The Golden Age of Microbiology
The Golden Age of Microbiology Bio 229
Santa Ana College
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This 14 page Class Notes was uploaded by Study_Smarter_Now on Sunday September 25, 2016. The Class Notes belongs to Bio 229 at Santa Ana College taught by Ou, M in Fall 2016. Since its upload, it has received 9 views. For similar materials see General Microbiology in Biology at Santa Ana College.
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Date Created: 09/25/16
THE GOLDEN AGE OF MICROBIOLOGY: BENEFICIAL MICROBES: Bread, wine and beer • One that has a greater impact or culture and society than that of any disease or epidemic - was domestication of the yeast used by bakers and Brewers. It's name , Saccharomyces cerevisiae meaning "sugar fungus [that makes] beer" • Scientist use yeast to delve into mysteries of cellular function, organization, and genetics, making Saccharomyces the most intently studied eukaryotes. 1.6 List and answer 4 questions that propelled research in what is called the "Golden Age of Microbiology." 1: Is spontaneous generation of microbial life possible? No, Louis Pasteur showed that broth only became cloudy with bacteria when exposed to bacteria, not just air, using swan neck ﬂasks to trap bacteria. 2: What causes fermentation? Louis Pasteur conducted experiments that showed microorganisms caused fermentation of grape juice, not air. Observed yeast cells arising from other yeast cells, showing that life comes from life. He discovered the ability of yeast to ferment grape juice both in the presence and absence of oxygen & he developed a method of heating grape juice to preserve ﬂavor, but prevent fermentation (pasteurization) 3: What causes disease? Pasteur's ﬁndings that life arises from life gave rise to the germ theory of disease in which pathogens (speciﬁc germs) are responsible for diseases. Robert Koch developed the 4 principles to guide scientists in isolating a disease causing pathogen. 4: How can we prevent infection and diseases? Ignaz Semmelweis ﬁrst to notice correlation between hand washing with chlorinated I me water and a decried incidence of infection. Joseph Lister instituted sterilization of wounds with a phenol Florence Nightingale pioneered for sanitary conditions in hospital wards, including removing dirty clothes of patients to remove sources of infection. John Snow noticed need for clean water and adequate sewage treatment to stop outbreaks of Cholera. Edward Jenner created vaccination to prevent the spread of diseases by injecting small particles of the virus into people to create an immune response. DOES MICROBIAL LIFE SPONTANEOUSLY GENERATE? ✦ Many philosophers and scientists of past ages thought that living things arose via 3 Processes: 1: Through asexual reproduction 2: Through sexual reproduction 3: from nonliving matter Abiogenesis (spontaneous generation): The rise of living things from nonliving matter ¹ a = not ¹ bio = life ¹ genein = to produce Redi's Experiements • Italian physician Francesco Reid demonstrated by a series of experiments that when decaying meat was kept isolated from ﬂies, maggots never developed, whereas meet exposed to ﬂies was soon infested. - Begin to doubt Aristotle's theory and adopt the view that animals come only from other animals. Needham's Experiments: • Boiled beef gravy and infusion of plant material in vials, which he then tightly sealed with corks. Some days later, Needham observed that the vials were cloudy, and examination revealed an abundance of "microscopical animals of most dimensions" as he explained it there must be a "life force" that caused inanimate matter to spontaneously come to life b/c he had heated the vial suﬃciently to kill everything. ¹ Infusions are broths made by heating water containing plant or animal material. Spallanzani's Experiments: • Boiled infusion for almost an hour and sealed the vials by melting their slender news closed. • His infusion remained clear unless he broke the seal and exposed the infusion to air, after which they became cloudy with microorganisms. • He concluded 3 things: - Needham either had failed to heat his vials suﬃciently to kill all microbes or had not sealed the mightily enough. - Microorganisms exist in the air and can contaminate experiments - Spontaneous generation of microorganisms does not occur all living things arise from other living things. Pasteur's Experiments: • Demonstrated spontaneous generation did not exist • Boiled infusion long enough to kill everything. But instead of sealing the ﬂasks, he bend their necks into an S-shape, which allowed air to enter while preventing the introduction of dust and microbes into the broth. • Reported that his "swan-necked ﬂasks" remained free of microbes even 18 months later. - b/c the ﬂasks contained