PHC6562 Lecture1 Part1 Slide 1: Slide 1 Welcome to the first lecture for the Microbiology For Healthcare Workers course. The lectures for this course will be numbered in sequence as presented throughout the semester. The first lecture is labeled Lecture 1. Lecture 1 will be divided into Parts 1 and 2 for convenience; this is an effort on my part to avoid long presentations. Most, but not all of the lectures in this course will be divided into 2 parts. The formal course number is PHC6562. As described in the introductory lecture, this course is divided into 2 modules. The first module comprises of lecture material that covers the basic concepts of microbiology and infectious diseases. Lectures 1 through 6 make up Module 1. The second module covers applications of Microbiology in Public Health. Module 2 is comprised of Lectures 7 through 12. As an instructor for this course, I encourage questions being asked on material that may not have been clearly presented in the lectures. Since this is a web-based course, I encourage that questions be posted on the discussion board. This will enable other students to view the questions, as well as view Instructor and TA responses to the questions. However, if there is a need to contact instructors or the TA regarding course material or other matter, please do not hesitate do send out emails to us as needed. Slide 2: Lecture 1 Overview of Microbiology In Lecture 1, I will introduce you to the discipline of Microbiology. In Part 1, I will start with a basic introduction to Microbiology, and then provide a historical perspective on how this discipline evolved. In Part 2, I will introduce you to groups of microorganisms, which are the main players in the field of Microbiology. Next, I will discuss the history of the microscope, from the historical perspective, to the description of the current modern types of microscopes that are routinely being used in diagnostic and research microbiology laboratories. I will end part 2 lecture 1 with a preview of some of the concepts that are covered in Chapters 1 and 3 of the assigned text book, Microbiology: A system's Approach. Slide 3: Microbiology The question posed on this slide is, how does one define Microbiology? “Biology” can be defined as the study of life, and “micro” represents the study of microorganisms. These are organisms that cannot be viewed by the unaided eye, and can only be seen through the microscope. There are endless scopes, disciplines and applications of microbiology, which are described in detail in Chapter 1 of the assigned text book. The various disciplines of Microbiology correspond mostly to the types of microorganism under study. For instance, virology is the study of viruses, bacteriology is the study of bacterial pathogens, mycology is the study of fungal organisms, and parasitology is the study of parasites and the diseases they cause. The applications of microbiology are boundless. For instance, in the diagnosis of infectious diseases, the tools of microbiology are being utilized in the laboratory to detect the presence of the pathogen that cause the disease. This laboratory diagnosis confirms the diagnosis for the physician or other healthcare workers requesting specific diagnostic tests to detect the presence of the suspected organism, or pathogen. Microorganisms such as the bacterium Escherichia coli, or E. coli, are also used widely in the research field and industry for the production of useful or important biological products such as vaccines and recombinant proteins. Our world is filled with microorganisms- they are everywhere in our environment and living with us in and on our bodies. Pathogens are microorganisms that can cause infectious diseases. Only 3% of microorganisms can actually cause these specific infectious diseases by virtue of them being ‘infectious”. However, there is another category of microorganism termed “opportunistic pathogens”. These microorganisms normally do not make a person sick and can live harmoniously on our bodies as “commensals”. However, if the situation changes for the host, such as for hosts that become immunocompromised, or if these opportunistic pathogens find their way on persons of extreme ages, for instance (the very young or the very old), these same commensal microbes can become pathogenic and cause infectious diseases. There are also many microorganisms such as some specialized yeasts that we will discuss later in this lecture, that can be beneficial in food and beverage industries. Slide 4: Slide 4 This slide shows the relative sizes of various objects, and the detection devices used to visualize them. The power of the eye, the most basic image sensor, has its limits. Anything smaller than the width of a single human hair cannot be seen with the naked eye. When the light microscope was developed in the later 1600’s, a whole new world of tiny wonders was discovered. The basic light microscope allows us to visualize objects such as the different types of cells such as bacteria, as