorganisms Prokaryotes: cells lack nuclei, membrane- bound organelles, sterols and carbohydrates in membranes Eukaryotes: cells possess nuclei, membrane-bound organelles, sterols and carbohydrates in the membranes

Prokaryotes Bacteria: most of the procaryotes, cell walls contain peptidoglycan and D amino acids, a few bacteria are pathogenic. Archea: may lack cell walls or have unusual cell walls composed of polysaccharides, proteins, and pseudomurein, but never peptidoglycan. Archea are often found in extreme environments.

Bacteria Cell morphology: cocci, bacilli, spirilli, star- shaped, squares Cell arrangement: individual, pairs, chains, tetrads, sarcina (8), (grape-like) clusters Cell walls contain different amounts of peptidoglycan and other substances which result in characteristic staining properties such as Gram-positive, Gram-negative, and Acid-fast cells. Many bacteria are motile by means of flagella Nutritional requirements are extremely diverse

Eukaryotes Algae: photosynthetic unicellular or simple multicellular, mostly aquatic, organisms with cell walls of cellulose Fungi: saprophytic or opportunistic unicellular (yeasts) or simple multicellular organisms with cell walls of chitin Protozoa: unicellular, mostly motile organisms without cell walls, that absorb or ingest nutrients Helminths: parasitic worms: flatworms and roundworms

VIRUSES Living? or Nonliving? Contain a core of one nucleic acid only (either DNA or RNA) Nucleic acid core is surrounded by a protein coat called a capsid Viruses are host-specific: animal, plant, bacterial Some animal viruses possess envelopes