The Microbial World and You

 Microorganisms  too small to be seen with unaided eye  “Germ”  rapidly growing cell

What are microbes?  Fungi (molds, yeasts)  mycology  Protozoa  parasitology  Microscopic algae  phycology

What do they do?  Decompose  organic waste  Producers in the ecosystem  by photosynthesis  Produce industrial chemicals  Ethanol and acetone  Produce fermented foods  vinegar, cheese, and bread  Produce manufacturing products  (e.g., cellulase) and treatment (e.g., insulin)  A few are pathogenic,  disease-causing Microbes everywhere on your body Microbes— Lactobacillius acidophilus —make yogurt Others make beer and wine— Saccharaomyces cereviceae

The better question might be, “what don’t they do?”  Allows humans to  Prevent food spoilage  Prevent disease occurrence  Led to aseptic techniques to prevent contamination in medicine and in microbiology laboratories

 Bacteria causes body odor  Bacteria, tiny as they are, can get sick, too!  Under the right conditions a bacterium like Escherichia coli can grow from just one cell to 1 million cells in less than 7 hours!  How their size compares? Did you know?

How are microbes named and classified?  Linnaeus established  system of scientific nomenclature.  Each organism has two names:  genus and specific epithet.  Are italicized or underlined. The genus is capitalized and the specific epithet is lower case.  Are “Latinized” and used worldwide.  May be descriptive or honor a scientist.

Scientific Names  Staphylococcus aureus  Describes the clustered arrangement of the cells (staphylo-) and the golden color of the colonies (aur-).  Escherichia coli  Honors the discoverer, Theodor Escherich, and describes the bacterium’s habitat–the large intestine or colon

Taxonomy

What is systematics?  Study of phylogenetic relationships  Phylogenetics = ________  Taxonomy = __________  Also a way of organizing/ classifying  Taxa (taxon— singular)

 Plant and Animal Kingdoms  Bacteria and fungi  put in the Plant Kingdom  Kingdom Protista proposed  for bacteria, protozoa, algae, and fungi  Prokaryote introduced for cells "without a nucleus“  Prokaryote defined as cells in which nucleoplasm is not surrounded by a nuclear membrane  Kingdom Fungi  Kingdom Prokaryotae proposed  Two types of prokaryotic cells found Look at the background!

How are prokaryotes classified?  Use Bergey’s Manual of Systemic Bacteriology  Divides prokaryotes into (based on rRNA sequences)  Bacteria  Archaea

Who is Carl Woese? 1978: created current classification scheme  Three domains  Bacteria  Archaea  Eukarya  Protists  Fungi  Plants  Animals

What are the key differences between the three divisions? EukaryotesProkaryotesArchaea Cell type Cell wall Organelles/ nucleus? Sensitive to antibiotic?

What is the taxonomy of organisms?  Domain  Kingdom  Phylum  Class  Order  Family  Genus  Species

How are eukaryotes classified?  Endosymbiotic theory  Numerous kingdoms, including  Protista  Fungi  Plantae  Animalia

What about viruses—How are they classified?  Not included in three domains, which are _______ _______ and ______  Why not?  Viral species: population of viruses with similar characteristics

How do I tell prokaryotes apart?  Really difficult  Morphology is very similar! B. anthracisB. japonicum

So how can we tell them apart?  Lab techniques such as  Staining  Gram positive vs. Gram negative

 Biochemical test  Different bacteria will grow on different types of media  Carbohydrates  Proteins  Serology  Slide agglutination test  Look for clumping of bacteria with antiserum  Serotypes are strains with different antigens  DNA fingerprinting  rRNA sequencing So how can we tell them apart?

