[WIP] 11 The Diversity of Bacteria and Archaea

WORK IN PROGRESS

6,000

Prokaryotes are the most diverse in terms of shape, metabolism, habitats

Out of a million species estimated to exist, only [__] are identified

• most not isolated

• metagenomics and new molecular techniques aid in discovery and characterization » can make predictions from genes

metabolic diversity

Ability to use different substances as carbon and energy sources

Allows microbes to live in diverse environments

single

Members of the domain Bacteria and Archaea BOTH:

• are [__]-celled organisms

• lack membranes and membrane-bound organelles

• rigid cell walls

  • peptidoglycan in Bacteria

  • pseudopeptidoglycan in Archaea

• have similar shapes

• mean by flagellum

• multiply by binary fission

however, Archaea differ in how they can survive in extreme environments

methanogens

Archaea genera whose members generate methane from CO₂ and hydrogen from environment.

The exception to Archaea thriving in extreme environments

Extreme Halophiles

Archaea genera whose members thrive in highly salty environments

Extreme Thermophiles

Archaea genera whose members thrive in high temperature environments (typically boiling)

Bacteria

Members of this domain are commonly responsible for human infections

nutrients

Microbes can be found in every type of habitat that supports every life.

i.e., microbes can exist so long as they have the required [__] for growth and can withstand the environmental conditions

• extreme environments

• terrestrial environments (soil, air)

  • water evaporated in the air has microbes in them

• aquatic environments (open sea, lakes, streams, ponds, marshes and wetlands, hot springs, arctic ice sheets)

in addition to microbes living in humans, they can also be associated with insects, plants and animals

Thermus aquaticus

Extreme hot environments include:

• boiling pools

• hot springs

• hydrothermal vents → can be 120C (250F)

  • worms with bacteria in folds

  • Taq polymerase found here in [__]

red bacteria

Extreme cold environments include:

• glaciers and snow fields

  • can find [__] here » photosynthetic and produces red pigment

• Antarctic ice sheets → 12C (10F)

Halobacterium

Extreme high salt environments include:

• Great Salt lake, Dead Sea, soda lakes

  • where extreme halophiles reside (mostly in 5-32% salt)

  • bacteria, algae, protozoa typically require 9% salt conc.

• Owens lake (Sierra Nevada)

  • reddish color due to the salt-loving bacteria [___]

Anoxic extremophiles

Extreme highly basic (alkaline, hypersaline) environments include:

• Mono Lake in California

  • has [__]

Sulfolobus

[___] is a bacteria that thrives in sulfuric-rich, acidic hot springs and soils

• oxidize sulfur to sulfuric acid

• requires pH between 1-6

• grow above 50C to 85C

Sheathed bacteria

Bacteria residing in aquatic environments lack steady supply of nutrients.

Mediates this by forming chains of cells within a tube

• sheaths protect an help bacteria attach to solid objects

• Gram-negative bacteria

eg. Sphaerotilus, Leptothrix

Prosthecate bacteria

Bacteria residing in aquatic environments lack steady supply of nutrients.

Mediates this by having extensions that provide increased SA for nutrient absorption; some extensions also allow attachment

eg. Caulobacter

Bdellovibrio

Bacteria residing in aquatic environment that is a highly motile Gram-negative curved rod

Preys on other bacteria, such as E. coli and other Gram-negatives

Staphylococcal

Animal bodies provide a variety of ecological habitats for bacteria

The skin is one of them

» typically dry; inhospitable to many microbes

» [___] species → significant component of skin flora

Bifidobacterium

Animal bodies provide a variety of ecological habitats for bacteria

The Mucous membranes (Respiratory, genitourinary, intestinal tracks) are one of them

» Bacteriodes responsible for mouth, GI and genital tract infections

» [__] responsible for GI tract infections

human

Some of the normal bacterial flora that are associated with the [__] microbiome are:

1. a

2. b

3. c

4. d

5. e

6. f

Bioluminescent bacteria

Bacteria that have symbiotic relationships with:

• certain fish and squid (helps with camouflage and confuse predators and prey)

• other animals for food and protection

eg. Photobacterium, Vibrio

aphids

These organisms live in association with fungi:

• ants »

• [__] »

Agrobacterium

Bacteria that associate with plants.

Produces plant tumors to gain nutrients, which are often fatal to the plant

Rhizobium

Bacteria that associate with plants.

Has a mutually beneficial relationship with legumes → fixes nitrogen to be used as a nutrient source for plant