Micro Lecture 3 2023 Bacteria and Archaea PDF

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AppropriateJasmine5753

Uploaded by AppropriateJasmine5753

London South Bank University

2023

Dr. Claire Atkinson

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bacteria archaea microbiology biological science

Summary

This micro lecture covers the structures, growth, and genetics of bacteria and archaea. It includes information on bacterial shapes, arrangements, and the process of binary fission. The lecture also discusses archaea, their differences from bacteria, and the role of acquired plasmids in disease.

Full Transcript

Lecture 3 Bacteria and Archaea Dr. Claire Atkinson Learning objectives By the end of the lecture you should be able to answer the following questions What are the varying structures (shapes and arrangements) of bacteria? How do bacteria g...

Lecture 3 Bacteria and Archaea Dr. Claire Atkinson Learning objectives By the end of the lecture you should be able to answer the following questions What are the varying structures (shapes and arrangements) of bacteria? How do bacteria grow? What are the genetics of bacteria? What are Archaea? How do Archaea differ from bacteria? Bacterial Cell Morphology Slonczewski J.L,.Microbiology: An Evolving Science. 5th Edition Mosby items and derived items © 2010 by Mosby, Inc., an affiliate of Elsevier Inc. Shapes Cocci Overall shape is spherical or nearly spherical Bacilli Rod-shaped Some endospore forming Pleomorphic e.g., Coccobacilli—bacilli that are elongated and spherical Mosby items and derived items © 2010 by Mosby, Inc., an affiliate of Elsevier Inc. Shapes Spirals Vibrio Vibrios Curved or comma-shaped rods Spirillum Thick, rigid, spiral organisms Spirochetes Thin, flexible spirals Mosby items and derived items © 2010 by Mosby, Inc., an affiliate of Elsevier Inc. Cocci Diplococci Two paired cocci e.g., Streptococcus pneumoniae Streptococci Beadlike chains e.g., Streptococcus pyogenes Tetrads Produced by division within two planes—cocci arranged in squares of four Sarcina Cocci arranged in cubes of eight as a result of division in three planes Staphylococci Grapelike clusters formed by cell division in random planes Mosby items and derived items © 2010 by Mosby, Inc., an affiliate of Elsevier Inc. Arrangements In addition to their shape, bacteria can also be categorized according to their arrangement and their style of grouping after cell division Arrangements of Cocci Staphylococcus Streptococcus Tetrads Mosby items and derived items © 2010 by Mosby, Inc., an affiliate of Elsevier Inc. Bacilli Diplobacilli Paired rods that remain in pairs after division Streptobacilli Fail to separate after they divide and remain in chains Identifying bacteria What is the Gram (positive or negative) of the cells? What is the cell shape of the cells How many species can you see in this Gram stain? Identifying bacteria Gram-negative (pink) Bacilli One species of bacteria??? – they are all pink rods Most common are Enterobacteriacae E. coli, Klebsiella, Salmonella Identifying bacteria What is the Gram (positive or negative) of the cells? What is the cell shape of the cells How many species can you see in this Gram stain? Identifying bacteria Gram positive (purple) Cocci in clusters One species - ? Staphylococcus – confirm with additional testing Identifying bacteria What is the Gram (positive or negative) of the cells? What is the cell shape of the cells How many species can you see in this Gram stain? Identifying bacteria Two different species of bacteria (Look for different cell shapes and different Gram results). One species is Gram-positive (purple) and one species is Gram-negative (pink). The Gram-positive cells are cocci and the Gram-negative cells are bacilli. Cell division Binary Fission Results in two Equal/Unequal daughter cells Sufficient metabolites necessary to divide A cascade of regulatory events must occur to initiate replication Once replication is started, DNA synthesis must run to completion When metabolites are depleted— cessation Equal / Unequal Mosby items and