Evolutionary Microbiology

Chapter 6. Bacteria – Planet Conqueror

Jong-Soon Choi

Chungnam National Univ. GRAST

University of Science and Technology

Korea Basic Science Institute

104

Characteristics of Bacteria (4U)

-Unicellular

-Ubiquitous

-Uncountable number

-Utmost recycler

Single celled organisms

Very small

Need a microscope to see

Can be found on most

materials and surfaces

Unicellular Filamentous

The largest procaryoteThiomargarita namibiensis

(Source: www.google.com) 105

Characteristics of Bacteria (4U)

-Unicellular

-Ubiquitous

-Uncountable number

-Utmost recycler

Soil bacteria (a teaspoon of compost)

~100 Billion

Acidic hot spring (~100℃)

Radioactive waste (D. radiodurans)

Sea water (Sargasso Sea)

Earth crust (2 km deep)

Human body (10 times of Human cells)

D. radiodurans(Source: www.google.com)

106

Characteristics of Bacteria (4U)

-Unicellular

-Ubiquitous

-Uncountable number

-Utmost recycler

Soil bacteria (a teaspoon of compost)

~100 Billion

Acidic hot spring (~100℃)

Radioactive waste (D. radiodurans)

Sea water (Sagasso Sea)

Earth crust (2 km deep)

Human body (10 times of Human cells)

Human bacterial flora (Source: www.google.com) 107

Characteristics of Bacteria (4U)

-Unicellular

-Ubiquitous

-Uncountable number

-Utmost recycler

More than 50% biomass

~40 M bacteria/g soil

1 M bacteria/ml fresh water

~10 times of bacteria cells on human

A total of 5x1030 bacteria on Earth

(Source: www.google.com) 108

Characteristics of Bacteria (4U)

-Unicellular

-Ubiquitous

-Uncountable number

-Utmost recycler

Decomposer of food chain

Continuous recycling of materials

* If they are gone, what will happen?

What would happen to

the world if all bacteria

were gone suddenly?

-Tiny recycler

-Bacteria and the body

(Source: www.google.com) 109

History of Bacteriology

-Antonie van Leewenhoek (1676) observed first bacteria using a single-lens

microscope. He called them "animalcules".

-Christian Gottfried Ehrenberg (1828)

introduce the name bacterium, derived from

the Greek word bacterion, meaning "small staff".

RobertHooke’sMicroscope &Cork cells(1696)

(Source: www.google.com) 110

History of Bacteriology

-Louis Pasteur (1859) demonstrated the fermentation by the growth

of microorganisms, not due to spontaneous generation.

Swan neck experiment by Pasteur

“Against Spontaneous Generation”

“Spontaneous Generation”

The generation of life from

nonliving matter was introduced by

Aristotle 350 BC

(Source: www.google.com) 111

History of Bacteriology

-Robert Koch (1905), a pioneer in

medical microbiology and worked

on cholera, anthrax and

tuberculosis, awarded a Nobel

Prize by germ theory & Koch’s

postulates

Koch’s Postulates

1. Pathogen must be

ASSOCIATED with disease

2. Pathogen must be

ISOLATED by pure culture

3. INOCULATION of the isolate

must reproduce same

symptom

4. Pathogen must be

REISOLATED from inoculate

(Source: www.google.com) 112

History of Bacteriology

-Paul Erlich (1908) developed the first antibiotic by changing dyes that

selectively stained Treponema pallidum. He was awarded a Nobel Prize by the

immunological work, being the basis of the Gram stain and the Ziel-Neelsen

stain

Gram(+) bacteria : thick peptidoglycan

Gram (-) bacteria : very thin peptidoglycan, outer membrane

(Source: www.google.com) 113

History of Bacteriology

-Carl Woose (1977) recognized that the archaea have a separate line of

evolutionary descent from bacteria. This new phylogenetic taxonomy was

based on the sequencing of 16S ribosomal RNA, and divided prokaryotes into

two evolutionary domains, as part of the three-domain system.

