The Microbial World and You

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? Microbes everywhere on your body 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

Did you know? 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?

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) Systematics: the science oforganizing organisms into groups. Phylogenetics: ascertaining evolutionary relationships between organisms. Taxonomy: science of classifying organisms.

Look at the background! 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

How are prokaryotes classified? Divides prokaryotes into (based on rRNA sequences) Bacteria Archaea

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

What are the key differences between the three domains? Archaea Bacteria Eukarya 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 Virus, viroids and prions Why not? Viral species: population of viruses with similar characteristics

A closer look at the microbes

What are bacteria? Simple, single-celled 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 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

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