Allies and Enemies: How the World Depends on Bacteria Read Online Free
Author: Anne Maczulak
Tags: science, Reference, Non-Fiction
bacteria that make these appendages, called O antigens, construct them out of sugars rarely found in nature. As a consequence, protozoa that prey on bacteria do not recognize the potential meal and swim past in search of “real” bacteria.
Archaea seem to be Earth’s ultimate survivors because of the
extreme environments they inhabit. Archaea and bacteria both
belong to the prokaryotes, one of two major types of cells in biology,
the other being more complex eukaryotic cells of algae, protozoa, plants, and animals. Because archaea inhabit extreme environments
that would kill most terrestrial animal and plant life, the archaea are sometimes thought of as synonymous with “extremophile.” The outer
membrane of archaea living in boiling hot springs contain lipid (fat—
like) molecules of 30 carbons or more, larger than most natural fatty
compounds. These lipids and the ether bonds that connect them sta—
bilize the membrane at extremely high temperatures. News stories often tell of new bacteria found at intense pressures 12,000 feet deep
on the ocean floor at vents called black smokers. These hydrothermal
vents spew gases at 480°F, release acids, and reside at extreme pressures, so any organisms living there would truly be a news item. The
organisms living near black smokers are usually archaea, not bacteria.
Archaea also dominate habitats of high salt concentration, such as salt lakes, or places completely devoid of oxygen, such as subsurface sediments. Because of the difficulty of getting at many archaea and their aversion to growing in laboratory conditions, studies on archaea trail
those completed on bacteria.
Some bacteria also survive in the same extreme conditions favored
by archaea. The aptly named Polaromonas inhabits Antarctic Sea ice where temperatures range from 10°F to –40°F by slowing its metabolism until it reproduces only once every seven days. By comparison, E. coli grown in a laboratory divides every 20 minutes. Polaromonas is a psychrophile or cold-loving microbe. Thermus aquaticus is the opposite, a thermophile that thrives in hot springs reaching 170°F by synthesizing heat-stabile enzymes to run its metabolism. Enzymes of chapter 1 · why the world needs bacteria
11
mesophiles, which live in a comfortable temperature range of 40°F to
130°F, unfold when heated and thus lose all activity. Mesophiles include the bacteria that live on or in animals, plants, most soils, shallow waters, and foods. The bacteria that live in harsh conditions that mesophiles cannot endure are the Earth’s extremophiles.
The genus Halococcus , a halophile, possesses a membrane-bound
pump that constantly expels salt so the cells can survive in places like the Great Salt Lake or in salt mines. Barophilic bacteria that hold up under intense hydrostatic pressures from the water above are inexorably corroding the RMS Titanic 12,467 feet beneath the Atlantic.
These barophiles contain unsaturated fats inside their membranes that make the membrane interior more fluid than the fats in other bacterial membranes. Unsaturated fats contain double bonds between some of the carbon atoms in the chainlike fat rather than single bonds
that predominate saturated fats. At pressures of the deep ocean, normal membrane liquids change into the consistency of refrigerated butter, but the special membrane composition of barophiles prevents such an outcome that would render the membrane useless. A later
chapter discusses why red-meat animals store mainly saturated fats and pork and chicken store more unsaturated fats.
The acidophile Helicobacter pylori that lives in the stomach withstands conditions equivalent to battery acid of pH 1 or lower by secreting compounds that neutralize the acid in their immediate surroundings. Even though an acidophile lives in strong acids that would burn human skin, it remains protected inside a microscopic cocoon of
about pH 7. Additional extremophiles include alkaliphiles that live
Archaea seem to be Earth’s ultimate survivors because of the
extreme environments they inhabit. Archaea and bacteria both
belong to the prokaryotes, one of two major types of cells in biology,
the other being more complex eukaryotic cells of algae, protozoa, plants, and animals. Because archaea inhabit extreme environments
that would kill most terrestrial animal and plant life, the archaea are sometimes thought of as synonymous with “extremophile.” The outer
membrane of archaea living in boiling hot springs contain lipid (fat—
like) molecules of 30 carbons or more, larger than most natural fatty
compounds. These lipids and the ether bonds that connect them sta—
bilize the membrane at extremely high temperatures. News stories often tell of new bacteria found at intense pressures 12,000 feet deep
on the ocean floor at vents called black smokers. These hydrothermal
vents spew gases at 480°F, release acids, and reside at extreme pressures, so any organisms living there would truly be a news item. The
organisms living near black smokers are usually archaea, not bacteria.
Archaea also dominate habitats of high salt concentration, such as salt lakes, or places completely devoid of oxygen, such as subsurface sediments. Because of the difficulty of getting at many archaea and their aversion to growing in laboratory conditions, studies on archaea trail
those completed on bacteria.
Some bacteria also survive in the same extreme conditions favored
by archaea. The aptly named Polaromonas inhabits Antarctic Sea ice where temperatures range from 10°F to –40°F by slowing its metabolism until it reproduces only once every seven days. By comparison, E. coli grown in a laboratory divides every 20 minutes. Polaromonas is a psychrophile or cold-loving microbe. Thermus aquaticus is the opposite, a thermophile that thrives in hot springs reaching 170°F by synthesizing heat-stabile enzymes to run its metabolism. Enzymes of chapter 1 · why the world needs bacteria
11
mesophiles, which live in a comfortable temperature range of 40°F to
130°F, unfold when heated and thus lose all activity. Mesophiles include the bacteria that live on or in animals, plants, most soils, shallow waters, and foods. The bacteria that live in harsh conditions that mesophiles cannot endure are the Earth’s extremophiles.
The genus Halococcus , a halophile, possesses a membrane-bound
pump that constantly expels salt so the cells can survive in places like the Great Salt Lake or in salt mines. Barophilic bacteria that hold up under intense hydrostatic pressures from the water above are inexorably corroding the RMS Titanic 12,467 feet beneath the Atlantic.
These barophiles contain unsaturated fats inside their membranes that make the membrane interior more fluid than the fats in other bacterial membranes. Unsaturated fats contain double bonds between some of the carbon atoms in the chainlike fat rather than single bonds
that predominate saturated fats. At pressures of the deep ocean, normal membrane liquids change into the consistency of refrigerated butter, but the special membrane composition of barophiles prevents such an outcome that would render the membrane useless. A later
chapter discusses why red-meat animals store mainly saturated fats and pork and chicken store more unsaturated fats.
The acidophile Helicobacter pylori that lives in the stomach withstands conditions equivalent to battery acid of pH 1 or lower by secreting compounds that neutralize the acid in their immediate surroundings. Even though an acidophile lives in strong acids that would burn human skin, it remains protected inside a microscopic cocoon of
about pH 7. Additional extremophiles include alkaliphiles that live
Readers choose
Mary Jane Maffini
D. Wolfin
Fern Michaels
Kathy Cano-Murillo
Kimberly Raye
Charles Todd
Patrick O'Brian
Alannah Carbonneau
Ray Russell