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Ultrastructure and Morphological Classification of Bacteria.pdf
- 2. INTRODUCTION Bacteria are the smallest free living organisms (prokaryotes). They are the oldest fossils (3.5 billion y/o). They represent a large & diverse group of microorganisms existing as single cells/clusters of cells. Immense importance due to their rapid growth, reproduction, mutation rates & their ability to exist under adverse conditions. Can cause contamination, spoilage of many pharmaceutical products Bacteria 2
- 3. CLASSIFICATION Heterotrophs • Derive energy from breaking down complex organic compounds in the environment. • Saprobes- bacteria feeding on decaying material & organic wastes. • Parasites absorb nutrients from living organisms. Autotrophs • Photosynthetic- energy from sun • Chemosynthetic- breaking down inorganic substances for energy
- 4. DESCRIPTIVE TERMS Bacteria 4 Descriptive Term Adaptive Feature Psychrophile Growth range -40°C to 20°C Mesophile Growth range +20°C to +40°C Thermophile Growth range +40°C to +85°C Thermoduric Endure high temperatures Halophile Salt-tolerant Acidophile Acid-tolerant Aerobe Oxygen requiring Obligate anaerobe Oxygen poisoned Autotroph Uses inorganic material Heterotroph Needs organic material
- 5. EUBACTERIA • Prokaryotic microorganisms consisting of a single cell lacking a nucleus & containing DNA (single circular chromosome). • Can be Gram +/- • Economic, agricultural & medical importance • Examples: E.coli, Lactobacillus, Azospirillum Bacteria 5
- 6. CYANOBACTERIA • Group of bacteria (single cells/chains of cells) • Modern photosynthesis; Oxygen is derived from water • Plants inherited same ability Bacteria 6
- 7. ACTINOMYCETES • The Actinomycetes are a group of unicellular filamentous bacteria that form a branching network of filaments & produce spores. • Gram positive bacteria • Group of aerobic & anaerobic bacteria • They have long been recognized as sources of severe earthy-musty tastes & odors in drinking water • Produce antibiotics (streptomycin & novobiocin) • Actinomycetes form associations with some non-leguminous plants & fix N, which is then available to both the host & other plants in the near vicinity. Bacteria 7
- 8. BACTERIAL STRUCTURE Bacteria 8 Structure Description Function Flagella Long helical-shaped structures projecting from cell surface Protein flagellin Bacterial motility Flagellar motor rotates flagellum causing bacterium to move through the environment Pilli Longer than fimbriae Type of appendage Genetic exchange process of conjugation Capsules Tight fairly rigid layer closely associated with cell Protection against desiccation Protective barrier against penetration of biocides, disinfectants & +vely charged antibiotics Protection against engulfment by phagocytes & protozoa Act as a cement binding cells to each other & to substratum in biofilms
- 9. Bacteria 9 Structure Description Function Cell envelope All layers from cell membrane, cell wall, periplasmic space, outer membrane & capsule Cell membrane Fragile phospholipid bilayer with random protein distribution No sterols Transport of nutrients Energy generation Electron transport Location for regulatory proteins & biosynthetic proteins Cell wall Made up of peptidoglycan/ murein/ glycopeptide Large macromolecule containing glycan chains that are cross-linked by short peptide bonds Maintenance of shape & integrity of bacterial cell Strong rigid structural components to withstand osmotic pressures caused by high chemical [inorganic ions] in cell Cytoplasm Consists of approx. 80% water and 20% salts and proteins Contains enzymes to generate ATP from glucose oxidation Enzymes for peptidoglycan subunits synthesis
- 10. Bacteria 10 Structure Description Function Nucleoid Singular covalently closed circular molecule of double-stranded DNA 4600 kilobase pairs Complex with small amounts of proteins & RNA No histones Regulates growth Reproduction Regulates functions of bacteria Ribosomes 70s in size Made up of 2 subunits (30s & 50s) Peptidyl transferase Peptidyl synthesis Fimbriae Shorter than Pilli Type of appendage Act as adhesins allowing organisms to attach to surfaces Initiate biofilm formation Responsible for haemagglutination & cell clumping in bacteria Plasmids Small circular pieces of double- stranded extrachromosomal DNA Autonomous replication Encode for auxiliary functions May transfer antibiotic resistance readily from one organism to another & between species
- 11. Bacteria 11 Structure Description Function Mesosomes Small invagination in cell membrane DNA replication Cell division Excretion of exoenzymes Inclusion Bodies Consist of storage material composed of Carbon, nitrogen, sulphur or phosphate Act as repositories of these nutrients when shortages occur. Examples: poly-β-hydroxy- butyrate, glycogen and polyphosphate
- 12. Bacteria 12
- 13. SIMPLE DIFFUSION Movement of solute from an area of high concentration to an area of low concentration 13
- 14. FACILITATED DIFFUSION Movement of solutes from a high concentration to a low concentration through transport proteins 14
- 15. OSMOSIS Movement of water across a selectively permeable membrane from an area of high water concentration to a lower one Osmotic pressure is the pressure needed to stop the movement of water across the membrane Isotonic: no net movement of water Hypotonic: water moves into the cell causing it to burst (osmosis lysis ) Hypertonic: water moves out of the cell causing plasmolysis 15
- 16. ACTIVE TRANSPORT Movement of substances across membrane by the help of ATP and transporter protein. 16
- 18. TYPES OF CELL WALLS GRAM POSITIVE • Purple staining • Thick peptidoglycan • Staphylococci, all streptococci and some listeria species • No outer lipid membrane • No oxygen specific side chains • Teichoic and lipoteichoic acids present • Periplasmic space absent • Exotoxins produced • Highly susceptible to penicillin • 2 ringed flagellar structure GRAM NEGATIVE • Pink staining • Thin peptidoglycan • Enterobacter species, salmonella species, pseudomonas species • Outer lipid membrane present • Oxygen specific side chains present • Teichoic and lipoteichoic acids absent • Periplasmic space present • Endotoxins produced • Low susceptibility to penicillin • 4 ringed flagellar 18
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- 21. REFERENCES • Microbiology [Michael J. Pelczar, JR, E.C.S Chan, Noel R. Krieg] • Pharmaceutical Microbiology [ Hugo and Russell] • https://www.technologynetworks.com/immunology/articles/gram-positive-vs-gram-negative-323007 21