all the nutrients (including air) known to be required by living things, he concluded: "Never will spontaneous generation recover from the mortal blow of this simple experiment" • He broke the necks oﬀ some ﬂasks, exposing the liquid in them directly to the air, and he carefully tilted others so that the liquid touches the dust that had accumulated in their necks. - The next day, all of these ﬂasks were cloudy with microbes. - concluded that the microbes in the liquid were the progeny of microbes that had been on the dust particles in the air. The Scientiﬁc Method: The Scientiﬁc Method: Provides a framework for conducting an investigation rather. Than a rigid set of speciﬁc "rules" consisting of 4 basic steps: 1: A group of observations lead a scientist to ask a question about some phenomenon. 2: The scientist generates a hypothesis - that is, a potential answer to the question. 3: The scientist designs and conducts an experiment to test the hypothesis 4: Based on the observed results of the experiment, the scientist either accepts, rechecks or modiﬁes the hypothesis. The scientist then returns to earlier steps in the method, either modifying hypotheses and then testing them or repeatedly testing accepted hypotheses until the evidence for a hypothesis is convincing. Theories / Laws: Accepted hypotheses that explains many observation and are repeatedly veriﬁed by numerous scientists over many years. • To accept experiments (& their results) as valid: They must include appropriate control groups - groups that are treated exactly the same as the other groups in the experiment except for the one variable that the experiment is designed to test. • In Pasteur's experiments on spontaneous generation, what is his control groups? His "control ﬂasks" we're the sterile infusion composed of all the nutrients living things need as well as air made available through the ﬂasks' "swan neck" His "experimental task" for testing his hypothesis were exposed to exactly the same conditions + contact with the dust in the vend in the neck. (B/c exposure to the dust was the only diﬀerence between the control and experimental groups, Pasteur was able to conclude that the microbes growing in the infusion arrived from the dust particles) 1.7 Identify the scientist who argued in favor of spontaneous generation. Aristotle & John T. Needham said that microbes spontaneously generated. 1.8 Compare and contrast the investigation of Reid, Needham, Spallanzani, and Pasteur concerning spontaneous generation. Francisco Redi: Developed experiments to detect whether ﬂies arose from rotting meat, or from ﬂies themselves. Used 3 jars, each with a piece of meat inside. One open to air, one sealed, and another overhead with gauze. Open jar developed ﬁles, second no ﬂies, 3rd no ﬂies neither. Demo that ﬂies arose from neither the air nor meat. John Needham: Disagreed with Redi. Boiled beef grey and infusion of plant material and slewed the vials with corks. Samples became cloudy. Concluded there must be a life force cratering bacteria. (Did not seal vials completely and did not account for bacteria existing in the corks themselves. Did not have control vial that was exposed to air, but not bacteria) Lorenzo Spallanzani: Boiled infusion for much longer and sealed them by melting the vial necks closed. Infusion remained clear unless exposed to air. Only proved broth did not creat bacteria Louis Pasteur: Used a goose neck ﬂask to test whether air can create life. Boiled the infusion in the bottom of the ﬂask. The neck allowed air to move in and out, but trap dust and microbes in the bend neck. Infusion remained clear with no bacteria. Showed that air can be in contact with the broth, but not cause the appearance of bacteria. 1.9 List 4 steps in the scientiﬁc method of investigation Step 1: The scientist collects observations that lead to question about a phenomenon. Careful observations are documented and analyzed. Step 2: Generates hypothesis, or educated guess about the answer to the question. Use background info. And info gathered during observations. Step 3: Design experiments to test hypothesis. (Highly secured experiments and only test one variable at a time) Step 4: If hypothesis is rejected, revisit observations and question from step 1 to create another hypothesis. Repeats experiments, changing only one variable at a time until a hypothesis is uprooted by the results. WHAT CAUSES FERMENTATION? Pasteur's Experiment • Discovered that yeast are facultative anaerobes Facultative Anaerobes: organisms that can live with or without oxygen. ¹ an = not ¹ are = air ¹ bios = life • Pasteur developed pasteurization Pasteurization: A process of heating the grape juice just enough to ill most contaminating bacteria without changing the juice's basic qualities so that it could then be inoculated with yeast to ensure that alcohol fermentation occurred. Industrial Microbiology (biotechnology): Microbes are intentionally used to manufacture products. • B/c of his many, varied, and signiﬁcant accomplishments in working with microbes, Pasteur may be considered the Father of Microbiology. 