Presentation on theme: "I. Bacteria Introduction Various functions/roles of bacteria"— Presentation transcript:
1 I. Bacteria Introduction Various functions/roles of bacteria Diseases caused by bacteriaClassification of bacteriaMetabolismStructure of bacteriaReproductionImage Source:Bacteria are often maligned as the causes of human and animal disease (like this one, Leptospira, which causes serious disease in livestock). However, certain bacteria, the actinomycetes, produce antibiotics such as streptomycin and nocardicin; others live symbiotically in the guts of animals (including humans) or elsewhere in their bodies, or on the roots of certain plants, converting nitrogen into a usable form. Bacteria put the tang in yogurt and the sour in sourdough bread; bacteria help to break down dead organic matter; bacteria make up the base of the food web in many environments.Bacteria are of such immense importance because of their extreme flexibility, capacity for rapid growth and reproduction, and great age - the oldest fossils known, nearly 3.5 billion years old, are fossils of bacteria-like organisms.Image Source:
2 A. Introduction Thought to cause human and animal disease actinomycetes, produce antibiotics such as streptomycin and nocardicin;Some live symbiotically in the guts of animals (including humans-ecoliLeptospira-disease in livestock
3 Intro. Cont. Bacteria put the tang in yogurt Put the sour in sourdough breadbreak down dead organic matterbacteria make up the base of the food web in many ecosystemsextreme flexibility, capacity for rapid growth and reproduction, and great age-they have been around a very long time!nearly 3.5 billion years old-are fossils of bacteria-like organisms.
4 B. Functions/Roles of Bacteria Nitrogen fixationa. convert nitrogen into a usable form on the roots of plantsRecycling of nutrientsa. break down dead organic matterFoodsa. Used in food to put the tang in yogurt and the sour in sourdough breadMedicinesa. produce antibioticsCause diseaseGenetic Engineering!!!!
5 C. Diseases Caused by Bacteria Image Source: Biggs, Alton, Kathleen Gregg, Whitney Crispen Hagins, and Chris Kapicka. Biology: The Dynamics of Life. Columbus: Glencoe/McGraw Hill, 2002.Table 18.2 p. 511
6 D. Classification of Bacteria Kingdoma. MoneraPhylums:ArchaebacteriaEubacteria
7 3. Archaebacteria Known as the extremophiles Live in extreme environments that would kill other microbesAlso know as the ancient bacteria
8 4. Extreme Thermophiles Extreme Thermophiles High temperatures Sulfur Hot potsHydrothermal ventsHigh temperaturesSulfurThermus Aquaticus –taq polyermase used in PCR21Image Sources:1.2.Extreme thermophiles require a very high temperature (80 degrees to 105 degrees) for growth. Their membranes and enzymes are unusually stable at high temperatures. Most of these Archaea require elemental sulfur for growth. Some are anaerobes that use sulfur as an electron acceptor for respiration in place of oxygen. Some are lithotrophs that oxidize sulfur as an energy source. Sulfur-oxidizers grow at low pH (less than pH 2) because they acidify their own environment by oxidizing So (sulfur) to SO4 (sulfuric acid). These hyperthermophiles are inhabitants of hot, sulfur-rich environments usually associated with volcanism, such as hot springs, geysers and fumaroles in Yellowstone National Park, and thermal vents ("smokers") and cracks in the ocean floor. Sulfolobus was the first hyperthermophilic Archaean discovered by Thomas D. Brock of the University of Wisconsin in His discovery, along with that of Thermus aquaticus in Yellowstone National Park, launched the field of hyperthermophile biology. (Thermus aquaticus,source of the enzyme taq polymerase used in the polymerase chain reaction (PCR), is a Bacterium which has an optimum temperature for growth of 70 degrees.) Sulfolobus grows in sulfur-rich, hot acid springs at temperatures as high as 90 degrees and pH values as low as 1. Thermoplasma,also discovered by Brock, is a unique thermophile that is the sole representative of a distinct phylogenetic line of Archaea. Thermoplasma resembles the bacterial mycoplasmas in that it lacks a cell wall. Thermoplasma grows optimally at 55 degrees and pH 2. Interestingly, it has only been found in self-heating coal refuse piles, which are a man-made waste.Hot spring (yellow patches are mats of microbial growth)
9 d. Examples of Extremophiles Thermophileshigh temperature (80 degrees to 105 degrees C) for growthSulfur-oxidizers grow at low pH (less than pH 2) because they acidify their own environment by oxidizing S (sulfur) to H2SO4 (sulfuric acid).inhabitants of hot, sulfur-rich environments associated with volcanism, such as hot springs, geysers etc.Yellowstone National Park, and thermal vents ("smokers") and cracks in the ocean floor examplesImages source:
10 e. Extreme Methanogens Methanogens live Natural Gas marshes lake sedimentsdigestive tractsmammals (cows)sewage disposal plants.Natural GasImage source:Methanogens live in oxygen –free environments and produce methane gas. Live in marshes, lake sediments, digestive tracts of some mammals (cows), and sewage disposal plants.Methanogens have an incredible type of metabolism that can use H2 as an energy source and CO2 as a carbon source for growth. In the process of making cell material from H2 and CO2, the methanogens produce methane (CH4) in a unique energy-generating process. The end product (methane gas) accumulates in their environment.Methanogen metabolism created most the natural gas (fossil fuel) reserves that are tapped as energy sources for domestic or industrial use.Methanogens are normal inhabitants of the rumen (fore-stomach) of cows and other ruminant animals. A cow belches about 50 liters of methane a day during the process of eructation (chewing the cud). Methane is a significant greenhouse gas and is accumulating in the atmosphere at an alarming rate. When rain forests are destroyed and replaced by cows, it is "double-hit" on the greenhouse: (1) less CO2 is taken up by removal of the autotrophic green plants; (2) additional CO2 and CH4 are produced as gases by the combined metabolism of the animal and methanogens.Methanogens represent a microbial system that can be exploited to produce energy from waste materials. Large amounts of methane are produced during industrial sewage treatment processes, but the gas is usually wasted rather than trapped for recycling.
11 e. Extreme Methanogens methanogens produce methane (CH4) metabolism created most the natural gas (fossil fuel) reserves that are tapped as energy sources for domestic or industrial usecan be exploited to produce energy from waste materials
12 f. Extreme Halophiles locations Salt loving Dead Sea Great Salt Lake Evaporating PondsSalt lovingHalobacterium halobiumPurple membranebacteriorhodopsinheterotrophsImage source:Extreme halophiles live in natural environments such as the Dead Sea, the Great Salt Lake, or evaporating ponds of seawater where the salt concentration is very high (as high as 5 molar or 25 percent NaCl).These prokaryotes require salt for growth and will not grow at low salt concentrations. Their cell walls, ribosomes, and enzymes are stabilized by Na+. Halobacterium halobium, the prevalent species in the Great Salt Lake, adapts to the high-salt environment by the development of "purple membrane", actually patches of light-harvesting pigment in the plasma membrane. The pigment is a type of rhodopsin called bacteriorhodopsin which reacts with light in a way that forms a proton gradient on the membrane allowing the synthesis of ATP. This is the only example in nature of non photosynthetic photophosphorylation. These organisms are heterotrophs that normally respire by aerobic means. The high concentration of NaCl in their environment limits the availability of O2 for respiration so they are able to supplement their ATP-producing capacity by converting light energy into ATP using bacteriorhodopsin.Halobacterium salinariumis an extreme halophile that grows at 4 to 5 M NaCl and does not grow below 3 M NaCl. This freeze etched preparation shows the surface structure of the cell membrane and reveals smooth patches of "purple membrane" (bacteriorhodopsin) embedded in the plasma membrane.
13 f. Extreme HalophilesHalobacterium halobium, prevalent in the Great Salt Lake, adapts to the high-salt environment by the development of "purple membrane",
14 pigment in the plasma membrane rhodopsin called bacteriorhodopsin reacts with light in a way that forms a proton gradient on the membrane allowing the synthesis of ATP.Absorb green light and reflect red and blueEvolutionary link to photosynthesis
16 E. Metabolism Syphilis Obligate aerobes Require oxygen Mycobacterium tubberculosistuberculosisObligate anaerobesKilled by oxygenTreponema pallidiumSyphilisClostridium botulinumBotulismBoth with or without oxygen (facultative)cellular respirationfermentationSyphilisBotulism
17 E. Metabolism Heterotrophs Parasites Use organic molecules as food sourceParasitesObtain nutrients from living organismsSaprophytesFeed on dead organismorganic wastesRecyclers or decomposers-contain cellulase enzymes
18 E. Metabolism Photosynthetic Autotrophs Use Sunlight to make food Live in Ponds, streams, moist areas of landCyanobacteriaBlue-green, red or yellowChains of independent cells
19 Eubacteria Chemosynthetic Autotrophs Make food from chemosynthesisSulfurNitrogenConvert unusable atmospheric nitrogen into nitrogen containing compounds plant can use.nitrogen fixation by bacteria such as RhizobiumConvert sulfur to sulfuric acidSulfur-oxidizers grow at low pH (less than pH 2) because they acidify their own environment by oxidizing S (sulfur) to H2SO4 (sulfuric acid).Why Yellowstone stinks!