well many other types of cells. The invention of the microscope opened up a whole new world. From the knowledge that microorganisms exist all around us, the field of microbiology was born. The electron microscope was invented in the mid-twentieth century. This instrument made it possible to detect even smaller objects that cannot be seen using a light microscope. This includes smaller molecules and viruses. The detection power of most electron microscopes stops just short of being able to visualize incredibly small structures such as the electron orbital systems of individual atoms. Atoms are considered the smallest units of an element that have the characteristics of that element. Similarly, cells are the smallest units of an organism capable of functioning independently. In Lecture 1 this course, we will learn about the different types of biological cells and the different classification of microorganisms that exist all around us. Slide 5: Slide 5 In this slide, I am illustrating again the point I made earlier about the different types of microorganisms that are found all around us. Only 3% of all microorganisms are pathogenic, and 10% are opportunistic pathogens. Slide 6: Beneficial Microorganisms There are many microorganisms that are utilized in various industries to prepare processed food and drinks such as bread, yogurt, wine, and beer. This slide lists the different ways these microorganisms become beneficial to us the consumers. Since ancient times, societies all over the world learned different ways to harness microbes for beneficial aspects, even before they knew microorganisms even exist! Microbes in the environment participate in the cycle of life in the ecosystem, mostly as decomposers, and thus function as “recyclers”. An example is bacterial actions on decomposing materials in swampy areas, and as a result, we can detect the odor of “marsh gas” or methane in these areas. Microbes involved as scavengers are usually non-pathogenic and free-living. Microbes in the environment are also involved in the process of recycling of carbon, nitrogen, sulfur, iron and phosphorus, resulting in the return of these elements to nature for reuse. There are many types of foods and beverages that are dependent on microorganisms for their production. The list is long and includes cheese, bread, many types of dairy products, wine, beer and many other types of drinks. Microbes have been utilized in the production of fermented foods for thousands of years. Fermentation is the process involving a series of chemical reactions, mediated by bacterial enzymes. During fermentation, sugars in the original food are broken down into acids or alcohol, and carbon dioxide. Which organism used during this process determines the taste and aroma of the product. For example, yeasts are fungi that are efficient fermenters of sugar into alcohol and carbon dioxide. This property of yeast is exploited in the production of breads and alcoholic beverages. The yeast strain Saccharomyces cerevisiae, known as “bakers yeast”, is commonly used for this purpose. Carbon dioxide produced by this yeast strain allows dough to rise, and is used to bake bread. Yogurt and other dairy products such as cheese is another example of popular food that requires microbes for production. Yogurt is fermented milk that is preserved by its acidity, and contains live bacterial cultures of predominantly Lactobacilli species, (which is mainly Lactobacillus acidophilus species). Decreased pH in yogurt causes milk to thicken and inhibit growth of pathogens. Foods supplemented with live microbes are called “probiotics”. Advocates of probiotics claim that there are many health benefits to consumption, which include partial replacement of normal flora for individuals on antibiotic therapy, reduction of blood pressure, regression of tumors as well as decreased diarrhea and gas production. Beer is brewed from barley, hops and water, and uses yeast to produce the alcohol during fermentation. Wine is fermented grape juice, that uses yeast (Saccharomyces ellipsoidues) to produce alcohol and carbon dioxide. Yeast extract, which is prepared from autolysing yeasts (separated using specialized centrifuges such as shown in the middle figure at the bottom of this slide) can be purchased for home use, such as for baking. Please do not worry about memorizing the specific names of beneficial bacteria and yeasts I just mentioned here. These names will not be asked on the exam pertaining to Lecture 1. Slide 7: Slide 7 Microbes are also used as research tools. Genetics and molecular biology fields have benefited greatly from experimentations using different types of microorganisms such as bacteria and viruses. Biologists have capitalized on the fact that microorganisms are easy and inexpensive to grow, and reproduce rapidly. A very important bacterial species commonly utilized in the cloning of many important gene products for use in medicine and research is the gram-negative bacterium Escherichia coli.