Lecture 03_Micro I - Bacteriology PDF

Basic Bacteriology I BPM3: Lecture 3 Dr. Maria Ramos-Nino [email protected] 1 Eukaryotes are organisms whose cells have a nucleus enclosed within a nuclear envelope. Prokaryotes are single-celled organism which has neither a distinct nucleus with a membra...

Basic Bacteriology I BPM3: Lecture 3 Dr. Maria Ramos-Nino [email protected] 1 Eukaryotes are organisms whose cells have a nucleus enclosed within a nuclear envelope. Prokaryotes are single-celled organism which has neither a distinct nucleus with a membrane nor other specialized organelles https://sciencetrek.org/sciencetrek/topics/kingdoms/links.cfm 7 SOM.MKII.BPM3.7.1.1.M.MB.1 Bacterial Structure  Microbiology is the study of all living organisms that are too small to be visible with the naked eye 0.2-2uM Eye Bacteriology is the study of bacteria https://letstalkscience.ca/educational-resources/backgrounders/introduction-bacteria SOM.MKII.BPM3.7.1.1.M.MB.1 Bacterial Structure 8  Scope of microbiology CELLULAR ACELLULAR PROKARYOTES EUKARYOTES Viruses Bacteria Fungi Viroids (nucleic acid) Archaea Algae https://www.thoughtco.com/bacteria-shapes-373278 Prions (proteins) Protozoa https://news.uga.edu/new-model- predicts-which-animal-viruses-may- SOM.MKII.BPM3.7.1.1.M.MB.1 Bacterial Structure Helminths https://biologywise.com/protozoa-classification-characteristics spread-among-humans/ 9 Prokaryotes vs. Eukaryotes Eukaryotes 80s Ribosome (60s and 40s subunits) Multiple chromosomes Linear genome Membrane-bound organelles Ex. Nucleus, ER, etc. Prokaryotes 70s Ribosome (50s and 30s subunits) Single circular genome Plasmids* No membrane-bound organelles * Antimicrobial Resistance genes (AMR) 10 SOM.MKII.BPM3.7.1.1.M.MB.1 Bacterial Structure Murray, Medical Microbiology 7th edition Prokaryotes Cell morphology helps classify bacteria Pleomorphic Gram staining pattern is also used for classification: Gram-Positive Gram-Negative Atypicals 11 SOM.MKII.BPM3.7.1.1.M.MB.1 Bacterial Structure Gram Stain Method Bacteria are classified by shape and color, using Gram stain procedure discovered in 1882 by Hans Christian Gram  Heat fix bacteria on a glass slide  Stain bacteria with crystal violet (purple)  Apply iodine as a mordant to the crystal violet  De-stain bacteria with alcohol  Counter-stain with Pink Safranin https://meromicrobiology.blogspot.com/2011/08/gram-staining_03.html Gram Positive (+) = purple Gram Negative (-) = pink 13 SOM.MKI.BPM3.9.1.3.M.MB.3 Gram Stain  Gram Stain & Peptidoglycan https://www.onlinebiologynotes.com/difference-between-gram-positive-and-gram-negative-bacteria/ 14 SOM.MKI.BPM3.9.1.3.M.MB.3 Gram Stain  *Peptidoglycan layer retains the crystal violet of the Gram stain https://www.chegg.com/flashcards/lecture-2-57b9aae7-208b-4b68-a81b-a4238202d13d/deck 15 SOM.MKI.BPM3.9.1.3.M.MB.3 Gram Stain Bacterial Cell Structure Gram Positive Features Thick peptidoglycan layer Teichoic acid LipoTeichoic acid Gram Negative Features Thin peptidoglycan layer Outer Membrane Porins Lipopolysaccharide Lippincott Illustrated Reviews 16 SOM.MKI.BPM3.9.1.3.M.MB.3 Gram Stain Gram-negative cell wall: LPS Lipopolysaccharide- LPS Part of Outer membrane Only on Gram-negative bacteria LPS has 3 units: – “O” antigen Polysaccharide Somatic antigen for species https://www.researchgate.net/publication/293637294_Porphyromonas_gingivalis_An_Overv identification iew_of_Periodontopathic_Pathogen_Below_the_Gum_Line/figures?lo=1 – Ex. Serotype E.coli 0157:H7 – Core polysaccharide – Lipid A – toxic effect LPS functions as an endotoxin which triggers inflammation leading to sepsis 17 SOM.MKII.BPM3.8.1.2.M.MB.5 Gram negative bacteria Cell Wall - Peptidoglycan The peptidoglycan monomer is composed of 2 covalently bonded sugars with amino acids: NAM = n-acetylmuramic acid NAG = n-acetylglucosamine Pentapeptide chain (5 amino acids) Peptidoglycan layer is composed of repeating subunits of NAG & NAM, crosslinked by the sugars and trans-peptide bridges SOM.MKII.BPM3.7.1.1.M.MB.2 Bacterial replication 18 https://bio.libretexts.org, Chapter 2.3 The Peptidoglycan Cell Wall  Cell wall targeting  Transpeptidases or Penicillin-Binding Proteins PBPs catalyze the incorporation of the monomer into the adding it to the existing peptidoglycan wall matrix  PBPs are major drug target for β-lactam drugs, including penicillin PBP2….PBP2a=MRSA https://www.researchgate.net/publication/315900937_Penicillin%27s_Discovery_and_Antibiotic_Resista nce_Lessons_for_the_Future/figures?lo=1 19 SOM.MKII.BPM3.7.1.1.M.MB.2 Bacterial replication  Microbial Metabolism Metabolism: Powerhouse of organisms 21 SOM.MKII.BPM3.7.1.1.M.MB.6 Bacterial Metabolism Human Pathogens 22 SOM.MKII.BPM3.7.1.1.M.MB.6 Bacterial Metabolism 36 ATP-Eukaryotes Variable 2 ATP 38 ATP-Prokaryotes 23 SOM.MKII.BPM3.7.1.1.M.MB.6 Bacterial Metabolism Example: Use of microbial metabolism Industrial use Laboratory use 24 SOM.MKII.BPM3.7.1.1.M.MB.6 Bacterial Metabolism  Gram-Positive Bacteria Bacilli Cocci Branching Aerobic Anaerobic Aerobic Anaerobic Clostridium Actinomyces Listeria Bacillus Catalase - Catalase + Streptococcus Staphylococcus Corynebacterium S. pneumoniae  Gram-Negative Bacteria Diplococci Coccobacilli Bacilli Comma-shaped Oxidase + Aerobic Hemophilus Bartonella 42oC Alkaline Urease + Pasteurella media Neisseria Francisella Campylobacter Vibrio Helicobacter Moraxella Lactose - Lactose + Escherichia coli Oxidase - Oxidase + Klebsiella Enterobacter Shigella Pseudomonas Salmonella 27 SOM.MKII.BPM3.8.1.2.M.MB.5 Gram negative bacteria