1.10 Discuss the signiﬁcance of Pasteur's fermentation experiments to our world today. Shows that yeast could ferment the sugars in grape juice with or without oxygen. He observed yeast budding, or reproducing in samples of grape juice under microscope. Further discovered bacteria can also ferment grape juice producing acid. Lead him to develop a process of sterilizing drinks / food that is still used today (pasteurization). Juices are heated to the right temperature to kill bacteria. But doesn't change the juice's basic qualities. 1.11 Explain why Pasteur may be considered the Father of Microbiology His experiments with bacteria in the gooseneck ﬂask provided crucial evidence to disprove the theory of spontaneous generation. Disproved the theory that air had a life force. Discovered fermentation was possible without air, and was caused by yeast. Developed the process of pasteurization, which is used to preserve food and drink and create Alcohol. Developed the germ theory that bacteria can cause human disease (Pathogens). 1.12 Identify the scientist whose experiments lead to the ﬁeld of biochemistry and the study of metabolism. Eduard Buchner investigated the chemical cause of fermentation. (A metabolic process the converts sugar to acid or alcohols) Found tiny proteins (enzymes) that were responsible for fermentation. Showed that fermentation does not require living cells. WHAT CAUSES DISEASE? Germ Theory of Disease: The theory that microorganisms are responsible for disease. (B/c a particular disease is typically accompanied by the same symptom in all aﬀected individuals) Pathogen: A bacterium, virus, or other microorganism that causes disease ¹ pathos = disease ¹ genein = to produce Etiology: The cause, set of causes, or manner of causation of a disease or condition. Koch's Experiments • Koch carefully examined the blood of infected animals, and in every case he identiﬁed a rod-shaped bacterium that formed chains. - Observed the formation of resting stages (endoscopes) within the bacterial cells and showed that the endoscopes always produced anthrax when they were injected into mice. • Most bacteria are very small, and diﬀerent types exhibit few or no visible diﬀerences. • He solved the problem by taking specimens (blood, pus, sputum) from disease victims and then spearing the specimens onto a solid surface such as a slice of potato or a gelatin medium. - Then waited for bacteria and fungi present in the specimen to multiply and form distinct colonies - hypothesized that each colony consisted of the progeny of a single cell. - Inoculated samples from each colony into laboratory animals to see which caused disease. • Koch and his colleagues are also responsible for many other advances in laboratory microbiology, including the following: - simple staining techniques for bacterial cells and ﬂagella - the ﬁrst photo micrograph of bacteria - the ﬁrst photograph of bacteria in diseased tissue - Techniques for estimating then number of bacteria in a solution based on the number of colonies that form after inoculation onto a solid surface - the use of steam to sterilize growth media - The use of Petri dishes to hold solid growth media - Laboratory techniques such as transferring bacteria between media using a metal wire that has been heat-sterilized in a ﬂame - Elucidation of bacteria as distinct species. Koch's Postulates Koch's Postulates A series of steps that must be taken to prove the cause of any infectious disease 1: The suspected causative agent must be found in every case of the disease and be absent from healthy hosts. 2: The agent must be isolated and grown outside of the host. 3: When the agent is introduced to a healthy, susceptible host, the host must get the disease. 4: The same agent must be found in the diseased experimental host • use the term suspected causative agent b/c It is merely "suspected" until the postulates have been fulﬁlled. Gram's Stain • Danish scientist Christian Gram's procedure involved the application of a series of dyes, leaving some microbes purple and other pink. - We now label the ﬁrst group of cells gram positive (purple cells) and gram negative (pink cells). 1.13 List at least 7 contributions made by Koch to the ﬁeld of microbiology 1: Koch developed Koch's Postulates, which were used to ID a disease-causing agent. 2: Created simple staining techniques for bacteria that allowed scientists to view the colorless bacteria under a microscope. 