Microbiology

• Microbiology is the study of microscopic organisms involving handling, identification, and manipulation of organisms not visible to the naked eye
• Louis Pasteur, known as the 'father of microbiology,' coined the term microbiology
• Microbiology deals with the form and structure, reproduction, physiology and metabolism, identification, distribution in nature, and relationships with other living organisms of microorganisms
• Macroorganisms are life forms visible to the naked eye, such as animals, human beings, and plants
• Microorganisms are life forms not visible to the naked eye, with importance in studying health, infections, and treatment modules
• Chains of infections involve microorganisms, reservoir/source, port of exit, modes of transport, port of entry, and susceptible host
• • STERILIZATION: process, either physical or chemical, that destroys all forms of microorganisms, spores, and viruses; killing or removal of all microorganisms, including highly resistant bacterial endospores.
• EQUIPMENTS FOR STERILIZATION: Autoclave, dry heat (Hot-Air Oven), Ethylene Oxide Gas/Filtration. 

  • DISINFECTION: process to eliminate or reduce pathogenic bacteria from inanimate objects; pathogenic bacteria are destroyed during disinfection, but some microorganisms, including bacterial endospores, may remain viable. 
• SOME COMMON DISINFECTANTS: phenol-containing compounds, quaternary ammonium compounds, alcohol (ethanol), chlorine, iodine, etc.
• • Laboratory Tests (its application towards the identification of microorganisms)
  • Culture Techniques 
  • Biochemical Tests 
  •  Serological Tests
• • Immune system in terms of types of immunities and various immune molecules such as
  • Interferons 
  • Cytokines 
  • Complement Protein
• • Importance of microorganisms in: 
  •  Food 
  • Agriculture 
  • Industries 
  •  Environment 
• ANTON VAN LEEUWENHOEK 

  • ‘Father of Bacteriology’ 
  • Dutch lens maker, devised simple apparatus to aid the observation of  microbial forms such shapes of bacteria: spherical, rod, and spiral. 
  • Contributes to the evolution of Microscopy
• Louis Pasteur's contributions:

  • Demonstrated that undesirable life forms could be destroyed by heating at 55°C–60°C for a short period of time, known as pasteurization
  • Discovered that certain bacteria lost their virulence after extensive culturing in the laboratory
  • Suggested the existence of bacteria capable of offering immunity
  • Conducted experiments with attenuated bacilli of anthrax on sheep, goat, and cow, observing that vaccinated animals survived while controls did not
  • Developed a vaccine against rabies, a significant breakthrough in vaccinations
  • Administered an attenuated suspension of rabies virus to Joseph Meister, a 13-year-old boy bitten by a rabid dog, saving him from the disease
• JOHN TYNDALL (1820-1893) 

  • Explained that bacteria existed in two forms: heat-stable and heat-sensitive.
  • Demonstrated that prolonged/ intermittent heating was required to destroy heat-stable forms
• TYNDALLIZATION -  process of intermittent heating which kills both forms of bacteria
• JOSEPH LISTER (1827-1912) 

  • Father of Antiseptic Surgery
  • Established the fundamental principles of antisepsis in surgical practice. 
  • Advocated the use of carbolic acid as an aerosol during surgeries and impregnation of dressings to reduce the risk of post-operative infections
• 
  

  ROBERT KOCH

  BACILLUS OF ANTHRAX 1876

  BACILLUS OF TUBERCULOSIS 1882

  VIBRIO CHOLERAE 1883

  HANSEN

  LEPROSY BACILLUS 1874

  NEISSER

  GONOCOCCUS 1879

  
  

  ALEXANDER ONGSTON 

  STAPHYLOCOCCI 1880

  
  

  EBERTH

  TYPHOID BACILLUS 1880

  
  

  KLEBS AND LOEFFLER

  CORYNEBACTERIUM DIPHTHERIAE 1884

  
  

  ROSENBACH

  STAPHYLOCOCCUS 1886

  
  

  WEICHSELBAUM

  MENINGOCOCCUS  1887

  
  

  DAVID BRUCE 

  MALTA FEVER - BRUCELLA  1887

  
  

