Lec. 1 Microbiology PDF

Chapter 1 Introduction to Microbiology Chapter content  Definitions  Sections of Microbiology  History of Microbiology  Scope of Microbiology  Branches of Microbiology  General Characteristics of Microorganisms  Size of Microorganisms  Terminolo...

Chapter 1 Introduction to Microbiology Chapter content  Definitions  Sections of Microbiology  History of Microbiology  Scope of Microbiology  Branches of Microbiology  General Characteristics of Microorganisms  Size of Microorganisms  Terminology used in Basic Microbiology  Questions Bank  External Links 1  Chapter one Microbiology Definition Microbiology is the study of microorganisms – biological entities too small to be seen with the unaided eye. Microbiology is the study of microorganisms, microscopic organisms that include in particular the bacteria, a large group of very small cells that have enormous basic and practical significance. Microbiology is the study of microscopic organisms, such as bacteria, fungi, and protists. It also includes the study of viruses, which are not technically classified as living organisms but do contain genetic material. Sections of Microbiology Microbiology considers all aspects of microbial cells, including their structure, metabolism, diversity, genetics and evolution, ecology and roles in infectious diseases. The science of microbiology developed later than other biological sciences, primarily because needed tools, such as the microscope, had to be 2  developed to convincingly prove that microorganisms (also called microbes) exist. What are functions of microbiology? Microbiologists aim to solve a range of problems affecting our health, the environment, climate and food and agriculture. Depending on the employer, this can include: Studying the prevention, diagnosis and control of infections and specific diseases. Ensuring food and drink is safe to consume. History of Microbiology Scientists first observed microorganisms when the first primitive microscopes were developed during the 17th Century. Anton von Leeuwenhoek was the first to publish observations of bacteria, which he viewed by looking at water with a microscope. In 1684, his drawings of bacteria were published in the Royal Society of London’s journal Philosophical Transactions; these are the first known drawings of bacteria. He was also first to describe protozoa, which are single-celled organisms that include amoebae, and also described yeast, which are fungi, in beer. Microbiology techniques used to disprove the long-held theory of spontaneous generation in the 19th Century. Spontaneous generation was 3 the belief that living things arose spontaneously from a combination of ingredients, often including ingredients that were inorganic. For example, people believed that mice arose from soiled cloth combined with wheat if the combination was left out to sit. Although scientists such as Francesco Redi had disproven spontaneous generation as early as the 17th Century, belief in the theory persisted up to the 19th Century. This started to change when Louis Pasteur conducted experiments using microorganisms. He showed that microorganisms could be filtered out of air by using cotton wool, and he was also able to keep liquids sterile for an extended period of time by boiling them in a swan-necked flask. Other important advancements in the 19th Century included the widespread use of the compound microscope and the development of staining techniques in order to better visualize microorganisms. In addition, people began to realize that microorganisms could cause disease, and did experiments on immunity. The 20th Century was a time of great advancement for all forms of science, including microbiology. The first vaccines and antibiotics were developed, and the first chemotherapeutic agents were used to treat bacterial diseases such as syphilis. Deoxyribonucleic acid (DNA) was discovered to be the genetic material of the cell, which opened up the field of genetics research and allowed more recently for sequencing the genomes of microorganisms. 4 What is scope of microbiology? The scope of Microbiology is huge because of the involvement of microbiology in various fields such as Pharmacy, Medicine, clinical research, agriculture, dairy industry, water industry, nanotechnology & chemical technology. Who are Microbiologists? A person who specializes in this field is called as “Microbiologists”. Which is the best field in microbiology? The possible job profiles that you can enjoy working in are: Biomedical Scientist. Clinical Research Associate. Microbiologist. Pharmacologist. Food Technologist. Scientific Laboratory Technician. Physician Associate. Research Scientist. Keep a tab of what is going on in the different industries of the country. If you are a graduate or a post-graduate who is willing to start his/her career, it is advised to take specialized training in any of the following: 5 Agricultural Microbiology Industrial Microbiology Evolutionary Microbiology Nano Microbiology Cellular Microbiology Soil Microbiology Veterinary Microbiology Generation Microbiology Virology Water Microbiology Pharmaceutical Microbiology Microbial Genetics Environmental Microbiology 6 Branches of Microbiology By Taxonomy  Bacteriology: the study of bacteria.  Immunology: the study of the immune system. It looks at the relationships between pathogens such as bacteria and viruses and their hosts.  Mycology: the study of fungi, such as yeasts and molds.  Nematology: the study of nematodes (roundworms). 7  Parasitology: the study of parasites. Not all parasites are microorganisms, but many are. Protozoa and bacteria can be parasitic; the study of bacterial parasites is usually categorized as part of bacteriology.  Phycology: the study of algae.  Protozoology: the study of protozoa, single-celled organisms like amoebae.  Virology: the study of viruses. 