3: Took the ﬁrst photograph of bacteria in healthy and diseased tissue, helping the ID bacteria as the disease causing agent in infections. 4: Used steam for sterilization to prevent infection 5: developed techniques for estimating the number of bacteria in solution based on the number of colonies that form on a surface after colonization. Helped ID the arterial during infection. 6: Used Petri dishes with solid media to culture bacteria 7: ID bacteria as individual species 8: Developed laboratory techniques to transfer bacteria between media using a metal wire sterilized by that (by sterilizing metal wire, eliminated outside contaminants so he could grow speciﬁc bacteria in the lab) 1.14 List the 4 steps that must be taken to prove the cause of an infectious disease. 1: The disease causing agent must be found in all patients and hot healthy individuals 2: The agent must be able to be isolated and grown in the lab 3: When the agent is introduced to a healthy subject, it must cause the same disease. 4: The agent must be able to be isolated from the newly infected subjects. 1.15 Describe the contribution of Gram to the ﬁeld of microbiology. Developed a more complicated staining technique called gram stain. Gram staining involves using diﬀerent dyes in order to stain microbes purple or pink depending on the truck urge of their cell wall. Cells that have a thick cell wall stain purple and are considered gram positive. Cells that have a thin cell wall with layers of lipids outside stain pink and are considered gram negative. Gram negative bacteria can cause serious infections in humans. HOW CAN WE PREVENT INFECTION AND DISEASE? Clinical Case Study: • The cit had an unusually wet spring, which left behind swamps and stagnant pools that became breeding grounds for mosquitoes. • In late August 1793, a female Aedes aegypti mosquito bit an infected refugee and then bit a healthy Philadelphian. This began a yellow fever epidemic that killed 10% of the city's population within 3 months ad forced another 30% to ﬂee for their lives. Victims suﬀered from high fever, nausea, skin eruptions, black vomit, and jaundice. Question: 1: People who left the city seemed to have milder causes of yellow ever or avoided the infection altogether. Explain why. Mosquitos are the vectors (carrier) of the yellow fever virus, Mosquitos live in stagnant pools of water which were common in Philadelphia due to wet spring. People who moved away from the area were less exposed to the vector less likely to be infected. 2: The story mentions that the coming of the ﬁrst frost brought an end to the epidemic. Discuss the possible reasons why this would provide at least temporary relief from the epidemic. This would provide temporary relief from the epidemic b/c since mosquitos are carriers, they become dormant during the winter and don't bite people are not spreading the virus. Semmelweis and Handwashing • Semmelweis hypothesized that medical students carried "cadaver particles" from their autopsy studies into the delivery rooms and that these "particles" resulted in puerperal fever. • Gain support of his hypothesis when a doctor. Who sliced his ﬁnger during an autopsy died after showing symptoms similar to those of puerperal fever. • Today we know that the primary cause of puerperal fever is a bacterium in the genus Streptococcus which is usually harmless on the skin or in the mouth but causes severe complications when it enter the blood. • Semmelweis be gain requiring medical students to wash their hands with chlorinated lime water, a substance long used to eliminate the smell of cadavers. - Mortality in the subsequent year dropped from 18.3 - 1.3% Lister's Antiseptic Technique • Joseph Lister modiﬁed and advanced the idea of antisepsis in health care settings. • He began spraying wounds, surgical incisions, and dressings with carbolic acid (phenol), a chemical that had previously proven eﬀective in reducing odor and decay in sewage. • Lister became the founder of antiseptic surgery and opened new ﬁelds of research antisepsis and disinfection. Nightingale and Nursing • Florence Nightingale was a dedicated English nurse who introduced cleanliness and other antiseptic techniques into nursing practice. • After the war, Nightingale returned to England, where she actively exerted political pressure to reform hospitals and implement public health policies. • Greatest achievements were in nursing education. Snow and Epidemiology • John Snow played a key role in setting standards for good public hygiene to prevent the spread of infectious diseases. Infectious Control & Epidemiology: The study of the occurrence, distribution, and spread of disease in humans. Jenner's Vaccine • Edward Jenner tested the hypothesis that a mild disease called cowpox provided protection against protein tidally fatal smallpox. After he intentionally inoculated