Prokaryote biology, Gram staining, conjugation/transformation/transduction, biofilms, extremophiles.
Microbiology
Prokaryote
Domain of single-celled organisms lacking membrane-bound nucleus: Bacteria + Archaea. Circular genome in nucleoid; 70S ribosomes; diverse…
Gram staining
Differential staining distinguishing Gram-positive (thick peptidoglycan, purple) from Gram-negative (thin peptidoglycan + outer LPS…
Peptidoglycan
Bacterial cell-wall polymer of glycan strands (NAG-NAM) cross-linked by peptide stems. Target of β-lactam antibiotics (inhibit…
Bacterial conjugation
Plasmid transfer between bacteria via sex pilus (F-pilus encoded by tra operon). Major driver of horizontal gene transfer +…
Bacterial transformation
Uptake of free environmental DNA by competent bacteria. Griffith 1928, Avery-MacLeod-McCarty 1944 identified DNA as transforming principle…
Quorum sensing
Cell-density-dependent coordination via diffusible autoinducers (AHL in Gram-, AIP in Gram+, AI-2 universal). Regulates biofilm, virulence,…
Biofilm
Surface-attached microbial community embedded in self-produced extracellular polymeric substance (EPS: polysaccharides, proteins, eDNA).…
Extremophile
Organism thriving in physically/chemically extreme environment. Thermophiles (Thermus, Pyrococcus, >80°C), halophiles (Halobacterium, 5M…
Bacterial endospore
Dormant dehydrated structure in Bacillus, Clostridium. Extreme heat/chemical resistance; germinates on favourable conditions. Basis for…
Archaea
Third domain of life (Woese 1977). Distinctive lipid membranes (ether-linked isoprenoids), histones, eukaryote-like transcription.…
Monod bacterial growth kinetics
Monod 1942: μ(S) = μ_max S/(K_s+S) describes specific growth rate vs limiting substrate. Combined with chemostat dilution rate D defines…
Quorum sensing bistable autoinducer threshold
LuxR/AHL autoinducer accumulates with cell density; positive-feedback transcription of luxI yields bistability between low- and high-state.…
Germ theory (Pasteur-Koch)
Pasteur 1860s + Koch 1876 germ-theory; Koch's-postulates 1884 anthrax + tuberculosis; foundation of medical-microbiology.
Human microbiome (HMP 2007)
NIH Human-Microbiome-Project 2007 + 2012; modern American Gut + skin + oral; trillions of cells + 1000s of species.
Antibiotic resistance
Modern WHO 2019 AMR review; efflux + enzymatic-degradation + target-modification; modern phage-therapy + AMP + bacteriocin alternatives.
Biofilms (Costerton 1995)
J W Costerton 1995 biofilm-paradigm; modern indwelling-medical-device infections; quorum-sensing + ECM + persister-cells.
CRISPR-Cas immunity (Barrangou 2007)
Barrangou 2007 CRISPR-Cas bacterial adaptive-immunity; spurred CRISPR-genome-engineering; foundational microbiology + biotech.
Metagenomics (Handelsman 2004)
J Handelsman 2004 metagenomics; modern shotgun-metagenomics + Earth-Microbiome-Project + GTDB-classification.
Koch postulates (1876)
R Koch 1876 (Nobel 1905) postulates + Pasteur germ-theory; modern modern foundational + 2024 metagenomic-Koch postulates microbiome…
Luria-Delbrück (1943)
S Luria-M Delbrück 1943 (Nobel 1969) fluctuation-test mutation-rate; modern modern foundational text + 2024 ML-mutation-rate single-cell…
Three domains (Woese 1990)
C Woese 1977 + 1990 archaea/bacteria/eukarya; modern modern foundational text + 2024 Asgard-archaea + LUCA-genome reconstruction.
Phage therapy (d'Hérelle 1917)
F d'Hérelle-F Twort 1915-1917 bacteriophage; modern modern foundational text + 2024 phage-therapy clinical-trials antibiotic-resistance MDR.
CRISPR (Mojica 2005)
F Mojica 2005 + Barrangou-Horvath 2007 CRISPR-Cas adaptive-immunity bacterial; modern modern foundational + 2020 Doudna-Charpentier Nobel.
Biofilm (Costerton 1978)
J W Costerton 1978 biofilm-mode; modern modern foundational text + 2024 biofilm-AMR + quorum-sensing therapeutic-target chronic-infection.