oral microbiology

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 Microorganisms are organisms that are too small to be
seen with the unaided eye.
 “Germ” refers to a rapidly growing cell.
Microbes in Our Lives

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WHY STUDY
MICROBIOLOGY
 Public Health Applications
 Food Applications
 Industrial Applications
 Biofuels Applications
 Biopharmaceutical applications

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Microorganisms
 Decompose organic waste
 Are producers in the ecosystem by photosynthesis
 Produce industrial chemicals such as ethanol
and acetone
 Produce fermented foods such as vinegar, cheese,
and bread

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Scientific Names
 Are italicized or underlined. The genus is capitalized
and the specific epithet is lower case.
 Are “Latinized” and used worldwide.
 May be descriptive or honor a scientist.

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Scientific Names
 Staphylococcus aureus
 Describes the clustered arrangement of the cells
(staphylo-) and the golden color of the colonies
(aur-).

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Scientific Names
 Escherichia coli
 Honors the discoverer, Theodor Escherich, and
describes the bacterium’s habitat–the large intestine
or colon.

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Bacteria
 Prokaryotes
 Peptidoglycan cell walls
 Binary fission
 For energy, use organic
chemicals, inorganic
chemicals, or photosynthesis
Figure 1.1a

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Viruses
 Acellular
 Consist of DNA or RNA core
 Core is surrounded by a
protein coat.
 Coat may be enclosed in a
lipid envelope.
 Viruses are replicated only
when they are in a living
host cell.
Figure 1.1e

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Fungi
 Eukaryotes
 Chitin cell walls
 Use organic chemicals for
energy.
 Molds and mushrooms are
multicellular consisting of
masses of mycelia, which
are composed of filaments
called hyphae.
 Yeasts are unicellular.
Figure 1.1b

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Modern Developments in Microbiology
 Bacteriology is the study of bacteria.
 Mycology is the study of fungi.
 Parasitology is the study of protozoa and parasitic
worms.
 Recent advances in genomics, the study of an
organism’s genes, have provided new tools for
classifying microorganisms.

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Modern Developments in Microbiology
 Immunology is the study of
immunity.
Figure 1.4 (3 of 3)

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Modern Developments in Microbiology
 Virology is the study of viruses.
 Recombinant DNA is DNA made from two different
sources. In the 1960s, Paul Berg inserted animal DNA
into bacterial DNA and the bacteria produced an animal
protein.
 Recombinant DNA technology, or genetic engineering,
involves microbial genetics and molecular biology.

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Bioremediation
 Bacteria degrade organic
matter in sewage.
 Bacteria degrade or detoxify
pollutants such as oil and
mercury.
UN 2.1

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Biological Insecticides
 Microbes that are pathogenic to insects are alternatives
to chemical pesticides in preventing insect damage to
agricultural crops and disease transmission.
 Bacillus thuringiensis infections are fatal in many
insects but harmless to other animals, including
humans, and to plants.

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Modern Biotechnology and Genetic
Engineering
 Biotechnology, the use of microbes to produce foods
and chemicals, is centuries old.
 Genetic engineering is a new technique for
biotechnology. Through genetic engineering, bacteria
and fungi can produce a variety of proteins including
vaccines and enzymes.

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Modern Biotechnology and Genetic
Engineering (continued)
 Missing or defective genes in human cells can be
replaced in gene therapy.
 Genetically modified bacteria are used to protect crops
from insects and from freezing.

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Microbes and Human Disease
 Bacteria were once classified as plants giving rise to
use of the term flora for microbes.
 This term has been replaced by microbiota.
 Microbes normally present in and on the human body
are called normal microbiota.

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 Normal microbiota
prevent growth of
pathogens.
 Normal microbiota
produce growth factors
such as folic acid and
vitamin K.
Normal Microbiota

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Infectious Diseases
 When a pathogen overcomes the host’s resistance,
disease results.
 Emerging infectious diseases (EID): New diseases and
diseases increasing in incidence.

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Exam Questions
 Definitions
 Differentiate cell walls of
Gram +ve & Gram –ve
bacteria
 Prokaryote Vs Eukaryote
 Nutrition, environment,
staining

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Bacterial Membrane Structures
Structure Chemical Constituents
Plasma Membrane Phospholipids, proteins, enzymes for energy, membrane potential, transport.
Cell Wall
Gram +ve Bacteria
Peptidoglycan Glycan chains of GlcNAc and MurNAc cross linked by peptide bridge.
Teichoic Acid Polyribitol phosphate or glycerol phosphate cross linked to peptidoglycan.
Lipoteichoic Acid Lipid linked teichoic acid.
Gram -ve Bacteria
Peptidoglycan Thinner version of that found in Gram positive bacteria.
Periplasmic Space Enzymes involved in transport, degradation, and synthesis.
Outer Membrane Phospholipids with saturated fatty acids.
Proteins Porins, lipoprotein, transport proteins.
LPS Lipid A, core polysaccharide, O antigen.
Other Structures
Capsule Polysaccharides (disaccharides and trisaccharides) and polypeptides.
Pili Pilin, adhesins.
Flagellum Motor proteins, flagellin.
Proteins M proteins of streptococci (for example).
Bacterial Membrane Structures

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Function Component(s)
Structural Rigidity All.
Packaging Of Internal Contents All.
Permeability Barrier Outer membrane or plasma membrane.
Metabolic Uptake
Membranes and periplasmic transport
proteins, porins, permeases.
Energy Production Plasma membrane.
Adhesion To Host Cells Pili, proteins, teichoic acid.
Immune Recognition By Host All outer structures.
Escape From Host Recognition Capsule, M protein.
Antibiotic Sensitivity Peptidoglycan synthetic enzymes.
Antibiotic Resistance Outer membrane.
Motility Flagella.
Mating Pili.
Adhesion Pili.
Functions Of The Bacterial Envelope

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