Chapter 1 The Microbial World and You

Vocabulary People Microbiology an Introduction Microbes in Our Lives • Microorganisms are organisms that are too small to be seen with the unaided eye • Microbes include bacteria, fungi, protozoa, microscopic algae, and viruses also worms Chapter 1 The Microbial World and You Germ refers to a rapidly growing cell 1 2 Microbes in Our Lives Microbes in Our Lives • A few are pathogenic (disease-producing) • Knowledge of microorganisms allows humans to – Prevent food spoilage – Prevent disease – Understand causes and transmission of disease to prevent epidemics • Decompose organic waste • Generate oxygen by photosynthesis • Produce chemical products such as ethanol, acetone, and vitamins • Produce fermented foods such as vinegar, cheese, and bread Led to aseptic techniques to prevent contamination in medicine & in microbiology laboratories • Produce products used in manufacturing (e.g., cellulose) and disease treatment (e.g., insulin) 3 1914 – Chaim Weizmann, a Russian-born chemist working in England discovered the process of using microbes to produce acetone & butanol, which became important 4 1 The Microbiome The Microbiome • An adult human is composed of 30 trillion body cells – Harbors another 40 trillion bacterial cells • Normal microbiota is the collection of acquired microorganisms on or in a healthy human being – Begin to be acquired as newborns – May colonize the body indefinitely – May colonize the body fleetingly (making them transient microbiota) present for short time wo causing • The microbiome is a group of microbes that live stably on/in the human body – Help to maintain good health – Can prevent growth of pathogenic microbes – May help train the immune system to discriminate threats 5 Bacteria in the intestines aid digestion & synthesize some vitamins like vitamin B for metabolism & vitamin K for blood clotting disease • Colonization can only occur at body sites that provide nutrients and the right environment for the microbes to flourish 6 Factors that influence what types of microbes can flourish: temp, Ph, & presence/absence of chemical compounds Naming and Classifying Microorganisms Normal Microbiota • Normal microbiota prevent growth of pathogens • Carolus Linnaeus established the system of scientific nomenclature in 1735 • Normal microbiota produce growth factors such as vitamins B and K Each organism has 2 names: the genus & the specific epithet • Resistance is the ability of the body to ward off disease • Resistance factors include skin, stomach acid, and antimicrobial chemicals 7 8 2 Nomenclature Nomenclature • Scientific names – Are italicized or underlined ▪ The genus is capitalized; the specific epithet is lowercase – Are “Latinized” and used worldwide – May be descriptive or honor a scientist • Escherichia coli – Honors the discoverer, Theodor Escherich – Describes the bacterium's habitat—the large intestine, or colon 9 10 Nomenclature Nomenclature • Staphylococcus aureus – Describes the clustered (staphylo-) spherical (coccus) cells – Describes the gold-colored (aureus) colonies • After the first use, scientific names may be abbreviated with the first letter of the genus and the specific epithet: – Escherichia coli and Staphylococcus aureus are found in the human body – E. coli is found in the large intestine, and S. aureus is on skin A bacterium commonly found on human skin 11 12 3 genetic material isn't enclosed in a special nuclear membrane Types of Microorganisms Bacteria • Bacteria • Prokaryotes (bacteria & archaea) – “Prenucleus” • Archaea • Single-celled (unicellular) • Fungi • Peptidoglycan cell walls • Protozoa • Divide via binary fission • Algae Derive nutrition from organic chemicals (dead/living animals), photosynthesis, or from inorganic substances • Viruses • Multicellular Animal Parasites 13 • May “swim” by using moving appendages called flagella 14 Individual bacteria may form pairs, chains, clusters, or other groupings Are enclosed in cell walls that are largely composed of a carbohydrate & protein complex Several shapes: Bacillus, Coccus, & Spiral; Star-shaped or square Sporangia Archaea Fungi • Are prokaryotes • Eukaryotes – Distinct nucleus surrounding DNA • Lack peptidoglycan cell walls – May lack cell wall entirely • Chitin cell walls • Often live in extreme environments • Absorb organic chemicals for energy • Include: produce methane as a waste product – Methanogens from respiration – Extreme halophiles live in extremely salty environments – Extreme thermophiles live in hot sulfurous water • Yeasts are unicellular • Molds and mushrooms are multicellular Consists of masses of mycelia, which are composed of filaments called hyphae Generally do not cause disease in humans 15 16 4