Chapter 1 The Microbial World and You

Chapter 1 The Microbial World and You What is Microbiology? Microbes, or microorganisms are minute living things that are usually unable to be viewed with the naked eye. What are some examples of microbes? Bacteria, fungi, protozoa, algae, viruses are examples! Some are pathogenic “Germ” refers to a rapidly growing cell.

Chapter 1 The Microbial World and You What is Microbiology? Microbes: Decompose organic waste Are producers in the ecosystem by photosynthesis Produce industrial chemicals such as ethyl alcohol and acetone Produce fermented foods such as vinegar, cheese, and bread

Chapter 1 The Microbial World and You What is Microbiology?

Chapter 1 The Microbial World and You What is Microbiology? Knowledge of Microbes allows humans to Prevent food spoilage Prevent disease occurrence Led to aseptic techniques to prevent contamination in medicine and in microbiology laboratories.

Chapter 1 The Microbial World and You Microbiology: The study of microorganisms. Microorganisms: Small living organisms that generally can not be seen with the naked eye. Include: uBacteria uFungi (yeasts and molds) uProtozoa uAlgae uMulticellular parasites Also include nonliving infectious agents:  Viruses  Prions

Chapter 1 The Microbial World and You History of Microbiology The first microbes were observed in In 1665, Robert Hooke (Englishman) reported that living things were composed of little boxes or cells.

Chapter 1 The Microbial World and You History of Microbiology , Antoni van Leeuwenhoek (Dutch) described live microorganisms that he observed in teeth scrapings, rain water, and peppercorn infusions.

Chapter 1 The Microbial World and You History of Microbiology Many believed spontaneous generation: life can arise from non-living matter In 1668, the Italian physician Francesco Redi performed an experiment to disprove spontaneous generation. Can you think of an experiment that could disprove spontaneous generation?

Chapter 1 The Microbial World and You History of Microbiology ConditionsResults 3 jars covered with fine net No maggots 3 open jarsMaggots appeared From where did the maggots come? What was the purpose of the sealed jars? Spontaneous generation or biogenesis? Redi filled six jars with decaying meat.

Chapter 1 The Microbial World and You History of Microbiology Rudolf Virchow (German) presented biogenesis: living cells can arise only from preexisting cells.

Chapter 1 The Microbial World and You History of Microbiology So now there are two hypotheses: The hypothesis that living organisms arise from nonliving matter is called spontaneous generation. According to spontaneous generation, a “vital force’ Forms life. The Alternative hypothesis, that the living organisms arise from preexisting life, is called biogenesis.

Chapter 1 The Microbial World and You History of Microbiology 1861: Louis Pasteur demonstrated that microorganisms are present in the air. 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?

Chapter 1 The Microbial World and You History of Microbiology Next experiment, Pasteur’s S-shaped flask kept microbes out but let air in. These experiments form the basis of aseptic technique

Chapter 1 The Microbial World and You History of Microbiology The Golden Age of Microbiology Beginning with Pasteur’s work, discoveries included the relationship between microbes and disease, immunity, and antimicrobial drugs

Chapter 1 The Microbial World and You History of Microbiology Pasteur showed that microbes are responsible for fermentation. Fermentation is the conversation of sugar to alcohol to make beer and wine. Microbial growth is also responsible for spoilage of food. Bacteria that use alcohol and produce acetic acid spoil wine by turning it to vinegar (acetic acid).

Chapter 1 The Microbial World and You History of Microbiology Pasteur demonstrated that these spoilage bacteria could be killed by heat that was not hot enough to evaporate the alcohol in wine. This application of a high heat for a short time is called pasteurization.

Chapter 1 The Microbial World and You History of Microbiology The Germ Theory of Disease 1835: Agostino Bassi showed a silkworm disease was caused by a fungus. 1865: Pasteur believed that another silkworm disease was caused by a protozoan. 1840s: Ignaz Semmelwise advocated handwashing to prevent transmission of puerperal fever from one OB patient to another.

Chapter 1 The Microbial World and You History of Microbiology The Germ Theory of Disease 1860s: Joseph Lister used a chemical disinfectant to prevent surgical wound infections after looking at Pasteur’s work showing microbes are in the air, can spoil food, and cause animal diseases.

Chapter 1 The Microbial World and You History of Microbiology The Germ Theory of Disease 1876: Robert Koch provided proof that a bacterium causes anthrax and provided the experimental steps, Koch’s postulates, used to prove that a specific microbe causes a specific disease. Koch was a physician and Pasteur’s young rival

Chapter 1 The Microbial World and You History of Microbiology Koch's Postulates are used to prove the cause of an infectious disease.

Chapter 1 The Microbial World and You History of Microbiology Koch's Postulates are a sequence of experimental steps to relate a specific microbe to a specific disease.

Koch's research provides a framework for the study of the etiology of any infectious disease. Today, we refer to Koch's experimental requirements as Koch's postulates. They are summarized as follows: 1.The same pathogen must be present in every case of the disease. 2.The pathogen must be isolated from the diseased host and grown in pure culture. 3.The pathogen from the pure culture must cause the disease 4.when it is inoculated into a healthy, susceptible laboratory animal. 5.The pathogen must be isolated from the inoculated animal and must be shown to be the original organism.

