Microbiology – a revisit study of organisms too small to be seen by the naked eye. Microbes or Microorganisms include bacteria, viruses, fungi, algae, protozoa etc. Prions (“infectious proteins”) are recent addition.

Specializations in Microbiology Epidemiology and Public Health Microbiology distribution and spread of diseases and their control and prevention Food Microbiology use of microbes in the production of food products and drinks Agricultural and Veterinary Microbiology use of microbes to increase crop and livestock yield and control of plant pests and animal diseases Environmental Microbiology study of the beneficial and harmful effects of microbes on the environment

Beneficial Uses of Microbes Synthesis of drugs, hormones and enzymes

Beneficial Uses of Microbes Bioremediation is the use of microbes to degrade organic matter in sewage and detoxify pollutants such as oil spills.

Modern Uses of Microbes Biotechnology, the use of microbes as miniature biochemical factories to produce food, drugs, energy..etc Genetic engineering makes use of molecular biology and recombinant DNA techniques as new tools for biotechnology. Gene therapy replaces missing or defective genes in human cells through genetic engineering. Genetically modified bacteria are used to protect crops from pests and freezing.

Woese-Fox 3 Domain System Microbial Taxonomy Woese-Fox 3 Domain System

General Characteristics Prokaryotes no nucleus and organelles Eukaryotes membrane bound nucleus and organelles

Scientific Names Staphylococcus aureus describes clustered arrangement of cells and golden yellow color of colonies Escherichia coli Honors the discoverer, Theodor Escherich and describes its habitat, the colon. After the first use, scientific names may be abbreviated with the first letter of the genus and full species epithet. (Ex: E. coli)

Comparative cellular structures of microbes Cell Types Comparative cellular structures of microbes

The Microbes viruses protozoa bacteria bacteriophage algae cyanobacteria spirochaetes fungi

Size of Microbes Microbes vary in size ranging from 10 nm (nanometers) to 100 mu (micrometers) to the macroscopic. Viruses in nm = 10-9 m (meter) Bacteria in um = 10-6 m Helminths in mm = 10-3 m

Bacteria Prokaryotes Peptidoglycan cell walls Ex: Escherichia coli

Archaea Prokaryotes Lack peptidoglycan Live in extreme environments (extremophiles) Include: Methanogens Extreme halophiles Extreme thermophiles

Fungi Eukaryotes Chitin cell walls Molds and mushrooms are multicellular Yeasts are unicellular

Protozoa Eukaryotes Mostly saprobes and commensals May be motile by means of pseudopod, cilia or flagella

Algae Eukaryotes Cellulose cell walls Photosynthetic Produce molecular oxygen and organic compounds Part of food chain

Helminths Eukaryotes Multicellular animals Parasitic flatworms and roundworms called helminths Microscopic stages in life cycles

Viruses Acellular Genome consist of DNA or RNA called Core Core surrounded by protein coat called Capsid Virion may be enclosed in lipid envelope

Prions Proteinaceous infectious agents Causes Bovine Spongiform Encephalopathy (BSE) Also causes Creutzfeldt-Jacob Disease (CJD) An Emerging Infectious Disease (EID)

Microbial Diversity Microbial diversity encompasses the spectrum of variability among all types of microorganisms in the natural world and as altered by human intervention. Microorganisms are essential for the earth to function. They play many roles both on land and in water, including being the first to colonize and improved effects of naturally occurring and man-made disturbed environments.

Microbial Diversity Because microorganisms are small, they are least known, and this gap in knowledge is particularly apparent for bacteria and other procaryotic organisms. Current evidence suggests there exists perhaps 300,000 to 1 million species of procaryotes on earth yet only 3,100 bacteria are described in Bergey's Manual. Learning more about these microorganisms will be of value for the following reasons:

Microbial Diversity Microorganisms are important sources of knowledge about the strategies and limits of life, Microorganisms are of critical importance to the sustainability of life on our planet, The untapped diversity of microorganisms is a resource for new genes and organisms of value to biotechnology, Diversity patterns of microorganisms can be used for monitoring and predicting environmental change, Microorganisms play a role in conservation and restoration biology of higher organisms, and Microbial communities are excellent models for understanding biological interactions and evolutionary history.

Microbial Diversity Factors governing microbial diversity Abiotic factors – ?? Biotic factors – ??