MICROBIOLOGY

Introduction & Classification

Topics

• Classification

• Methods of Microbiology

• Nutrition & Growth

• Microbial Structure

• Metabolism

• Host parasite relationships

• Control of Growth

Types of Microorganisms

• Bacteria– Gram positive & gram negative

• Viruses– RNA & DNA

• Fungi– Yeasts & molds

• Protozoa

History

• Robert Hooke– Described units in cork as cells

Anton van Leeuwenhoek-1667– Made lenses or simple microscopes

Spontaneous Generation

• Abiogenesis-living matter arising from nonliving matter

• Redi –maggots & meat

• Pasteur et al disproved abiogenesis

Pasteur

• Fermentation– Yeast ferment grape juice –alcohol– Bacteria ferment grape juice-acids

• Pasteurization

Germ Theory of Disease

• Koch– Koch’s postulates

– Developed pure culture techniques

– Discovered TB agent

Immunology/Chemotherapy

• Jenner and smallpox vaccine– Used cowpox virus

Antiseptics

• Semmelweis

• Lister

Fleming

• Discovered penicillin

Taxonomy

• System of cataloging organisms– Identification: characterization of organisms

– Classification: arrangement of organisms into similar groups

– Nomenclature: assign names

Binominal Nomenclature

• Genus-capitalized ; collection of species

• Microbes – species can be subdivided into strains

• Strains have small genetic differences

Rules

• Both genus & species underlined or italicized

• Strain-subdivision of species– ID by name, number or letter– Example- Escherichia coli- E. coli K12

Classification

• Wittaker-5 kingdoms– Plants– Animals– Fungi– Protista– Monera or Prokaryote

Domains

• Carl Woese-1980s

• Based upon modern techniques– Sequence of rRNA in ribosomes

• Three cell types based upon ribosomes

Three Domains

• Domains above kingdom level

• Bacteria or Eubacteriae– Prokaryotes with peptidoglycan in cell wall– Divide by binary fission– Motile by flagella or cilia– Sensitive to antibiotics

Archaea

• Ancient prokaryotes– Cell wall present, not peptidoglycan

– Live in extreme environments

– Have unusual metabolic processes

– Not sensitive to antibiotics

Archaea

• Methanogens -strict anaerobes– Produce methane from CO2 + H2

– Live in anaerobic mud lakes

– Intestine of cows

Archaea

• Halophiles– Require high concentration of salt

• Maintain cell wall

– Spoilage of food-salted fish

– Salt lakes

Archaea

• Thermophiles– Live in hot sulfurous waters or acidic water

– Nucleic acids/proteins do not function at low temperatures

– Volcanic vents in ocean

Eukarya

• All eukaryotes

• Cell wall varies in composition

• Not sensitive to antibiotics

• Fungi-yeasts and molds

• Protists-slime molds, protozoa, & algae

• Plants & animals

Endosymbiotic Theory

• Eukaryotes evolved from prokaryotes

• Supported by similarities between prokaryotes & organelles in eukaryotes

• Mitochondria & chloroplasts same size as prokaryote cell– Contain DNA, 70S ribosomes

• Endosymbiont-organism that lives within another

Support for Theory

» Prokary Eukary Mitoch & Chloro

• DNA circular linear circular

• Histones No Yes No

• Ribosomes 70S 80S 70S

• Growth binary mitosis binary

• Cyanophora

Viruses

• Obligate intracellular parasites

• Not cells so non living agent

• No ribosomes

• Classification is different

Viroids & Prions

• Viroids– Single short piece of RNA– Cause disease in plants – ? In humans

• Prions– Protein– Cause neurodegenerate diseases– Humans & animals– CJD & mad cow

New Challenges

• Antibiotic resistance– MRSA, VRE & ESBL

• Emerging diseases– SARS & Avian Influenza

• Bioterrorism– Anthrax, smallpox, plague, botulism