Welcome to the course of General Microbiology 231

Welcome to the course of General Microbiology (231) By Dr. Samah Noor Semester 1 (Sep 2011)

Lecture 1 History of Microbiology

what is Microbiology? • Microbiology (from Greek, mīkros is“small”, βίος is “life”, is λογία “science ”) • Microbiology: is the discipline of science which deals with the study of organisms that require magnification to be observed (>. 1 mm) • It extends to all phases of biology and is the central point of the modern fields of biotechnology and genetic engineering.

What is Microbiology? • Microbiology is a broad term which includes virology, mycology, parasitology, bacteriology and other branches • Microscope was the major tool, and still very important to study the microorganisms. • It is estimated that only about one percent of the microorganisms present in a given environmental sample are culturable and • The number of bacterial cells and species on Earth is still not possible to be determined

History of microbiology First observations • In 1665, Robert Hooke made the first to record that the life’s smallest structural unit were little boxes, he called “cells”. • Using his two lenses improved microscope he was only capable of showing large cells not microbes • In 1673 -1723, Antonie van Leeuwenhoek observed bacteria and other microorganisms, using a single-lens microscope of his own design • He made detailed drawing of “animalcules” in rain water, feces, and teeth

History of microbiology The theory of Spontaneous Generation Until the mid 1880 s, it was believed that living organisms could be arise spontaneously from nonliving matters Toads, snakes, rats -----> born from moist soil Flies ------> from manure Maggots -----> decaying corpses In 1688 Francesco Redi was an Italian physicial who bow the idea of spontaneous generation by showing that rotting meat carefully kept from flies will not spontaneously produce maggots.

1745 John Needham heated infusion of chicken broth and corn, poured into covered “clean” flasks. Soon contaminated. Said could only be due to spontaneous generation 1765 modified Needham’s experiment: the fluid was sealed in the flasks, and then boiled. noted tat they did not show contamination if sterilized in the sealedflask O 2 1743 -1794 Laurent Lavoisier Discovered oxygen in air. Many thought this could be the “vital principle. ”

The theory of Biogenesis In 1858, German, Rudolf Virchow: biogenesis; all cells came from cells In 1861, French, chemist Louis Pasteur Demonstrated that microbes are in the air everywhere and proof it Deduced that micro organisms can be destroyed by heating. Blocking access to medium will prevent growth

The Golden Age of Microbiology 1857 - 1914 is the golden age of microbiology Rapid discoveries made by Pasteur and Koch Main findings: • Agent of many diseases • Immunity and curing diseases • Chemical prosperities of Microorganisms • Improving microscopy and culturing techniqus • Vaccines • Surgical techniques Note: details found in the Microbiology book

Fermentation and Pasteurization Fermentation is: decomposition of plant and animal tissues (carbohydrates) into alcohols and organic acids. Pasteur noted that the sour wines differed from the normal wines in that they were heavily laden with microscopic rod shaped organisms (bacilli) He concluded that : the yeast ferment sugar to alcohol and that bacteria can oxidize the alcohol to acetic acid Pasteurization is: a heating process to remove microorganisms fruit + Bact+ Yeast____ heat ____ no fermentation_____add yeast___ fermentation These experiments indicated that bacteria were the agents of chemical change in food and they might they also be the cause of disease?

The Germ Theory of Disease • In 1836 Agostino Bassi was the first to show that microbes were the cause of disease • He demonstrated that a silkworm disease was caused by a fungus. • In 1867 Joseph Lister (father of sterile surgery) • applying carbolic acid to dressings that covered wounds to prevent microorganisms from entering the wounds. • Instruments were heat sterilized (boiled) • This approach transformed surgery Carbolic acid spray

Koch’s postulates • In 1881 Robert Koch demonstrated the first direct role of a bacterium in disease • He proposed 4 postulates that could be used to prove whether or not an infectious agent is the cause of a disease.

Immunological studies How animals resisted disease? • In 1880, Pasteur and Roux: prolonged incubation and subculture of bacteria would reduce the virulence of bacteria (chicken cholera). • If injected the bacteria back into the animals they would not get sick, and they developed the ability to resist disease • This process was called “vaccination”, and the protection provided was called “immunity” • Modern vaccines are prepared from living microorganisms, killed pathogens, isolated components of pathogen, and recombinant DNA technique

Modern chemotherapy • Chemotherapy is a chemical treatment of diseases They are two types of chemotherapy: • Synthetic drugs (chemically prepared in labs) • Antibodies (produced normally by fungi and bacteria to prevent others from growing) • In 1928 Alexander Fleming observed that Penicillium fungus inhibited the growth of bacteria, he called the reagent (Penicillin) • Penicillin is used as antibiotics since 1940 s • Researchers are traking the antibiotics-resistance microbes

other important findings in modern microbiology • Koch’s discovery of the tubercule bacillus (Mycobacterium tuberculosis) in 1882. • Advances in cultivation techniques Gelatin -------> solidifying agent -----> microbiological medium Problems: 1) Liquefy at high temperature 2) Degraded by some bacteria • Fannie Hesse, the wife of one of Kochs suggested Agar in place of gelatin 1) Agar melts at 100˚ C , allow incubation at body temperature 2) Agar is not attacked by bacteria • • • Richard Petri, an associate of Koch developed petri dish, allowed isolation of pure cultures. Koch also developed media that was suitable for growing bacteria isolated from the human body, many of which are still in use today

Modern Development of Microbiology • Bacteriology, mycology, and parasitology are studied • Immunology: vaccinations, AIDS, action of interferons • Genomics allowed classification of Bacteria, Fungus, and Protozoa according to their relationship of each others • Virology: molecular biology and electron microscopy advanced our knowledge in virology • Recombination DNA technology: genetically modified microorganisms is modified to manufacture large amount of human hormones and medical substances (1900 s)

Why studying Microbiology? One important goal of microbiology is to better understand the activities of microorganisms to minimize their harmful effects and maximize their beneficial effects.

• Over 90% of microorganisms are either neutral or beneficial to human beings, Less than 10% are harmful Questions we will address in this course (1) What are microorganisms? (2) Why they are important? (3) What activities do they have? (4) How do they reproduce? (5) How do they live? (6) How do they affect us? (7) How can we control them?