derived items © 2010 by Mosby, Inc., an affiliate of Elsevier Inc. Structure and Replication of Bacterial Cells Measuring Growth Dry weight (Measurement of cell mass) More accurate estimation More time-consuming Cells need to be washed and then dried Turbidity (cloudiness) Measured with spectrophotometer In optical density units The greater the cell mass—the less light will pass through Direct cell count Microscopically in counting chambers (Petroff-Hauser chambers) —slide with a grid of 25 small squares (known volume) Viable counts Only viable cells are counted Pour plating Spread plating Most probable quantitative method Brock Biology of Microorganisms, Global Editiony Michael T. Madigan; Kelly S. Bender; Daniel H. Buckley; W. Matthew Sattley; David A. Stahl 2018 Population Growth Curve Lag phase Bacteria have to adapt to medium before cell division Cells are metabolically active Logarithmic or exponential growth phase The rate of growth increases with time Each cell introduced to medium divides by binary fission Each subsequent binary fission doubles the bacterial cells Stationary phase Occurs when essential nutrients are depleted or byproducts of metabolism accumulate Death phase Begins when growth stops and the number of dead cells is larger than the number of viable cells Sloncewski J.L,.Microbiology: An Evolving Science. 5th Edition Mosby items and derived items © 2010 by Mosby, Inc., an affiliate of Elsevier Inc. Spores A spore is a dormant cell produced by certain microorganisms to survive adverse conditions: like high temperatures, radiation, desiccation, and chemical agents. Spore forming bacterium Favourable Unfavoura Conditions ble Conditions Microbiology: a Laboratory Manual, Global Edition James G. Cappuccino and Chad T. Welsh 2017 Questions Time for a break? Bacterial Genetics Genetics 46 Chromosomes Genome 21K genes The sum of genetic material in an organism In form of chromosome Chromosome Single DNA molecule Includes proteins (histones) in eukaryotes Prokaryotes do not have proteins associated with their DNA (nucleoid area) Gene Unit that codes for particular Information on a DNA molecule Brock Biology of Microorganisms, Global Editiony Michael T. Madigan; Kelly S. Bender; Daniel H. Buckley; W. Matthew Sattley; David A. Stahl 2018 Plasmid Genetics Episome Independent from chromosomal DNA A unit of genetic material Generally circular Composed of a series of genes Self-replicating Ori Can integrate itself into the chromosomal DNA of Between 5 and 100 genes the organism and therefore can stay intact and is Not essential for normal bacterial growth duplicated with every cell division Bacteria can gain or loose plasmids It becomes part of the genetic makeup Antibiotic resistance **The key difference between plasmid and episome is that plasmids are unable to integrate with bacterial chromosomal DNA Mosby items and derived items © 2010 by Mosby, Inc., an affiliate of while episomes are capable of integrating Elsevier Inc. with chromosomal DNA.** Genetic Transfer in Prokaryotes Transformation Transfer of free DNA from one cell to another Occurs naturally in many bacterial species Transduction Transfer of bacterial DNA from a bacteriophage into another cell 27 Brock Biology of Microorganisms, Global Editiony Michael T. Madigan; Kelly S. Bender; Daniel H. Buckley; W. Matthew Sattley; David A. Stahl 2022 Genetic Transfer in Prokaryotes Conjugation Transfer of genetic material during cell-to-cell contact Between mating cells of the same species or between closely related species Brock Biology of Microorganisms, Global Editiony Michael T. Madigan; Kelly S. Bender; Daniel H. Buckley; W. Matthew Sattley; David A. Stahl 2022 Genetic Transfer in Prokaryotes Conjugation Transfer of genetic material during cell-to-cell contact Between mating cells of the same species or between closely related species Brock Biology of Microorganisms, Global Editiony Michael T. Madigan; Kelly S. Bender; Daniel H. Buckley; W. Matthew Sattley; David A. Stahl 2022 Conjugation and antibiotic resistance ps://www.youtube.com/watch?v=dRY7DlTmtnw&t=23s Bacterial