1. INTRODUCTION TO MICROBIAL WORLD Refer Ch. 1 of Text Book ‘Microbiology with Diseases and Taxanomy’ 2nd ed. By Robert

1. 1. INTRODUCTION TO MICROBIAL WORLDRefer Ch. 1 of Text Book ‘Microbiology with Diseases and Taxanomy’ 2nd ed. By Robert Bauman. Pearson. 2007. Famous quote of Louis Pasteur (1822-1895): Three things, WILL, WORK, & SUCCESS, fill human existence. ‘To will is a great thing, for Action and Work usually follow Will, and almost always Work is accompanied by Success. Will opens the the door to success both brilliant and happy; Work passes these doors, and at the end of the journey Success comes to crown one’s efforts.’

2. Factors and Questions leading to the ‘birth’ of microbiology: • What is the function of nodules at the base of plants? • Why does bread turn sour? • What causes new diseases?

3. 2.Early History • Greek physician Hippocrates (460 -377 B.C.) –link between environment and disease • Greek historian Thucydides (460-404 B.C.) – survivors of plaque who had contact with victims? • Antoni van Leeuvwenhoek (1632-1723, a Dutch tailor, merchant and lens grinder) – first discovered the bacterial world in 1674.

4. 3.Microbiolgy deals with: Microbiology often has been defined as the study of microorganisms (organisms and agents too small to be seen by an unaided eye. It deals with: • Spontaneous generations • Reasons fermentations occurs • Cause of diseases

5. 3.1 The discovery ofmicroorganisms • The suspected existence and responsibility for disease by microbes was mentioned by Roman philosopher Lucretius (98-55B.C.) and the physician Girolamo Fracastoro (1478-1553). • Earliest microscopic oberservations, using Galileo’s microscope, were made on bees and weevils by Italian Francesco Stelluti between 1625 and 1630. • First drawing of a microorganism was published in Robert Hooke’s Micrographia in 1665. • Accurate oberservations of microorganisms was made by the amateur microscopist Antony van Leewenhoek of Delft (1632-1723).

6. 3.2 The most accurate hyphothesis during 10th century • IbnSina (known as Avicenna in Latin and in the West) in his masterpiece The Canon of Medicine (United States National Library of Medicine, MS A 53) states that "Body secretions of a host organism (e.g., human being) are contaminated by tainted foreign organisms that are not visible by naked eye before the infection."

7. 4.How can microbes be classified? • Carolus Linnaeus, a Swedish botanist, (1707-1778)- developed a taxonomic system for naming plants and animals and grouping organisms (fungi,protozoa,algae, bacteria, archaea, and small animals) together. Biologists still use a modification of Linnaeus’ taxonomy today. • Technically, viruses are not organisms because they neither replicate themselves nor carry on the chemical reactions of living things.

8. 4.1 Characters of different microorganisms All living organisms can be classified as either eukaryotic or prokaryotic. Eukaryotes are organisms whose cells contain a nucleus composed of genetic material surroundedby a distinct membrane. Prokaryotes are unicellular microbes that lack a truenucleus. Within these categories, microorganisms are further classified as follows: Fungi are relatively large microscopic prokaryotes and include molds and yeasts. These organisms obtain their food from other organisms and have cell walls. Molds are typically multicellular organisms that grow as long filaments, called hyphae, that intertwine to make up the the body of the the mold, such as the cottony growths on cheese, bread, and jams. Pennicillium chrysogenum produces antibiotic pennicillin. They reproduce by sexual or asexual spores that produce a new individual without fusing with another cell

9. Yeasts • Yeasts are unicellur and typically oval to round. • They reproduce asexually by budding, a process in which a daughter cell grows off the mother cell. Some also produce sexual spores (Ascomycetes). • Saccharomyces cerevisae is used in the bakery and alcohol industries. Candida albicans causes yeast infection in women.

10. Protozoa • Protozoa are single-celled eukaryotes that are similar to animals in their nutritional needs and cellular structure. • Most are capable of locomotion (by pseudopodia or false foot, cilia, or flagella) and some cause disease. • Types of protozoa movements: Pseudopodia are extensions of cell that flow in the direction of travel; Cilia are short hairlike protusions of a cell the beat rhythmically to propel the protozoan through its environment; Flagella are also extensions of a cell, but are fewer, longer, and more whiplike than cilia. Malaria causing Plasmodium are nonmotile in mature forms • They typically live in water, but some inside animal hosts, where they cause disease. • Most reproduce asexually, though some are sexual.

