Microbial Physiology & Genetics (Two Lectures) By Prof. Dr. Zainalabideen A Abdulla, DTM&H., MRCPI, Ph.D., FRCPath. (U.K.) Second Lecture

Anabolism/Anabolic reactions - Require energy; bonds are formed - Energy provided by simultaneous catabolic reactions Example: 2 Monosaccharides Disaccharide Similarly for Proteins & Nucleic Acids Organic: Photosynthesis; Chemosynthesis

Photosynthesis - Light energy Chemical energy (bond) - Photoautotroph, e.g. Cyanobactia - Photoheterotroph, e.g. some bacteria -Trap light energy into chemical bonds in ATP, Glucose More ATP by aerobic respiration - Oxygenic photosynthetic bacteria (Produce O2) Anoxygenic PSB (no O2), e.g. Bacteria use S or H

Cont./…. Photosynthesis Q. Photosynthesis is the reverse of aerobic respiration; Why? CO2+ Water Glucose + Oxygen - If no light: Survive Anaerobically by fermentation OR: become Photoheterotrophic

Chemosynthesis - Chemoautotrophs: Chemotrophs use CO2 e.g., Primitive bacteria Archaea (methanogens) 4H2 + CO2 CH4 + 2H2O - Chemoheterotrophs: Organics (other than CO2) e.g., Most bacteria, Fungi, Protozoa, Animals, Humans

Bacterial Genetics Genetics: The study of heredity Genotype (genome): Complete collection of genes Phenotype: Physical traits, attributes, characteristics; Dictated by genotype (manifestations) e.g., Bacterial enzymes, capsule, flagella Chromosome: A circular strand of linked genes Genes: Direct all functions of cell, e.g. mRNA (product)

Mutation - DNA of gene altered Alter gene product & Trait Transmissible to offspring - Categories: 1. Beneficial, e.g. R to antibiotic 2. Harmful (sometimes Lethal) e.g. Non-functioning enzyme (Lethal) NOT always 3. Silent: Most bacterial mutations

Spontaneous mutations Random/Natural Some genes: More prone Rate: Per 10,000 – 1 Trillion DNA replication rounds (average 1 million) Increased: Physical or Chemical agents (Mutagens) Mutant (an organism with mutation), e.g. Sabin live vaccine is a mutant strain- for poliomyelitis Ames Test (1960): Mutagen may be also carcinogen (cause cancer)

Bacterial new genetic information 1. Lysogenic conversion 2. Transduction 3. Transformation 4. Conjugation

Plasmid Extra-chromosomal DNA in the cytoplasm Genes (many or few) on plasmid New genetic information acquired Replicate with or without chromosomal DNA (episome- autonomous or integrated plasmid)

Lysogenic Conversion Phages 1. Virulent (lytic) 2. Temperate (Not lytic; Lysogenic) Lysogeny: DNA injected into bacteria but no lysis Prophage: Remaining phage DNA in bacteria Lysogenic bacteria (Cell): Bacteria with prophage; Phage DNA replicate with bacteria daughter cell

cont./… Lysogenic conversion Phage conversion : A lysogenic bacterium is capable of producing one or more new gene products and exhibit new properties (i.e. converted). Examples of m.o. with prophage become pathogenic: C. diphtheriae: Diphtheria; tox gene S. pyogenes: Scarlet fever C. botulinum: Botulism V. cholera: Cholera

Transduction (“to carry across”) - Involves temperate bacteriophages - Prophage activated (stimulants) new viruses/ attached bacterial genes carried to other cells - Two types: General and Specialized

Transformation - Uptake/absorb of DNA (“naked DNA”) = Competence and “competent bacteria” - Examples: S. pneumoniae: DNA extract of Capsulated + non-capsulated broth Capsulated m.o*. Streptococcus + Staphylococcus Others: Bacillus, Haemophilus, Neisseria, Pseudomonas Latent virus gene (in human) + Bacteria (indigenous microbiota) Parkinson Dis. * Oswald Avery and Colleagues: Experiment

Conjugation ( see figures ) - Sex pilus (F pilus = conjugation bridge) - Donor (F+) attaches Recipient (F-) bacteria by F pilus - Pilus retracts Relaxase splits plasmid dsDNA - Is not reproduction (Bacterial mating/ male & female) Examples: Enteric bacilli, Pseudomonas - Transfer antibiotic resistance (R Factor= multiple drug resistance = “superbug”) and fertility factors (F+ and high frequency of recombination “Hfr+”)

Genetic engineering (≠ Recombinant DNA Technology) - Human genes Plasmid (Vector = Vehicle) Examples: E. coli, Yeast, Human macrophages and fibroblasts (manufacturing plants): GH (somatotropin) Somatostatin (Inhibitor) Insulin Interferon Agriculture (resistant plants) Marine bacterium to break oil down

Gene Therapy - Insertion of normal human gene into cells: Viral delivery (e.g. adenoviruses, retroviruses) Bacterial (Bacto-infection, e.g., Salmonella) Synthetic vector ( ? For the future) - Prescribe genes (drugs) to treat: Autoimmune diseases Sickle cell anaemia Immunodeficiency disorders Cancers Many other conditions