A closer look at the microbes

What are bacteria?  Simple, single- celled  ubiquitous  Prokaryotes  DNA is not inside a membrane  Come in different shapes  Coccus (cocci, plural)  Bacillus (bacilli, plural)  Spiral (corkscrew, comma or curved)  Peptidoglycan cell wall  Binary fission  Some have flagella

What are archaea?  Also prokaryotes  Cells wall do not have peptidoglycan  Live in extreme conditions  Extreme halophiles  Hyperthermophiles  Methanogens  Not pathogenic Figure 4.5b

What are fungi?  Eukaryotes  Have a true nucleus  More closely related to __________  wall of chitin  Uni- and multicellular  Includes  Molds  Mushrooms  Yeasts  Slime molds  Sexual and asexual reproduction Figure 1.1b

What are protozoa?  Eukaryotes  Absorb or ingest organic chemicals  May be motile via pseudopods, cilia, or flagella Figure 1.1c

What are algae?  Eukaryotes  Cellulose cell walls  Use photosynthesis for energy  Produce molecular oxygen and organic compounds Figure 1.1d

What are viruses?  Acellular  Consist of DNA or RNA core  Core is surrounded by a protein coat.  Coat may be enclosed in a lipid envelope.  Viruses are replicated only when they are in a living host cell. Figure 1.1e

What are multicellular animal parasites?  Eukaryote  Multicellular animals  Parasitic flatworms and round worms are called helminths.  Microscopic stages in life cycles. Figure 12.28a

Brief History of Microbiology

The First Observations  Ancestors of bacteria were  first life on Earth.  observed in  1665, Robert Hooke reported  living things were composed of little boxes or cells.  1858, Rudolf Virchow  cells arise from preexisting cells.  Cell theory: All living things are composed of cells and come from preexisting cells.

How did we discover microbes?  Before the microscope:  Spontaneous generation  “vital force” forms life.  Microscope  Van Leeuwenhoeke, 1670s  Louis Pasteur, 1861  Showed microorganisms are in the air  Refutes spontaneous generation with biogenesis  Used curved flask ConditionsResults Nutrient broth placed in flask, heated, not sealed Microbial growth Nutrient broth placed in flask, heated, then sealed No microbial growth Spontaneous generation or biogenesis?

When was the golden age of microbiology?   Pasteurization  Developed after investigation of fermentation  Demonstration of aseptic technique  microbes are responsible for fermentation.  Fermentation  conversion of sugar to alcohol to make beer and wine.  Microbial growth  responsible for spoilage of food.  Pasteur demonstrated  spoilage bacteria killed by heat  Pasteruization  high heat for a short time.

The Germ Theory of Disease  Joseph Lister, 1860s used a chemical disinfectant to prevent surgical wound infections  Germ theory of disease  Robert Koch, 1876, Germany  Bacillus anthracis causes anthrax  provided the experimental steps  Vaccination  Edward Jenner, 1796  Small pox and cow pox  Immunology

What about modern microbiology?  1928: Alexander Fleming  first antibiotic.  Penicillium fungus made  antibiotic, penicillin, that killed S. aureus.  1940s: Penicillin was tested clinically and mass produced. Figure 1.5

Some terms in microbiology  Bacteriology is the study of bacteria.  Mycology is the study of fungi.  Parasitology is the study of protozoa and parasitic worms.  Immunology is the study of immunity. Vaccines and interferons are being investigated to prevent and cure viral diseases  Virology is the study of viruses.

Some modern concepts  Bioremediation  degrade organic matter in sewage.  degrade or detoxify pollutants such as oil and mercury.  Biological Insecticides  Biotechnology  Genetic engineering UN 2.1

What is normal microbiota?  Normal microbiota prevent growth of pathogens.  Normal microbiota produce growth factors such as folic acid and vitamin K.  Resistance is the ability of the body to ward off disease.  Resistance factors include skin, stomach acid, and antimicrobial chemicals.

What are infectious diseases?  When a pathogen overcomes the host’s resistance, disease results.  Emerging infectious diseases (EID): New diseases and diseases increasing in incidence.  West Nile Virus  Bovine spongiform encephalopathy  Ebola hemorrhagic fever  Hantavirus  AIDS  Anthrax