20 F. Bacterial Structure Very small cell Lack membrane bound organelles RibosomesLack nuclear membraneDNA circularNucleoidBiochemical processes in cytoplasmPlasmids –loops of DNAImage Source:Note the nucleoid region (n) where DNA is located as well as the electron dense areas of the cytoplasm (dark areas) on these two cells of Neisseria gonorrhoeae.Bacteria lack a nuclear membrane and membrane-bound organelles. Biochemical processes that normally occur in a choloroplast or mitochondrion of eukaryotes will take place in the cytoplasm of prokaryotes. Bacterial DNA is circular and arrayed in a region of the cell known as the nucleoid. Scattered within bacterial cytoplasm are numerous small loops of DNA known as plasmids. Bacterial genes are organized in by gene systems known as operons.
21 Typical Bacteria CellImage Source: Biggs, Alton, Kathleen Gregg, Whitney Crispen Hagins, and Chris Kapicka. Biology: The Dynamics of Life. Columbus: Glencoe/McGraw Hill, 2002.Inside Story: A Typical Bacteria Cell P.503Bacteria live in hypotonic environment, higher concentration of water molecules outside the cell than inside which causes the water to continuously enter the bacteria cell. The cell wall protects the bacteria from bursting by osmotic pressure.Scientists use a bacterium’s need to maintain its cell wall to destroy bacteria that cause disease.
22 Electron Micrograph of E. Coli Image Source:Bacteria lack the membrane-bound nuclei of eukaryotes; their DNA forms a tangle known as a nucleoid, but there is no membrane around the nucleoid, and the DNA is not bound to proteins as it is in eukaryotes.Whereas eukaryote DNA is organized into linear pieces, the chromosomes, bacterial DNA forms loops.Bacteria contain plasmids, or small loops of DNA, that can be transmitted from one cell to another, either in the course of sex (yes, bacteria have sex) or by viruses. This ability to trade genes with all comers makes bacteria amazingly adaptible; beneficial genes, like those for antibiotic resistance, may be spread very rapidly through bacterial populations. It also makes bacteria favorites of molecular biologists and genetic engineers; new genes can be inserted into bacteria with ease.Bacteria do not contain membrane-bound organelles such as mitochondria or chloroplasts, as eukaryotes do. However, photosynthetic bacteria, such as cyanobacteria, may be filled with tightly packed folds of their outer membrane. The effect of these membranes is to increase the potential surface area on which photosynthesis can take place.
23 PlamidsImage Source:Plasmids, small DNA fragments, are known from almost all bacterial cells. Plasmids carry between 2 and 30 genes. Some seem to have the ability to move in and out of the bacterial chromosome.
25 1. Asexual BINARY FISSION Asexual Reproduction Copies chromosomeAttach to cell’s plasma membraneDOUBLING THEIR NUMBERS EVERY 20 MINUTES**favored for genetic engineering**Image Source: Pearson Education Inc as Benjamin Cummings Publishers1. MOST BACTERIA reproduce by a process called BINARY FISSION.2. BINARY FISSION IS A PROCESS IN WHICH THE CHROMOSOMES REPLICATE, AFTER WHICH THE CELL DIVIDES.3. BINARY FISSION IS A TYPE OF ASEXUAL REPRODUCTION.4. Under ideal conditions, bacteria divide (reproduce) rapidly, DOUBLING THEIR NUMBERS EVERY 20 MINUTES.5. ALL BACTERIA ARE HAPLOID AND CONTAIN ABOUT 1/1000 AS MUCH DNA AS ORDINARY EUKARYOTIC CELLS. MOST BACTERIA'S DNA IS A SINGLE DOUBLE STRAND THAT ATTACHES TO THE CELL MEMBRANE AND REPLICATES JUST BEFORE THE CELL DIVIDESTheir small size, ability to rapidly reproduce (E. coli can reproduce by binary fission every 15 minutes), and diverse habitats/modes of existence make monerans the most abundant and diversified kingdom on Earth. Bacteria occur in almost every environment on Earth, from the bottom of the ocean floor, deep inside solid rock, to the cooling jackets of nuclear reactors.
