Ch. 5The Microbial World

Ch. 5“There are 100 million times more bacteria in the ocean than stars in the known universe, and there are a thousand times more viruses than bacteria. Yet we know little about the relationships between microbes and their environment because only one tenth of one percent of the bacteria have ever been cultured.”

We don’t know much

• Venter’s team has found evidence of so many new microbial species that the researchers want to redraw the tree of microbial life... [They] identified more than 400 microbial species new to science...

• One 10-month expedition (in 2007) that sampled the ocean at just 41 locations returned with hundreds of new species able to make millions of proteins that were previously unknown, including tens of thousands that were thought to occur only in higher, multicelled organisms. And this is from only a tiny part of the ocean. Clearly, the microbial web is almost unknown. A vast new frontier of life awaits discovery.

The marine organism that supports all others

• They make up 98% of the biomass of the world’s oceans

• supply more than half the world’s oxygen• major processors of the world's greenhouse gases• About 1.5 million species have been names• Tens of millions of more species may exist• they may hold a cure for cancer and the solutions for

combating known diseases• we know more about distant stars and planets than

we do about the microbes living in our oceans.

Viruses: Living or Non-living?• On the threshold

somewhere in between• Do not contain cells

– Consist of short chain of genetic material

• Parasites• Can only reproduce by

using other cells machinery

Prokaryotes are large dots, viruses are small dots. Viruses significantly outnumber the prokaryotes.

So many viruses . . .• Most abundant life-like particles in the ocean

Why are viruses important in the marine environment?

...ocean waters contain about 4 × 10∼ 30 viruses. Because a marine virus contains about 0.2 fg (femtogram, or 1 quadrillionth) of carbon and is about 100 nm long, this translates into 200 Mt (megaton, 1 million tons) of carbon in marine viruses. If the viruses were stretched end to end they would span 10 million light years (1 light year = 9.5 trillion ∼km). In context, this is equivalent to the carbon in 75 million blue whales ( 10% ∼ ∼carbon, by weight), and is 100 times the distance across our own galaxy. – Suttle, C. A. ∼(2005).

Importance of Viruses

• Infect phytoplankton and bacteria, causing them to burst.

• Bursting cells release contents – dissolved organic matter (DOM)

• Fuels bacteria and microbe growth

• Microbes eaten by zooplankton, which are eaten by larger zooplankton, and so on, up the food chain

Anti-aging?

• The Emiliania huxleyi virus 86, attaches to marine algae

• "For an invading virus, the ability to control when your host will die and ensure your own survival is quite incredible. Essentially the virus hijacks the cell and slows down the ageing process by keeping it healthy for as long as possible. It uses the cell as a kind of factory to replicate itself and eventually takes over completely, killing off the cell."

Prokaryotes

• Smallest and simplest true living organisms

• Oldest forms of life on earth

• No nucleus or most other organelles– One exception is the

ribosome

• Bacteria and Archaea

Bacteria: Friend or Foe?• Prokaryotes• The most diverse domain

on the planet– found from the beaches to

the deepest trenches

• Vital to life on earth– Microbial loop– Flow of energy from

phytoplankton DOM bacteria protozoans zooplankton. Also the cause of diseases

and the spoilage of fish and other food

Cyanobacteria

• Photosynthetic bacteria• 1st photosynthetic

organisms on earth– 3 billion years ago

• Major player in creating the earth’s oxygen atmosphere

Archaea• Simplest, most primitive

forms of life• 3.8 billion years old• Love extreme

environments– Hot sulfur springs, saline

lakes, highly acidic or alkaline environments, deep sea vents

• Found in common marine environment as well

Archaea• Samples from the South

Pacific Ocean– Rare at surface– increased significantly

below depths of 250 m– Below 1000 m, just as

common as bacteria

• One of the most abundant life forms on earth– Sargasso Sea alone: at least

1,800 new species, possibly 50,000!

Protista

• Single celled organisms• eukaryotic• Animal and plant like• Brown algae• Giardia (lovely germ

that causes diarrhea)

Diatoms• Protists• Enclosed by glass-like walls made of

silica• Important primary producers in

cold waters• Glassy shells of diatoms settle on

ocean floor, form diatomaceous ooze.– Diatomaceous earth used in

filters for pools, for clarifying beer, and temp and sound insulators, absorbents (toxic spills) and as abrasives in toothpaste

Diatoms and Oil?• Diatoms produce oil (for

chemical energy and helps them float)

• Diatoms die, settle to bottom of ocean

• Turns into thick sludge, kilometers thick

• Over 1000’s of years, sludgeremains becomes buried by sediments turns into solid rock

• Chemical reactions, high heat & intense pressure turn sludge into oil!

• Then what?

How oil gets to your gas tank

Klaus Kemp’s Diatom Art

Diatom coke bottle?

Dinoflagellates

• Have two unequal flagella

• Important primary producers in warm water.

Bay of Fire

• Bahia Fosforescente, Puerto Rico

• Bioluninescent dinoflagellates

• Pyrodinium bahamense• Regulated by activity of

an enzyme, luciferase, on proteins

• A shock response to movement

La Jolla cove, CA

Protozoans

• Animal like protists• Eukaryotic and

unicellular• Foraminiferans

– Calcium carbonate shell– Thin long strands used

to capture food– The skeletons of

Homotrema rubrum (the red foram), cause the pink sands on Bermudas beaches.

Protozoans: Radiolorans

• Shells are made primarily of glass

• Most are microscopic but can form chains up to 9 ft in length!

Protozoans: Ciliates

• Have hair-like structure called cilia

• Common ciliate is the paramecium

Fungi

• Eukaryotic• Mostly multicellular

– Molds and yeasts are unicellular

• Major decomposers– Especially in mangrove

forests

• Live in symbiotic relations ship with cyanobacteria—this forms lichens