11. Algae • Algae (Plural of Latin alga, meaning seaweed)are plant-like eukaryotes that are photosynthetic; that is, they make their own food from carbon dioxide and water using energy from sunlight. They are unicellular or multicelluar. • They are categorised on basis of their pigmentation, their storage products, and the composition of their cell walls. • Large algae, commonly called seaweeds and kelps, are common in the world’s oceans. Chemicals from their gelatinous cell walls are used as thickeners and emulsifiers in food and cosmetic products, as well as laboratory media. • Unicellular algae are common in freshwater ponds, streams, lakes and oceans. They are food of small aquatic and marine animals and provide most of the world’s oxygen as a by-product of photosynthesis. The glasslike cell walls of diatoms are used in polishing compounds.

12. Prokaryotes- Bacteria and Archaea • Bacteria are unicellular prokaryotes whose cell walls are composed of peptidoglycan(though some bacteria lack cell walls). Most bacteria are beneficial acting as micrbial recyclers for organic waste but some cause disease. • Archaea are single-celled prokaryotes whose cell walls lack peptidoglycan and instead are composed of other polymers. They survive in high saline lakes, acid hotsprings, and oxygen depleted mud at the bottom of swamps.

13. Viruses • Viruses are the smallest of all microbes and were hidden from microbiologists until the invention of the electron microscope in 1932. • All are acellular obligatory parasites causing many animal and plant diseases and human epidemics such as small pox, rabies, influenza,AIDS, the common cold, and some cancers. • Technically, viruses are not organisms because they neither replicate themselves nor carry on the chemical reactions of living things.

14. 5. The theory of spontaneous generation (abiogenesis) • This theory proposes that living organisms can arise from nonliving matter. It was proposed by Aristotle (384–322 BC) and was widely accepted for almost 2000 years, until flies-infested meat experiments by Francesco Redi (1626–1697) challenged it. • In the 18th century, British scientist John T. Needham (1713–1781) conducted boiling beef gravy and plant infusion experiments in air-tight vials suggesting that ‘life force’ causes inanimate matter to come to life and perhaps spontaneous generation of microscopic life was indeed possible, but in 1799, experiments by Italian scientist Lazzaro Spallanzani (1729–1799) reported results that contradicted Needham’s findings. • The debate continued until experiments by French scientist Louis Pasteur (1822–1895) using swan-necked flasks that remained free of microbes disproved the theory definitively. • The English physicist John Tyndall (1820-1893) dealt a final blow to spontaneous generation in 1877 by demonstrating that dust did indeed carry germs and that if dust was absent browth remained sterile even if directly exposed to air.

15. 5.1 Contribution of theory of abiogenesis to microbiology The debate over spontaneous generation led in part to the development of a generalized scientific method by which questions are answered through observations of the outcomes of carefully controlled experiments. It consists of four steps: 1. A group of observations leads a scientist to ask a question about some phenomenon. 2. The scientist generates a hypothesis—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, rejects, or modifies the hypothesis It also contributed to the ‘Golden Age Of Microbiology”

16. 6.The Golden Age of Microbiology(between late 19th century and early 20th century) • Pasteur’s work with swan neck flasks ushered in the Golden Age of Microbiology. Within 60 years (1857-1914), • a number of disease-causing microbes were discovered, • great strides in understading microbial metabolisn were made, • and techniques for isolating and characterizing microbes were improved.

17. 6.1 What cause disease? • Pasteur’s discovery that bacteria are responsible for spoiling wine led to his hypothesis in 1857 that microorganisms are also responsible for diseases • This idea came to be known as the ‘germ theory of disease’ • Early investigators suspected that cholera, tuberculosis, and anthrax are each caused by a specific germ, called a pathogen • Today we know that some diseases are genetic and allergic reactiona and enviromental toxins cause others • Germ theory applies only to infectious diseases.