26 2. Sexual Reproduction CONJUGATION Bacterium transfers all or part of its chromosomePilusImage Source: A. CONJUGATION - THE PROCESS OF EXCHANGING GENETIC MATERIAL THROUGH CELL-TO-CELL CONTACT (Conjugation bridge). During conjugation, DNA Moves from one bacteria cell to another, this allows the DNA to change and provide VARIATIONS and DIVERSITY of the generations of bacteria to follow. It Increases the chances that some bacteria will survive the environment changes. The bacteria attached together using special hairlike structures called PILI, a bridge of cytoplasm (CONJUGATION BRIDGE) forms between two bacteria cells, and the DNA passes from one cell to another.Bacterial ConjugationWatch the animation on the left side of the screen to see how bacteria share genes that encode resistance to antibiotics. This demonstration has been adapted from an animation developed by HHMI international research scholar B. Brett Finlay, Ph.D., for the 1999 Holiday Lectures on Science, 2000 and Beyond: Confronting the Microbe Menace.Part 1: The bacterial genomeThe animation begins with two bacteria meeting. Each one contains its own chromosome. Above the chromosome of one bacterium (bacterium A) is a plasmid, a portion of the bacterial genome that is separate from the chromosome. The plasmid of bacterium A is also known as Resistance (R) factor. It contains genes that encode different traits and can, as you will see, be transferred from one bacterium to another, and even between different species! In the case of this animation, the R factor encodes a molecule that provides resistance to the antibacterial drug X.Part 2: The bacterial sex pilusBacteria transfer genetic material through the sex pilus. The bacterium that contains the R factor creates the pilus, a tube that extends from the surface of the bacterial cell wall and connects bacterium A to bacterium B.Part 3: The transfer of the bacterial DNAThe two DNA strands of the R factor are separated and one of them moves across the sex pilus. As the plasmid enters bacterium B, complementary DNA synthesis occurs in both bacteria to generate double-stranded DNA. At the end of the process, a portion of bacterium A's genome has been duplicated in bacterium B.Part 4: Bacterium obtains multidrug resistanceOnce the R factor has been incorporated into the genome of bacterium B, the bacterium expresses a molecule on its surface that provides resistance to drug X.Bacterial Conjugation BackgroundMost bacteria contain a single chromosome that carries the cell's genetic information. In addition, bacteria often contain small circular, double-stranded DNA molecules called plasmids. Plasmids are not connected to the main bacterial chromosomes and replicate independently. Plasmids usually contain genes, such as those coding for antibiotic resistance and the production of toxins, that are not crucial to the survival of the bacterium under normal environmental conditions.Plasmids can be passed on from one bacterium to the other in a process called conjugation. Conjugation is one of the mechanisms by which bacteria can acquire new genetic material and, as a result, new traits.Bacterial Conjugation Animation Teaching TipsThe animations in this section have a wide variety of classroom applications. Use the tips below to get started but look for more specific teaching tips in the near future. Please tell us how you are using the animations in your classroom by sending toBacterial Conjugation CreditsDirector: Dennis Liu, Ph.D.Scientific Direction: B. Brett Finlay, Ph.D.Scientific Content: Laura Bonetta, Ph.D.Animators: Eric Keller, Satoshi Amagai, Ph.D.
27 1928 Fleming discovers penicillin the first antibiotic. Inhibits cell wall growth!3Image Source:1.Andrew McClenaghan/Science Source/Photo Researchers, Inc.2.Alexander Fleming's photo of the dish with bacteria and Penicillin mold3.In 1928, he was straightening up a pile of Petri dishes where he had been growing bacteria, but which had been piled in the sink. He opened each one and examined it before tossing it into the cleaning solution. One made him stop and say, "That's funny." Some mold was growing on one of the dishes... not too unusual, but all around the mold, the staph bacteria had been killed... very unusual. He took a sample of the mold. He found that it was from the penicillium family, later specified as Penicillium notatum. Fleming presented his findings in 1929, but they raised little interest. He published a report on penicillin and its potential uses in the British Journal of Experimental Pathology.Penicillin is effective against a wide range of disease-causing bacteria.Penicillin acts by killing bacteria directly or by inhibiting their cell wall growth.