Conjugation - YouTube Disease connection: Black Death Figure 22.21 The Black Death. The (a) Great Plague of London killed an estimated 200,000 people, or about 20 percent of the city’s population. The causative agent, the (b) bacterium Yersinia pestis, is a Gram-negative, rod-shaped bacterium from the class Gammaproteobacteria. The disease is transmitted through the bite of an infected flea, which is carried on a rodent. Symptoms include swollen lymph nodes, fever, seizure, vomiting of blood, and (c) gangrene. (credit b: Rocky Mountain Laboratories, NIAID, NIH; scale-bar data from Matt Russell; credit c: Textbook of Military Medicine, Washington, D.C., U.S. Dept. of the Army, Office of the Surgeon General, Borden Institute) Disease connection: Black Death https://www.youtube.com/watch?v=pRZYb2Jl22g Evolutionary acquired plasmids Gut based bacteria Acquired genetic elements from the gut by horizontal gene transfer Distinguished by mobile genetic elements as Y. pseudotuberculosis and Y. pestis 98% similar on nucleotide level Questions What are Archea? Some of the oldest living organisms Classed as prokaryotes Often described as Extremophiles (live in very extreme environments) Single-celled Not much is known about them Due to inability to grow many in lab Not linked to any human LaXchange What are Archaea? Now know to be distributed in many environments, alongside bacteria including soil and water Many uses in industry Many enzymes produced from archaea Also produce biomethane, bioethanol LaXchange Bacteria and Archaea Differences LaXchange Bacteria and Archaea Differences Differences and Similarities between Bacteria and Archaea Structural Bacteria Archaea Characteristic Cell type Prokaryotic Prokaryotic Cell morphology Variable Variable Does not contain Cell wall Contains peptidoglycan peptidoglycan Lipid bilayer or lipid Cell membrane type Lipid bilayer monolayer Plasma membrane lipids Fatty acids-glycerol ester Phytanyl-glycerol ethers Chromosome Typically circular Typically circular Replication origins Single Multiple RNA polymerase Single Multiple Initiator tRNA Formyl-methionine Methionine Streptomycin inhibition Sensitive Resistant LaXchange Questions Don’t forget Classification Identification How do we distinguish if they are different microorganism? Phenotypic: how they look like: size, shape, organization, color, cell wall, metabolism, where are they found growing conditions, source of energy and C, and by products Analytic (their composition) Analyze all their components Genotypic (their genetic information-rRNA or all their DNA) Leboffe, M.J & Pierce, B.E. (2015) Microbiology: Laboratory Theory and Application Taxonomy Much more is known about bacteria than archaea Archaea are prokaryotes that are very similar to bacteria, but there are less studied as they tend to live in extreme conditions. They do not have peptidoglycan on their cell wall. Can be classified as: Methanogens: methane producers Thermophiles: heat lovers Halophiles: Salt lovers The formal system of organizing, classifying, and naming living organisms Domain(3) /Kingdom (6) Phylum (division for bacteria) Class Order Family Genus Species Strain VanMeter, K.C, VanMetter W.G and Hubert RJ. Microbiology for the healthcare professional. Elsevier. QUIZ time Question 1: Name the cell morphology a) b) Question 2: Name the arrangment a) b) Question 3: Bacterial cell division is mainly by? A. Budding B. Symmetrical division C. Fission D. Asymmetrical division Question 4: Some bacteria produce spores when? A. When conditions are favourable B. When conditions are unfavourable C. When they have optimal media D. Part of normal binary fission Question 5: During the exponential growth phse? A. Cells divide B. Cells don’t divide C. Turbidity remains the same D. Cells die Question 6: To live a chemohetrotroph needs? A. Only organic compounds B. Organic compounds and sunlight C. Organic compounds and CO2 Question 8: A plasmid is? A. Essential for bacterial growth B. Part of the chromosome C. >10,000 genes long D. Self replicating

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