18. 6.2 Scientists associated with cause of disease • Galen (Greek physician, 129-199) accepted the imbalance of 4 humors (blood, phelgm, yellow bile [choler], and black bile [melancholy] were associated with disease • In the 15th century, Fracastoro and others suggested that supernatural forces, poisonous vapors called miasmas, and imbalances among the four humors thought to be present in the body, produced disease • Support for the germ theory of disease began in the 19th century, when Agostino Bassi (1773-1856) first showed in 1835, that a microorganism could cause a fungal disease in silkworm. He also suggested that many diseases were due to microbial infections

19. 6.2 Scientists and cause of disease • In 1845, M.J. Berkeley proved that the great Potato Blight of Ireland was caused by a water mold • In 1853, Heinrich de Bary, showed that smut and rust fungi caused cereal crop diseases • Pasteur (1822-1895), who studied fermentation, later showed that the pebrine disease of silkworm in France was due to a protozoan parasite • English surgeon Joseph Lister (1827-1912), developed a system of antiseptic surgery using phenol to prevent microorganisms from entering wounds • The discovery and work on virus in the 19th century was initiated by Charles Chamberland’s (1851-1908)porcelain bacterial filter and later by Dimitri Ivanowski and Maritus Beijerinck who worked on tobacco mosaic disease.

20. 6.3 Koch’Postulates • The first demonstration of the role of bacteria causing disease was from the study of anthrax by the German physician Robert Koch (1843-1910) who used the criteria proposed by his former teacher Jacob Henle (1809-1885), to establish the relationship between Bacillus anthracis and anthrax. He was responsible for advances in staining, culture media & sterilization and his anthrax work included the following steps: • Koch injected healthy mice with material from diseased animals, and the mice became ill • After transferring anthrax by inoculation through a series of 20 mice, he incubated a piece of anthrax-infected spleen containing anthrax bacillus in beef serum • The bacillus grew, reproduced, and produced endospores • When the isolated bacilli or their spores were injected into mice, anthrax developed His criteria for proving the causal relationship between microorganism and a specific disease are known as Koch Postulates. His study was later confirmed independenly by Pasteur and his coworkers. His 1884 work on Mycobacterium tuberculosis as the causal agent of tuberculosis

21. 6.3.1 ETIOLOGY • Etiology deals with the study of causation of disease. It is associated with Koch’s Postulates: 1. The suspected causal agent must be found in every case o the disease and absent from healthy hosts 2. The agent must be isolated and grown outside the host 3. When the agent is introduced to a healthy, susceptible host, the host must get infected with the disease 4. The same agent must be reisolated from the diseased experimental host.

22. 6.4 How to prevent infection and disease? • In the 19th century, modern principles of hygiene,such as those involving sewage and water treatment, personal cleanliness, and pest control, were not widely practiced. • In approximately 1848, Viennese physician Ignaz Semmelweis (1818–1865) hypothesized that “cadaver particles” from the hands of the medical students caused puerperal fever during child birth, and required medical students to wash their hands in chlorinated lime water before attending births • A few years later, English physician Joseph Lister (1827–1912) advanced the idea of antisepsis in health care settings, reducing deaths among his patients by two-thirds with the use of phenol. • Florence Nightingale (1820–1910), the founder of modern nursing, introduced antiseptic techniques that saved the lives of innumerable soldiers during the Crimean War of 1854–1856.

23. 6.4 Prevention of disease In 1854, observations by the English physician John Snow (1813–1858) mapping the occurrence of cholera cases in London led to the foundation of two branches of microbiology: infection controland epidemiology, the study of the occurrence, distribution, and spread of disease in humans. The field of immunology, the study of the body’s specific defenses against pathogens, began with the experiments of English physician Edward Jenner (1749–1823), who showed that vaccination with pus collected from cowpox lesions prevented smallpox The field of chemotherapy, a branch of medical microbiology in which chemicals are studied for their potential to destroy pathogenic microorganisms, began when German microbiologist Paul Ehrlich (1854–1915) began to search for a “magic bullet” that could kill microorganisms but remain nontoxic to humans. By 1908, he had discovered chemicals effective against the agents that cause sleeping sickness and syphilus