a boy with pus collected from a milkmaid's cowpox lesion, the boy developed cowpox and survived. When Jenner then infected the boy with smallpox pus, he found the boy had become immune to smallpox. • Because vaccination stimulates long-lasting response by the body's protective immune system, the term immunization is often used synonymously today. Immunology: The study of the body's speciﬁc defenses against pathogens. Ehrlich's "Magic Bullet" • Certain procedures and chemicals can limit, prevent and cure infectious diseases. • Ehrlich undertook an exhaustive survey of chemicals to ﬁnd a "magic bullet" that would destroy pathogens while remaining nontoxic to humans. ¹ Discovered a chemical active agent that causative agent of syphilis, through the arsenic-based drug was toxic to humans. - Discoveries began the branch of chemotherapy. Some people consider Pasteur or Koch to be the Father of Microbiology, rather than Leeuwenhoek. Why might they be correct? Pasteur helped refute spontaneous generation with his wan neck ﬂasks, deﬁned fermentation and pasteurization to save the wine industry, and was instrumental in the development of several vaccines. Koch developed the Koch's postulates for determining the etiology kcal agent for a give disease. He identiﬁed the etiological agent for numerous disease including anthrax and tuberculosis. His lab developed techniques for isolating colonies on agar containing media. Although Leeuwenhoek was the ﬁst to describe and draw microorganisms, Pasteur and Koch both made various conclusions that tremendously improved society and their health. 1.16 Identify 6 health care practitioners who did pioneering research in the areas of public health microbiology ad epidemiology. The 6 key health practitioners that pioneered public health. Public health is a ﬁeld that still exists today that focuses on how disease is spread through populations and techniques to prevent infection of whole ovulation a. Ignaz Semmelweis: Observed that women giving birth that were tended by medical students were dying form puerperal fever at a higher rate than other women. Hypothesized that the medical students were carrying disease particles from the cadaver lab to the obstetric ward and infecting the women. Hypothesis were further conﬁrmed when a doctor that lived his ﬁnger during surgery died from the same disease days later. Instituted a handwashing policy for his medical students (w/ chlorinated lime water) Reduced # of patients who died signiﬁcantly. Joseph Lister: Introduced the concept of antiseptics Started spraying surgical equipment with phenol that was known to reduce odor in sewage. Decreased surgery related infections by 2/3 John Snow: Studied an outbreak in Cholera. Suspected that infection was coming from contaminated water. Carefully mapped out the spread of disease and water sources. Created awareness for the need to clean water and proper sewage systems. Opened up the ﬁeld of epidemiology. Edward Jenner: Created vaccines Vaccines are small pieces of infectious viruses, injected into people to create an immune response to the virus. Started experiments using cowpox, similar virus to the human smallpox. Infected a boy with a sample of cowpox. When boy was exposed to smallpox, he did not get sick. Opened the ﬁeld of immunology Paul Ehrlich: Hypothesized that since bacteria were diﬀerent they could be killed preferentially without harming the host or non-pathogenic bacteria. Looked of the "magic bullet" did not ﬁnd it but discover an arsenic based drug that was toxic to humans, but killed the bacteria Syphillis. Opened the ﬁeld of chemotherapy 1.17 Name two scientists who work with vaccines began the ﬁeld of immunology Edward Jenner was the ﬁrst person to develop a vaccine. Found that immune system creates a long lasting response when exposed to a pathogen. The immune system remembers the pathogen and can ﬁght it oﬀ faster the next time the exposure to the pathogen occurs. Pasteur furthered Jenner's work by producing weakened strains of the same virus to prevent serious disease. Today we use small particles of viruses instead of weakened strains to protect patients, but still achieve immunity. 1.18 Describe the quest for a "magic bullet" After the realization that pathogens cause diseases from Pasteur's germ theory, people sought after a drug that would kill the pathogens, but leave humans unharmed "the magic bullet" Paul Ehrlich spent his career searching for this drug. Hypothesized that diﬀerent bacteria could be killed preferentially, leaving other cells unharmed. He discovered a chemical based on arsenic that would kill pathogens, but was toxic to humans. Did not ﬁnd the "magic bullet" but did open up the ﬁeld of chemotherapy, which is used to ﬁght oﬀ cancer.
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