1. INTRODUCTION TO MICROBIAL ECOLOGY

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Oikos (household)
Logos (study)

The word ecology is derived from the greek words…

Ecology

It is a science that explores the interrelationships between organisms and their living and non-living environments.

Microbial Ecology

A science that specifically examines the relationships between microorganisms and their biotic and abiotic environments.

-How microbes interact with other microbes
-How microbes interact with other organisms
-How microbes interact with the non-living world around them

These are considered when studying microorganisms and their ecology

-Nutrient cycling
-Bioenergetics
-Control of man-made pollution
-Global warming
-Animal and plant diseases
-Human microbiome

Microbial Ecology cuts across many present day concerns

Late 1970s

It is the year in which there is a surge of interest in the field of microbial ecology

Xenobiotics

A lot of man-made organics and industrial by-products degrade very slowly in the environment. What do you call these?

“No natural organic compound is totally resistant to biodegradation provided that environmental conditions are favorable”

What does the principle of microbial infallibility say?

Xenobiotic substances

These resist biodegradation or are metabolized incompletely resulting to accumulation in the environment.

-Polychlorinated biphenyls
-DDT
-Plastics

Examples of xenobiotic substances

-Co-inhabitants of the planets
-Their prominent role in global ecology

Microbial ecology stresses the roles of microorganisms as … and …

-Producers
-Consumers
-Decomposers

Microbial roles in nature

Leeuwenhoek

He described the microbes and bacteria

Spallanzani

He attempted to disprove spontaneous generation theory

-Schwann
-Kutzing
-Cagniard-Latour

They independently implicated yeasts in alcoholic fermentations

Pasteur

He demolished the spontaneous generation theory

Haeckel

He introduced the term ecology

Cohn

He described the bacterial endospores and their heat resistance; began work on bacterial taxonomy

Tyndall

He introduced sterilization method by intermittent heating

Koch

He used solid media for isolation and culture of bacteria.

Nicolas-Theodore de Saussure

He reported on the capacity of soil to oxidize hydrogen gas

-Jacques Theophile Schloesing
-Achille Muntz

They observed that ammonium in sewage was oxidized to nitrate when passed through a sand column (nitrification)

C.G. Ehrenberg

He developed theories on the influence of bacteria in the generation of iron deposits in bogs.

Sergei Winogradsky

He isolated and described nitrifying bacteria

Sergei Winogradsky

He discovered microorganisms capable of inorganic chemical oxidation

Martinus Beijerinck

He isolated the first pure cultures of many soil bacteria

Sergei Winogradsky

He developed a model system for growing anaerobic photosynthetic and microaerophilic bacteria

Martinus Beijerinck

He developed the enrichment culture

Sergei Winogradsky

He described anaerobic nitrogen fixation

Martinus Beijerinck

He reported on symbiotic and non-symbiotic N-fixation

Cyanobacteria

In the winogradsky column, these microorganisms live in the water part.

Sulfate-reducing bacteria

In Winogradsky column, these microorganisms live in the highest concentration of sulfide.

Heterotrophic bacteria

In WC, which among the two lives near the oxygenated area? Heterotrophic bacteria or Green sulfur bacteria?

Mud area

Which part of the WC do the high sulfide microorganisms survive?

Microorganisms

These were the first living organisms on earth

3.85 billion

Microbes existed more than … years ago.

Atmospheric methane and carbon dioxide

Before, living microorganisms were assimilating carbon into organic molecules from …

James Lovelock (1979)

Who proposed the Gaia Hypothesis?

Gaia Hypothesis

It states that the earth acts like super organism and that through the biochemical activities of its biota, its physico-chemical characteristics are self-regulated so that they are maintained in a favorable range for life.

-Oparin and Haldane
-Miller and Urey

… and … proposed the idea of the gradual chemical evolution toward life. The experimental support was provided by … and …

Fox (1965)

He demonstrated the formation of thermal proteinoids by the moderated heating of amino acid mixtures.

Thermal Proteinoids

These exhibit self-replicating tendency, spontaneously aggregating into microspheres (protobionts or progenotes)

-Mitochondria and chloroplasts contain DNA
-70S ribosomes in the mitochondria and chloroplasts
-Presence of hydrogenosomes
-Antibiotic specificity
-Eukaryotic nucleus contains genes derived from bacteria

Evidences of Endosymbiotic Hypotheses

Prokaryotes: Absent
Eukaryotes: Present with nuclear membrane

NUCLEUS
Prokaryotes:
Eukaryotes:

Prokaryotes: Absent
Eukaryotes: Present in variety of forms

ORGANELLES
Prokaryotes:
Eukaryotes:

Prokaryotes: Single closed loop, almost naked strand, very little proteins
Eukaryotes: Multiple chromosomes in nucleus, structural protein associated with DNA

DNA STRUCTURE
Prokaryotes:
Eukaryotes:

Prokaryotes: When present, dissolved in cytoplasmic membranes
Eukaryotes: When present, dissolved in chloroplast membranes

CHLOROPHYLL
Prokaryotes:
Eukaryotes:

Prokaryotes: Smaller than eukaryotic ribosomes, free in cytoplasm
Eukaryotes: Larger, free or bound to membrane

RIBOSOMES
Prokaryotes:
Eukaryotes:

Prokaryotes: Generally present, complex chemical compositions
Eukaryotes: Present in some types, complex chem. composition

CELL WALLS
Prokaryotes:
Eukaryotes:

Prokaryotes: Rotating movements
Eukaryotes: Whipping movement

FLAGELLA
Prokaryotes:
Eukaryotes:

Prokaryotes: Absent
Eukaryotes: Present in some cells

CILIA
Prokaryotes:
Eukaryotes:

Prokaryotes: Fission
Eukaryotes: Meiosis

REPRODUCTION
Prokaryotes:
Eukaryotes:

Prokaryotes: Bacteria, Archaea
Eukaryotes: Plants, Animals, Fungi, Protists

EXAMPLES
Prokaryotes:
Eukaryotes: