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Unit 1: Introduction to Environmental
Microbiology
Introduction
● History of Environmental Microbiology
● Interrelations with other fields of Microbiology
● Modern Environmental Microbiology
● Types of Microbes (Viruses, Bacteria, Fungi, Algae, Protozoa)

What is Environmental Microbiology?
It has two components:
1
...
Microbiology
Definition: study of applied aspects of microorganisms on environment and human
activities, health, and welfare
The impact on human activities may be:
a
...
microbial diseases
b
...
through action of animals, plants, and ecosystems

Microbial Actions May be:

a
...
Detrimental
● Transmission of bacterial & viral pathogens of human

History of Environmental Microbiology
In 1970, environmental microbiology emerged as a new science
Microbial ecology: interaction of microbes with the environment
→Includes air, water, and soil

Various Events Which Occurred in 1970
Emergence of water-borne and food-born pathogens (threat to human and animal
diseases)
Contamination of surface and groundwater (organic and inorganic chemicals)
Discovery of various protozoa
Contamination of imported food
Chemical pollutants:
a
...
Economic impact - high cost of clean up

Bioremediation

Relationship with Other Fields of Microbiology
Aquatic microbiology

Soil microbiology

Biotechnology

Diagnostic microbiology

Occupational Health/Infection Control

Waste bioremediation

Aeromicrobiology

Water Quality

Industrial microbiology

Food microbiology

Modern Environmental Microbiology
1
...
Biogeochemistry
● Carbon cycle
● Nitrogen
● Sulfur Cycle
● Control of loss of fixed nitrogen

3
...
Aeromicrobiology
● Collection and detection of pathogens in the air environment
● Movement of microbes in the air
5
...
Food quality
● Organic & inorganic contamination
● Detection and identification of pathogens
● Elimination or control of pathogens
7
...
Wastewater treatment
● Sewage water treatment
● Biodegradation
9
...
Biotechnology
● Detection of pathogens

Microbiology Diversity in the Environment
Two types of microbes:
a
...
Cellular: two types
i
...
Eukaryotes
● Fungi
● Algae
● Protozoa

Introduction to Viruses
In a biological sense, a virus is:

● Any acellular entity (not organism) having both nucleic acid (either DNA, or RNA,
never both) surrounded by capsid protein and has capability to cause infection in
living cells or organisms
Viruses are NOT living things
Viruses lack the ability to reproduce independently
● Require hosts to multiply
● Replicates only in living cells
Viruses
...
For example, viruses
...

-

do not grow

-

do not respond to stimuli

-

have no metabolic activity

-

are unable to replicate without a host cell

All viruses are potentially infectious

Hosts of Viruses
All living organisms are infected by viruses:
-

Animal viruses

-

Human viruses

-

Plant viruses

-

Bacterial viruses (Bacteriophages)

-

Insect viruses (Entomoviruses)

Algal viruses (Phycoviruses)
Fungal viruses (Mycoviruses)

Viroids
-

Naked ssRNA molecules, no capsid protein

-

They are not viruses

-

1/10 of the size of the smallest virus

-

300-400 nucleotides long

Known to cause serious disease in plants
● Potato spindle tuber disease
● Citrus exocortis
● Carnation stunt disease

Prions
-

Protein in nature

-

Associated with nervous tissue

-

Cause diseases in animals and human beings, not in plants

Examples
● Kuru disease
● Scrapie disease of sheep
● Mad cow disease

Bacteria
Unicellular, prokaryotic cell, reproduce by binary fission

This group includes
Archaebacteria
-

Differ from true bacteria in that:
-

their rRna is 16s

-

Cell wall does not have peptidoglycan

-

The cell membrane is a single layer of glycero-hydrocarbon-glycerol
chains instead of bi-layer of phospholipids

-

Their ribosomes are insensitive to antibiotics

-

Live in extreme environments

True Bacteria
-

Read above

Cyanobacteria
-

They are also known as blue-green algae, but are prokaryotes

-

They are autotrophic

-

They have chlorophyll-a pigments and can perform photosynthesis

-

They also fix atmospheric nitrogen
Examples:
● Nostoc
● Anabaena
● Oscillatoria

Rickettsia, Mycoplasma, Chlamydia
-

All are prokaryotes

-

The Rickettsiae and Chlamydiae are intracellular parasites of eukaryotes

-

Rickettsiae are tiny rods transmitted by arthropods and multiply only in living
tissue

-

The Chlamydiae are among the smallest bacteria

-

Mycoplasma are associated with lung disorders

Myxobacteria
-

They are also called fruiting bacteria as they form fruit bodies

-

Have multicellular specialized like slime molds

-

Most complex in behavior

Actinomycetes
-

They are gram positive prokaryotes

-

They are filamentous bacteria

-

Mostly soil living

-

Most of these produce antibiotics
-

Ex

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