8 9 General Characteristics of Microorganisms Prokaryotes: No nucleus and organelles Eukaryotes: Membrane bound nucleus and organelles Acellular agents (Viruses): Genomes contain either DNA or RNA; newer agent is proteinaceous 10 Size of microorganisms Microorganisms vary in size ranging from 10 nm (nanometers) to 100 µm (micrometers): Viruses in nm = 10-9 m (meter) Bacteria in µm = 10-6 m Helminths in mm = 10-3 m 11 Harmful Microorganisms Disease and decay are neither inherent properties of organic objects, nor are caused by physical damage, it is microorganisms that bring about these changes. We are surrounded by bacteria, viruses, and fungi. Many microorganisms cause diseases in cattle, crops and others are known for entering human bodies and causing various diseases. Examples of familiar human diseases are: Bacteria: pneumonia, bacterial dysentery, diphtheria, bubonic plague, meningitis, typhoid, cholera, salmonella, meningococcal Virus: Chickenpox, measles, mumps, German measles, colds, warts, cold sores, influenza Protozoa: amoebic dysentery, malaria, Fungi: ringworm, athlete’s foot 12 Useful Microorganisms As decomposers, bacteria and fungi play an important role in an ecosystem. They break down dead or waste organic matter and release inorganic molecules. Green plants take these nutrients which are in turn consumed by animals, and the products of these plants and animals are again broken down by decomposers. Yeast is a single-celled fungus that lives naturally on the surface of the fruit. It is economically important in bread-making and brewing beer and also in the making of yoghurt. Most microorganisms are unicellular; if they are multicellular, they lack highly differentiated tissues. There are fundamentally two different types of cells, One being Prokaryotic and the other Eukaryotic 13 Classification of microorganisms System for organizing, classifying, and naming living microorganisms Primary concerns of taxonomy are classification, nomenclature, and identification. Nomenclature: Learn Binomial (scientific) nomenclature Genus –Saccharomyces, always capitalized species - cerevisiae, lowercase Both italicized or underlined: Saccharomyces cerevisiae or Saccharomyces cerevisiae Identification: The process of microbial identification and placing them in a taxonomic scheme includes: 1. Microscopic morphology and colony appearance 2. Physiological/biochemical characteristics 3. Chemical analysis 4. Serological analysis 14 5. Genetic and molecular analysis a. G + C base composition b. DNA analysis using genetic probes c. Nucleic acid sequencing and rRNA analysis Major groups of Microorganisms: 1. Bacteria: Bacteriology 2. Fungi: Mycology 3. Algae: Phycology 4. Virus: Virology 5. Protozoa: Protozoology 15 Terminology used in Basic Microbiology 1. Aerobe = organisms that grow in the presence of atmospheric oxygen 2. Anaerobe = grows in absence of free oxygen 3. aerotolerant anaerobes = microbes that grow equally well whether or not oxygen is present 4. facultative anaerobes = microbes that don’t require oxygen for growth but do grow better in its presence 5. microaerophile= requires a low level of oxygen for growth around 2 to 10% but is damaged by normal atmospheric oxygen level 6. monotrichous = having a single flagellum 7. amphitrichous = having single flagellum at each end 8. lophotrichous = cluster of flagella at one or both ends 9. peritrichous = flagella all over the surface 10.attenuation = reduced virulence but can provoke the immune system 11.pathogen = any virus, bacteria or other agents that cause disease 12.pathogenicity = ability to cause disease 13.virulence = degree or intensity of pathogenicity of an organism 14.disinfection = killing, inhibition or removal of microorganisms that may cause disease. it usually refers to the treatment of inanimate objects 16 15.sterilization = process by which all living cells, viable spores, viruses, and viroids are either destroyed or removed from an object or habitat 16.sanitization = reduction of the microbial population on an inanimate object to levels judged safe by public health standards 17.bacteremia= presence of viable bacteria in the blood 18.septicemia = severe condition of bacteremia which includes rapid multiplication of bacteria and toxins in the blood 19.viremia = presence of the virus in the blood 20.pyrogenic = inducing fever 21.antipyretic = which reduces temperature, given in case of fever 22.hemolysis = disruption of red blood cells and release of their haemoglobin 23.α-hemolysis = partial hemolysis, the greenish zone of incomplete hemolysis forms around the colony 24.β-hemolysis = clear zone of complete hemolysis 25.γ-hemolysis = no hemolysis 26.antibiotic = substance of microbial origin or its derivative that kills susceptible microorganism or inhibits their growth 27.antibody = also known as immunoglobin, a glycoprotein produced in response to the antigen 17 28.antigen = substance, when introduced into the body, stimulates the production of antibodies 29.bacteriostatic = inhibiting the growth of bacteria without killing them 30.bactericide = an agent that kills bacteria 18 Questions Bank Frequently Asked Questions Q1: Define medical microbiology. Medical microbiology can be defined as a branch of microbiology that deals with the diagnosis, prevention and treatment of infectious diseases. Q2: What is the golden era of microbiology? The time between 1850 to 1915 is considered as the golden era of microbiology. Q3: What is the relevance of microbiology in nursing? In nursing, microbiology helps the professionals to understand the interaction between humans and microbes. It also helps in 19 understanding the basic morphology, reproductive and biochemical properties of microorganisms. Q4: State the contribution of scientists in microbiology. Louis Pasteur and Robert Koch gave the germ theory of disease and Koch’s postulates, which was a big contribution to the beginning of microbiology. 20