Minya University Faculty of Engineering Chemical Engineering Department Fundamentals of Biochemical Engineering “Types of Bacteria” By: Omar Ahmed Ali Supervision: Prof. Dr. Nagat Abdalla Mostafa 2024 Classification System • 3 Domains 1978 Carl Woese • 1. Bacteria • Unicellular prokaryotes with cell wall containing peptidoglycan • 2. Archaea • Unicellular prokaryotes with no peptodoglycan in cell wall • 3. Eukarya • Protista • Fungi • Plantae • Animalia Comparing Prokaryotic and Eukaryotic Cells Taxonomic Classification Categories • arranged in hierarchical order • species is basic unit Domain Kingdom Phylum or Division Class Order Family Genus Species Prokaryote Classification • Technologies used to characterize and ID prokaryotes • microscopic examination • culture characteristics • biochemical testing • nucleic acid analysis • combination of the above is most accurate Phenotypic & Genotypic classification Phenotypic Characteristics for Identifying Prokaryotes • often does not require sophisticated equipment • can easily be done anywhere Microscopic Phenotypic Exam size and shape and arrangement enough information for diagnosis of certain infections Gram stain distinguishes between Gram + and Gram – bacteria narrows the possibilities quickly Microscopic Phenotypic Exam • special stain • allows for the distinction of microorganisms with unique characteristics • capsule • acid fast staining detects the waxy presence of Mycobacterium tuberculosis Capsule staining Acid fast staining of M. tuberculosis CELL WALL Gram positive cell wall • Consists of • a thick, homogenous sheath of peptidoglycan 20-80 nm thick • tightly bound acidic polysaccharides, including teichoic acid and lipoteichoic acid • cell membrane • Retain crystal violet and stain purple Gram negative cell wall • Consists of • an outer membrane containing lipopolysaccharide (LPS) • thin shell of peptidoglycan • periplasmic space • inner membrane • Lose crystal violet and stain pink from safranin counterstain 10 Gram Positive Gram Negative 11 The Gram Stain Gram's iodine Crystal violet Decolorise with acetone Gram-positives appear purple Counterstain with e.g. methyl red Gram-negatives 12 appear pink Gram-positive cocci Gram-positive rods Gram-negative cocci Gram-negative rods 14 Metabolic Phenotypic Exam • cultural approaches • required for positive diagnosis of infection • isolation and ID of pathogen • accuracy, reliability, and speed • methods used include • culture characteristics • biochemical reactions process Serological Testing Phenotypic Exam • serological testing uses ELISA testing • fast and easy to use Classification of bacteria Classification of medically significant bacteria • I.Thick rigid walled cells A. Free living extracellular 1.Gram positive a.Cocci Staphylococcus - abcess Streptococcus - puemonia, Pharyngitis cellulitis b.Spore forming rods Aerobic Bacillus - Anthrax Anaerobic Clostridium - tetanus,gas gangrene botulism c.Non spore forming rods (GRAM POSTIVE CONTD) 1-Non filamentous Cornybacterium – Diphtheria Listeria - meningitis 2.Filamentous Actinomycetes – Actinomycosis Nocardia - Nocardiosis 2.Gram negative A.Cocci Neisseria -Gonorrhoea, meningitis B.Rods 1.Facultative a. Straight 1.Respiratory org. Haemophillus- meningitis Bordatella-Whooping cough Legionella- Pneumonia 2.Zoonotic Brucella – Brucallosis Francisella –Tularemia Pasteurella –Cellulitis Yersinia - Plague 3.enteric & related (GRAM NEGATIVE CONTD) E.coli - UTI,Diarrhoea Enterobacter – UTI Serratia – Pneumonia Klebsiella – Pneumonia.UTI Salmonella – enterocolitis,typhoid fever Shigella – Enterocolitis Proteus – UTI b. Curved Campylobacter – Entericolitis helicobacter – Gastritis,Peptic ulcer Vibrio - Cholera (Gram negative) C.Aerobic pneumonia,UTI D. Anaerobic Pseudomonas – Bacteroids – peritonitis 3.ACID FAST MYCOBACTERIUM - Tuberculosis & Leprosy B . Non free living obligate intracellular parasites 1.Rickettsia – Rocky mountain spotted fever Typhus, Q fever 2.Chlamydia urethritis, trachoma. Psittacosis Flexible thin walled Spirochaetes - Treponema – Syphilis Borrelia – Lyme disease Leptospira - leptospirosis Wall- less cells Mycoplasma - pneumonia Subtyping & Its applications To distinguishinguish between strains of different species Biotyping Serotyping Antimicrobial susceptibility system Bacteriophage typing Bacteriocin typing Genotypic Characteristics for Identifying Prokaryotes • the use of genotypic testing has increased with the availability of technology • genotypic testing is particularly useful in the case of organisms that are difficult to identify • several techniques include • gene probes • PCR • sequencing rRNA gene probes single stranded DNA that has been labeled with a identifiable tag, such as a fluorescent dye are complementary to target nucleotide sequences unique in DNA of pathogen Genotypic Characteristics used in Classifying Prokaryotes( non culture methods) • PCR: polymerase chain reaction • used to detect small amounts of DNA present in a sample (blood, food, soil) • the PCR chain reaction is used to amplify the amount of DNA present • sequencing ribosomal RNA of particular use for identifying prokaryotes impossible to grow in a culture focus is place on the 16S molecules of the RNA because of it’s size • approximately 1500 nucleotides once the 16S molecule is sequenced, it can then be compared to the sequences of known organisms Genotypic Characteristics used in Classifying Prokaryotes • comparison of nucleotide sequences • differences in DNA sequence can assist in determination of divergence of evolutionary path for organisms • DNA hybridization • single strands of DNA anneal • 16S ribonucleic acid • comparing sequence of ribosomal RNA • relatedness to other organisms can be determined using numerical taxonomy • determined by the percentage of characteristics two organisms have in common Thank You
