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Solving Deep Microbial Mysteries
Dr. Karla Heidelberg from the University of Southern California views vent protists with the modified environmental scanning electron microscope (eSEM) in a lab aboard the R/V Atlantis. It is the first time that a scanning electron microscope has been out to sea! Unlike more traditional light microscopes, this instrument uses backscattered electrons to produce super-detailed images of the surface of very small organisms.
Microbes -- those tiny, single-celled organisms shrouded in mystery -- are really quite monumental. Although we can't see them, they live everywhere, and they far outnumber us. And without them, we would be dead!
Microbes live high in the atmosphere, all the way down to the bottom of the sea, and even deep within the Earth's crust.
Microbes live inside us, too. In fact, there are more microbes in your intestines than there are cells in your body, and you have about 100 trillion cells!
Although some microbes are capable of making us sick and even killing us, we could not inhabit Earth without them. Microbes make it possible for us to breathe and eat. Without microbes, much of the carbon, nitrogen, oxygen, sulfur, phosphorus, and other chemical elements that life on the planet needs to survive, would be locked up in minerals and gases.
So, What Is a Microbe?
The word "microbe" entered the English language in
1881. It's Greek in origin, derived from "mikros" meaning
small, and "bios" meaning life.
Most microbes are single-celled organisms that measure less than 0.1 mm and are invisible to the naked eye. Most live independently, but some form groups of cells called colonies that may become large enough to see.
Microbes come in a fascinating array of shapes and sizes and perform a diversity of functions. There are archaea, bacteria, fungi, protists, and viruses. Even smaller than viruses are viroids and prions, which are both infectious agents about which little is known.
The Microbial Focus of Extreme 2008
The hydrogen sulfide and other chemicals that rocket out of hydrothermal vents would be poisonous to most organisms. Yet exotic animals flourish in this harsh environment thanks to unique adaptations and special relationships with the tiniest life at the vents: bacteria.
Thick mats of bacteria cover the seafloor and volcanic rock, and snow-like blooms of bacteria may also occur, causing a temporary "white-out" at the vents.
Zoarcid fish prey on organisms such as deep-sea shrimp, which, in turn, depend on bacteria for food. Still other vent dwellers, such as tubeworms and deep-sea clams, harbor bacteria inside their bodies to make food for them.
Other microscopic organisms also prey on bacteria, yet neither their roles in the food chain nor their genetic diversity have been deeply probed -- until now.
"For many years, the vents have been explored with little to no attention to viruses and protists," says Dr. Craig Cary, professor of marine biosciences at the University of Delaware, and chief scientist for Extreme 2008.
"Yet because these organisms eat bacteria, they have the most dramatic effect on the bacterial communities that support the vent system. Our research programs are among the first to focus on these remarkable scavengers," Dr. Cary notes.
Learn more about the vent protists from Dr. Dave Caron and his research team at the University of Southern California, and about the viruses at the vents from Dr. K. Eric Wommack and his research group at the University of Delaware.
What is a mysterious little bundle of genetic material all wrapped up in a protein shell? Yep, it's a virus! It can’t grow or reproduce unless it is inside another organism’s cells. Read all about the University of Delaware's research on the viruses of the vents!
The protists include an
intriguing array of microorganisms, including the animal-like protozoa that
inhabit vent sites. Read all about the University of Southern California's
research on these tiny hunters and their role in the vent food chain.
What makes it a microbial world? Get the answer straight from the microbe's mouth on this Web site by the Delaware EPSCoR program.
It could be because microbes were the first forms of life on the planet, and ever since then they've been flourishing and taking advantage of every possible niche and source of food. Or it could be because they are even more numerous than the stars. Or it could be because we depend on them for much of the air we breathe and the food we eat — we even need their help to digest it!
Even though a few of them are capable of killing us, the Earth without microbes would be a completely uninhabitable place . So let's give credit where credit is due — all hail the microbes!