Stromatolite 3.6BY

(Source: www.google.com) 114

Bacterial Morphology

Medical Microbiology Outlines

by Morphology

(Source: Wikipedia) 115

Bacterial StructurePlasmid : small independent

pieces of DNA, horizontal gene

transfer, antibiotic-resistant,

virulence factor

Ribosomes : the site of protein

synthesis

Pili : bacterial conjugation

Capsule : impermeable structure,

protein & polysaccharides,

antigenic, biofilm

Flagella : whip-like structure for

bacterial motility

In Cytoplasm : cytoskeleton, gas

vesicles, carboxysomes,

endospore, etcCell Wall : peptidoglycan layer composed of

polysaccharide chains cross-linked by unusual

peptides. D-alanine / penicilin (D-Ala analog)(Source: Wikipedia)

116

Bacterial Classification

(Source: Wikipedia) 117

Bacterial Metabolism

Nutritional

type

Source of

energySource of carbon Examples

Phototrophs Sunlight

Organic compounds

(photoheterotrophs) or

carbon fixation

(photoautotrophs)

Cyanobacteria,

Green sulfur

bacteria, Chloroflexi,

Purple bacteria

LithotrophsInorganic

compounds

Organic compounds

(lithoheterotrophs)

or carbon fixation

(lithoautotrophs)

Thermodesulfobacteria,

Hydrogenophilaceae,Nitrospirae

OrganotrophsOrganic

compounds

Organic compounds

(chemoheterotrophs) or c

arbon fixation

(chemoautotrophs)

Bacillus, Clostridium,Enterobacteriaceae

Phototroph

Cyanobacteria

Lithotroph

Sulfur-reducing

Bacteria

Organotroph

Bacillus anthrax

(Source: www.google.com) 118

Competition between Bacteria

SRB

Sulfur

Reducing

Bacteria

MB

Methanogenic

Bacteria

(Source: www.google.com) 119

Competition between Bacteria

Anaerobic bacteria : Sulfur-reducing bacteria & Methanogenic bacteria

SRB outcompetes MB!! Then, where do MB live??

(Source: www.google.com) 120

Bacterial GeneticsAvirulent R colony and Virulent S colony

of S. pneumoniae

Griffith’s Bacterial Transformation (1928)

Griffith Experiment

-F. Griffith (2918)

suggested that bacteria are

capable of transferring

genetic information through

a process known as

“transformation”.

-Griffith’s findings were

followed by research in the

late 1930s and early 40s

that isolated DNA as the

material is the genetic

information.

(Source: www.google.com) 121

Bacterial Genetics

DNA is Identified as the ”Transforming

Principle” (Avery, 1944)

H&C Proved that transforming element is

DNA (1944) (Source: www.google.com) 122

Bacterial Genetics

Transformation

Directly acquired DNA from another cells

Conjugation

DNA transfer by cell-

to-cell contact (e.g.,

pili)

Transduction

Gene transfer via

bacteriophage

(Source: www.google.com) 123

Bacterial Genetics

E. coli Long-term Evolution

After 30,000 generation, one

population evolved ability to use

citrate (Salmonella-like)

Cit+ and Cit- types coexist!

Experimental Evolution: 50,000

Generations in the Life of E. coliDr. Richard Lenski

Michigan State University

(Source: www.google.com) 124

Bacterial Disease

(A) Tetanus

(파상풍)

(B) Cholera

(dehydration)

(C) Syphilis

(cranial

deformation)

(D) Leprosy

(Hansen’s disease)

(E) Tuberculosis (결핵)

(Source: www.google.com) 125

Bacterial Disease

Oriental rat flea (Xenopsylla cheopis)

is a parasite of rodents and a primary

vector of bubonic plaque.

Unit 731 and Japanese Imperial

Army’s Biological Warfare Program

(1933~1945). 850 victims in 1943.

Yersinia pestis

(Source: www.google.com) 126