Chapter 1 The Microbial World and You History of Microbiology A young milkmaid informed the physician Edward Jenner that she could not get smallpox because she had already been sick from cowpox. 1796: Edward Jenner inoculated a person with cowpox virus. The person was then protected from smallpox. Called vaccination from vacca for cow The protection is called immunity

Chapter 1 The Microbial World and You History of Microbiology What can you say about the cowpox and smallpox viruses?

Chapter 1 The Microbial World and You History of Microbiology Vaccinations produced from avirulent microbial strains produced from live viruses produced from viral particles

Chapter 1 The Microbial World and You History of Microbiology Chemotherapy – treatment with chemicals Chemotherapeutic agents used to treat infectious disease can be synthetic drugs or antibiotics. Antibiotics are chemicals produced by bacteria and fungi that inhibit or kill other microbes. Quinine from tree bark was long used to treat malaria.

Chapter 1 The Microbial World and You History of Microbiology Chemotherapy – treatment with chemicals 1910: Paul Ehrlich developed a synthetic arsenic drug, salvarsan, to treat syphilis. 1930s: Sulfonamides were synthesized.

Chapter 1 The Microbial World and You History of Microbiology 1928: Alexander Fleming discovered the first antibiotic. He observed that Penicillium fungus made an antibiotic, penicillin, that killed S. aureus. 1940s: Penicillin was tested clinically and mass produced.

Chapter 1 The Microbial World and You Modern Developments Bacteriology is the study of bacteria. Mycology is the study of fungi. Parasitology is the study of protozoa and parasitic worms. Recent advances in genomics, the study of an organism’s genes, have provided new tools for classifying microorganisms.

Diversity of Microorganisms I. Bacteria (Sing. Bacterium) u Small, single-celled (unicellular) organisms. u Procaryotes: “Before nucleus”. Lack the following structures: uNuclear membrane around DNA uMembrane bound organelles uMitochondria uChloroplasts uGolgi apparatus uEndoplasmic reticulum uLysosomes

Diversity of Microorganisms I. Bacteria (Sing. Bacterium) u Include two groups: uEubacteria: Peptidoglycan cell walls. uArchaebacteria: Lack peptidoglycan cell walls. u Shapes: Several forms: uBacilli: Rod like. (Sing. Bacillus) uCocci: Spherical. (Sing. Coccus) uSpiral: Corkscrew or curved uSquare uStar shaped

Diversity of Microorganisms I. Bacteria (Sing. Bacterium) u Divide by binary fission (not mitosis). u Source of nutrients varies: uHeterotrophs: Consume organic chemicals. uAutotrophs: Make their own food. Include photosynthetic bacteria. u Motility: Many can “swim” by using moving appendages: uCilia: Small hair like structures uFlagella: Large whip like structures. u Distinguish between motility and Brownian motion.

Diversity of Microorganisms II. Fungi (Sing. Fungus) u Eucaryotes: “True nucleus” uDNA is surrounded by nuclear membrane. uCells have membrane bound organelles: Mitochondria, endoplasmic reticulum, etc. uCells are larger than those of procaryotes. u May be unicellular or multicellular: uUnicellular: Yeasts uMulticellular: Molds, mushrooms u Do not carry out photosynthesis. u Must absorb organic nutrients from their environment.

Diversity of Microorganisms II. Fungi (Sing. Fungus) u Source of nutrients varies: uSaprotrophs: Decomposers that feed on dead and decaying matter. Most fungi are decomposers. uParasites: Obtain nourishment by parasitizing live animals and plants. u Cell wall made of chitin. u May reproduce sexually or asexually.

Diversity of Microorganisms III. Protozoa (Sing. Protozoan) u Eucaryotes: “True nucleus” uDNA is surrounded by nuclear membrane. uCells have membrane bound organelles and are larger than those of procaryotes. u Unicellular u Kingdom Protista u Sexual or asexual reproduction u Classified based on locomotion: uPseudopods: “False feet”. Cytoplasmic extensions. uExample: Amoeba

Diversity of Microorganisms III. Protozoa (Sing. Protozoan) u Classified based on locomotion: uFlagella: Long whip like appendages. uExample: Trichomonas vaginalis, causes trichominiasis, a sexually transmitted disease. uCilia: Small hair like appendages uNonmotile: Do not move in their mature forms. uExample: Plasmodium spp., causative agent of malaria.

Diversity of Microorganisms IV. Algae (Sing. Alga) u Eucaryotes: “True nucleus” u Photosynthetic: Important part of food chain because produce oxygen and carbohydrates used by animals. u Unicellular or multicellular u Kingdom Protista u Sexual or asexual reproduction u Cell walls composed of cellulose u Found in aquatic environments (oceans, lakes, rivers), soil, and in association with plants.

Diversity of Microorganisms V. Viruses u Acellular infectious agents, not considered living because they lack cells. u Obligate intracellular parasites: Viruses can only reproduce by using the cellular machinery of other organisms. u Simple structure: uProtein coat (capsid) with either DNA or RNA, but not both. uMay also have a lipid envelope.

Diversity of Microorganisms VI. Multicellular Animal Parasites u Eucaryotes: “True nucleus” u Multicellular animals, usually are visible to the naked eye. u Microscopic during some stages of life cycle. u Spend part or all of their lives inside an animal host. u Helminths include: uFlatworms (Platyhelminths): E.g. Tapeworm uRoundworms (Nematodes): E.g. Ascaris, pinworm.