24. 6.3.2 Summary of Golden Age of Microbiology (1857- 1907) • Pasteur – development of Industrial microbiology, Pasteurization (food and beverage technonogy) • Buchner – Microbial metabolism, Genetics, Genetic engineering • Koch – Koch’s posthulates – Etiology • Ivanowski – Virology • Beijerinck, Winogradsky – Environmental microbiology, Ecological microbiology • Gram – Microbial morphology • Lister, Nightingale – Antiseptic medical techniques, Hospital microbiology • Jenner, von Behring, Kitasato – Serology, Immunology • Ehrich – Chemotheraphy • Fleming – Pharmaceutical microbiology

25. 6.3.3 What causes fermentation • The mid-19th century also saw the birth of the field of industrial microbiology (or biotechnology), in which microbes are intentionally manipulated to manufacture products. • Pasteur’s investigations into the cause of fermentation led to the discovery that yeast can grow with or without oxygen, and that Bacteria ferment grape juice to produce acids, whereas yeast cells ferment grape juice to produce alcohol. • These discoveries suggested a method to prevent the spoilage of Wine by heating the grape juice just enough to kill contaminating bacteria, so that it could then be inoculated with yeast. • Pasteurization, the use of heat to kill pathogens and reduce the number of spoilage microorganisms in food and beverages, is an Industrial application widely used today.

26. 6.3.3 Fermentation In 1897, experiments by the German scientist Eduard Buchner (1860–1917) demonstrated the presence of enzymes, cell-produced proteins that promote chemical reactions such as fermentation. His work began the field of biochemistry and the study of metabolism, a term that refers to the sum of all chemical reactions in an organism.

27. 7. The Future of Microbiology • Science writer Bernard Dixon talks about the bright future of microbiology due to: 1. It has a clear vision 2. It has great practical significance • Microbiologists are called upon to create new drugs and vaccines using recombinant DNA technology • Industrial microbiology – food, energy, new antimicrobial agents, new industrial processes, and bioremedation • Environmental microbiology- overcoming pollution, toxic wastes, and protecting food and crops from microbial damage • Medical microbiology – microbial biofilms for human tissues • BIGGEST CHALLENGE facing microbiologists will be to assess the implications of new discoveries and technological developments.

28. 7.1 What will the future hold? Among the questions microbiologists are working to answer today are the following: • What prevents certain life forms from being grown in the laboratory? • Can microorganisms be used in ultraminiature technologies such as computer circuit boards? • How can an understanding of microbial communities help us understand communities of larger organisms? • What can we do at a genetic level to defend against pathogenic microorganisms? • How can we reduce the threat of new and re-emerging infectious diseases?

29. 8. Review assignment questions • What do you think are the the 5 most important research areas to pursue in microbiology. Give reasons for your choice • Describe Pasteur’s work on microbial fermentations • Discuss the contributions of Lister, Pasteur, and Koch to ‘germ theory of disease’ and to the prevention of diseases • Describe Koch’s postulates. What is a pure culture? Why are pure cultures important to Koch’s postulates • What are Koch’s postulates? Why are they important? • Describe Scientific method in your own words. Why is it important to have a control group?

30. 8. Review questions 7. How did Pasteur and Tyndall finally settle the ‘spontaneous generation’ controversy? 8. Describe and contrast prokaryotic and eukaryotic cells 9. Summarise the ‘Golden Age of microbiology’ 10. What is a virus? 11. How would you classify microorganisms? 12. Defend this statement: “The investigations of Antoni van Leeuwenhoek changed the world forever” 13. Discuss briefly about the procedure and significance of Gram’s stain.

31. 8.1 How to answer and marks allocation for the questions • The students are to form a group of four students per group • Each group will randomly select and answer one assignment question • The answer to the question should be about 500 words making sure that is no plagiarism of text from internet or textbook. Students will be penalised for such activity, as they will lose marks. • To avoid plagiarism, the students are encouraged to translate the information from internet or textbook in their own words while citing the source of reference • The answer could be divided into: Introduction (10marks); Contents (50 marks); Conclusion (10 marks); References at least 5 (10 marks); Oral presentation of about 10-15 min consisting of about 10 ppt slides (10 marks)