  SCHAUDINN AND HOFFMAN 

  SPIROCHAETES - TREPONEMA PALLIDUM 

  1905
• • THUCYDIDES (464-404 BC) Greek historian; he observed that the sick and dying were able to recover because of the care provided by those who were already affected and knew that they would not contract the disease again during a plague epidemic in Athens.
• EDWARD JENNER (1749-1823) - Tested the hypothesis that milkmaids who had been exposed to cowpox (vaccinia) from their herd never got infected with the dreaded small pox (variola) by inoculating them with the fluid from cow pox pustules. The vaccinated individuals reacted mildly and after recovery did not contract small pox when exposed to the virus. 
• Taxonomy is the science of classification, identification, and nomenclature
• Taxonomy sets up arrangements of the kinds of plants and animals in hierarchies of superior and subordinate groups
• Carolus Linnaeus was a Swedish physician and botanist, known as the founder of 'modern taxonomy'
• Binomial nomenclature, originating from Linnaeus, gives each organism two names: a generic name for the genera and a specific name for the species
• In binomial nomenclature, the scientific name of an organism is formed by combining the generic and specific names, with the genus name capitalized and the species name in lowercase, always italicized or underlined separately
• TWO-KINGDOM CLASSIFICATION 

  • Carolus Linnaeus; Mid-17th Century
  • Classified all living organisms into two kingdoms: Kingdom Plantae and Kingdom Animalia
• THREE-KINGDOM SYSTEM 

  • Haeckel (1866); Swiss Naturalist 
  • Placed all unicellular (microscopic) organisms in a new kingdom: Protista 
  • Kingdom Protista, Kingdom Plantae and Kingdom Animalia
• FOUR-KINGDOM SYSTEM

  • Development of the electron microscope (circa 1950). 
  • It was found that Haeckel’s kingdom Protista had some organisms with membrane-bound nucleus and some organisms that lacked intracellular compartments. 
  • Kingdom Protista, Kingdom Plantae, Kingdom Animalia and Kingdom Monera 
• FIVE-KINGDOM SYSTEM 

  • R. H. Whittaker, a botanist; polished the system into five kingdoms in 1967. 
  • Grouped fungi under a separate kingdom

  WHITTAKER’S FIVE-KINGDOM CLASSIFICATION CONSISTS OF THE FOLLOWING KINGDOMS:  

  1. Kingdom Monera (prokaryotic organisms) 
  2. Kingdom Protista (primitive eukaryotic organisms) 
  3. Kingdom Mycota (exclusively fungi)
  4. Kingdom Metaphyta (advanced eukaryotic plants) 
  5. Kingdom Metazoa (all multicellular animals) 
• STRUCTURE AND CLASSIFICATION OF MICROBES 

  PROKARYOTIC CELLS: Blue Green Algae and Bacteria 

  EUKARYOTIC CELLS: Protists, Fungi, Animals and Plants 
• StRUCTURE AND CONTENTS OF A TYPICAL PROKARYOTIC (BACTERIA) CELL 

  1. Prokaryotic cells are smaller compared with eukaryotic cells. 
  2. Cytoplasm is enclosed by the cell membrane. 
  3. Cell organelles freely float, without any membrane.
  4. Nucleus is called NUCLEOID as it lacks the membrane surrounding it
  5. Contains a naked DNA molecule. 
• CELL MEMBRANE/PLASMA MEMBRANE: 

  • Surrounds the bacterial cell. 
  • Acts as a protecting shield for the cell.
  • Encloses all the essential belongings of the cell within it.
• Carboxysomes: protein-bound bacterial organelles.
• Intracellular Nutrient Storage Granules: glycogen, polyphosphate, sulphur, and polyhydroxyalkanoates.
• CYTOPLASM/PROTOPLASM 

  • Gel-like matrix which composed of water, nutrients, wastes, enzymes, and gases. 
  • All the cell’s organelles such ribosomes, mitochondrion, chromosome, and plasmid, are suspended on it.

  Functions for: Cell growth, Metabolism and Replication.
• Ribosomes consist of RNA and protein and are granular-shaped organelles responsible for protein synthesis
• In a bacterial cell, there are 70s ribosomes responsible for reading the instructions on DNA and directing the production of bacterial protein
• Components of 70S Ribosome:

  • It has 30S and 50S subunits
  • Ribosomes are active only when the two subunits, 30S and 50S, are combined together
• Magnesium ion and chemical energy are required for attaching the two subunits to make the ribosome functional
• The activity of 70S ribosome can be blocked by antibiotics such as erythromycin and streptomycin