90646_CH05_0087_rev2.qxd 12/3/10 1:39 PM Page 87 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Bacteria:NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION The First Microbes 5 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Looking Ahead This picture shows the hot spring Devil’s Bath (Wai-O-Tapu Thermal Bacteria are among the most successful organisms on Earth. Over the billions of years of their Wonderland) in Rotorua, © Jones &existence, Bartlett they Learning, have evolved LLC to occupy every conceivable© Jones niche on& BartlettEarth; indeed, Learning, they influ- LLCNew Zealand. Thermal ence almost everything we experience. In this chapter, we shall get to know the bacteria as pools like this represent NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTIONthe harsh conditions we examine their structures and activities. under which the earliest On completing this chapter, you should be able to . of Earth’s microorganisms • appreciate the enormous span of time in which bacteria have existed on Earth and evolved and flourished. understand their contributions to the formation of the world as we know it; • summarize the© various Jones forms & Bartlett of known Learning, bacteria and LLCdefine many of the submicroscopic© Jones & Bartlett Learning, LLC structures associatedNOT FORwith a SALEbacterial OR cell; DISTRIBUTION NOT FOR SALE OR DISTRIBUTION • describe the process by which bacteria reproduce, and grasp the significance of the frequency of bacterial replication; • identify some of the environments in which bacteria thrive, and recognize the differ- © entJones types & of Bartlett cultivation Learning, techniques LLC available for growing bacteria© Jones in the laboratory; & Bartlett Learning, LLC •NOToutline FOR several SALE important OR DISTRIBUTION groups of bacteria in order to appreciateNOT their FOR diversity; SALE and OR DISTRIBUTION • identify the importance of bacteria in the disease process and briefly summarize some of the mechanisms of bacterial disease and body resistance. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 87 © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. 90646_CH05_0087_rev2.qxd 12/3/10 1:39 PM Page 88 88 CHAPTER 5 Bacteria: The First Microbes The Earth came into being an almost incomprehensibly distant 4.5 billion years © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLCago. For the first several millions of years of its existence, Earth was a ball of molten NOT FOR SALE OR DISTRIBUTIONrock. Then, as millennia passed,NOT FOR a thin SALE crust formed OR DISTRIBUTION over the hot core, and violent vol- canic activity filled the days and nights. Now the Earth was awash with energy: There was radiation from the sun, lightning from intense electrical storms, and heat from radioactive decay and the ever-present volcanic eruptions. In the incessant rain and © Jonesthe tropically& Bartlett warm Learning, oceans, organic LLC molecules were forming—amino© Jones & acids, Bartlett proteins, Learning, LLC NOT FORnucleotides, SALE andOR carbohydrates—the DISTRIBUTION stuff that one day wouldNOT compose FOR SALE living ORthings. DISTRIBUTION For its first billion years, the Earth was as barren of life as the surface of the moon is today. Then, about 3.5 billion years ago, microscopic cells, the first living things, came into being. Although scientists are uncertain how these cells arose, they are rea- sonably sure that these first life forms were bacteria. The ancient bacteria (like the © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC modern forms) were tiny, single-celled creatures, with little evidence of internal struc- prokaryoteNOTA microorganism FOR SALE in ORture. DISTRIBUTION Organisms like these are called prokaryotesNOT FOR, a name SALE that OR reflects DISTRIBUTION the absence of the domain Bacteria or Archaea a nucleus (karyo is Greek for “nut” [or nucleus], and pro means “primitive”). Chapter 2 composed of single cells having a single chromosome but no cell compares prokaryotes and eukaryotes more fully. nucleus or other membrane- Bacteria (or prokaryotes) were the only inhabitants of the Earth for over 2 billion © Jonesbound & Bartlett compartments. Learning, See also LLCyears, nearly half of the© planet’s Jones existence. & Bartlett Then, Learning, about 1.5 LLC billion years ago, the eukaryote. NOT FOR SALE OR DISTRIBUTIONeukaryotes evolved, as FIGURENOT 5.1 FORillustrates. SALE TheseOR DISTRIBUTION organisms, typified by protozoa, eukaryote An organism whose fungi, plants, and animals, have larger cells, with nuclei and complex internal struc- cells contain a cell nucleus with multiple chromosomes, a nuclear tures. Although the eukaryotes were larger organisms, the bacteria were not threat- envelope, and membrane-bound ened because by that time bacteria had the advantage—they were well-established compartments. and in full swing. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC And what a group they were: Growing wildly in the oxygen-free atmosphere of NOT FOREarth, SALE the ancient OR DISTRIBUTIONbacteria chemically combined hydrogenNOT with FOR the carbon SALE of carbonOR DISTRIBUTION dioxide to form methane (not unlike what we find in a swamp today). Then the photo- cyanobacterium synthetic bacteria evolved. These forms are called cyanobacteria (or blue-green algae (pl. cyanobacteria) An oxygen- in the older literature). Cyanobacteria used their chlorophyll pigments in the process producing, pigmented bacterium occurring© in Jones unicellular & and Bartlett ofLearning, photosynthesis LLC to capture light energy© Jones and produce & Bartlett carbohydrates Learning, as energy- LLC filamentousNOT forms FOR that carriesSALE ORstorage DISTRIBUTION compounds. In so doing, they playedNOT a FOR decisive SALE role inOR Earth’s DISTRIBUTION development out photosynthesis. because photosynthesis dramatically increased the atmospheric concentration of oxy- gen from 1% to the current 21%. More than any other organisms on Earth, cyanobac- teria were catalysts for the oxygen-based chemistry that now pervades earthly life. All the contemporary bacteria developed from the evolutionary experiments that © Jones & Bartlett Learning, LLCMother Nature performed© on Jones these ancient& Bartlett forms. Learning, And the results LLC have been spectac- NOT FOR SALE OR DISTRIBUTIONular, for modern bacteriaNOT have FOR come SALE to occupy OR every DISTRIBUTION conceivable niche on Earth. Time of humans © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT TimeFOR of SALEanimals OR DISTRIBUTION Time of eukaryotes Oldest Origin of Earth Time of bacteria Earth rocks © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 5 billion 4 billion 3 billion 2 billion 1 billion Now years ago years ago years ago years ago years ago FIGURE 5.1 The Bacteria on Earth. This timeline shows how long various groups of organisms have existed on Earth. The bacteria have been in existence for a notably longer period of time than any other group, particularly humans. They have adapted well to Earth’s varied conditions simply because © Jones & Bartlett Learning, LLCthey have had the longest opportunity© Jones to adapt. & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. 90646_CH05_0087_rev2.qxd 12/3/10 1:39 PM Page 89 Looking Ahead 89 Every crack, every crevice, every cranny—whether at the bottom of a 6-mile deep Pacific © Jones & Bartlett Learning, LLC © Jones trench,& Bartlett at the Learning, pinnacle of LLC Mount Everest, or in the blazing desert of the Sahara— NOT FORcontains SALE someOR DISTRIBUTION sort of bacterial life. A single pinch of NOTrich soil FOR contains SALE over OR a billionDISTRIBUTION bacteria. Indeed, a handful of that same soil contains more bacteria than all the peo- ple who have ever lived on planet Earth. It should not be surprising that bacteria occupy a critical place in the web of life. Many bacterial species© makeJones major & Bartlett contributions Learning, to the mineral LLC balance of the world © Jones & Bartlett Learning, LLC by metabolizing the NOTnutrients FOR in SALEfreshwater, OR marine,DISTRIBUTION and terrestrial environments. NOT FOR SALE OR DISTRIBUTION The bacteria residing in soil influence the Earth’s ecology by breaking down the remains of all that die and recycling the elements. And certain bacterial species do what few other species of organisms on Earth can do—they trap nitrogen from the air and con- vert it to substances used by plants to make protein, which ultimately winds up on © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC our plates as grains, meat, and dairy products. InNOT industrial FOR and SALE biochemical OR DISTRIBUTION