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Microbiology Growth, Culture, and Antimicrobial Control

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Terms in this set (31)

  • Psychrophiles
    Microbes that grow at temperatures below 15°C with an optimum near 0°C; found in deep oceans and polar regions.
  • Mesophiles
    Microbes with optimum growth between 20°C and 40°C; commonly found in animal microbiota and pathogens.
  • Cardinal temperatures
    The minimum, optimum, and maximum temperatures at which a microbial species can grow.
  • pH preference of most bacteria
    Most bacteria grow best at near-neutral pH, typically around pH 7.
  • Obligate halophiles
    Microbes that require high salt concentrations for growth.
  • Chemoheterotrophs vs Autotrophs (carbon source)
    Chemoheterotrophs use organic compounds for carbon, whereas autotrophs use carbon dioxide.
  • Oxygen requirement: Obligate aerobes
    Require oxygen for growth and perform aerobic respiration only.
  • Oxygen requirement: Facultative anaerobes
    Can grow with or without oxygen; use fermentation or anaerobic respiration when oxygen is absent.
  • Toxic oxygen forms
    Reactive oxygen species including singlet oxygen, superoxide radical, peroxide, and hydroxyl radical that can damage cells.
  • Catalase test purpose
    Detects presence of catalase enzyme by breaking down hydrogen peroxide into water and oxygen.
  • Culture medium
    A nutrient preparation used to support microbial growth.
  • Selective media
    Contain inhibitors to suppress unwanted microbes and favor growth of desired organisms.
  • Differential media
    Distinguish organisms by visible differences in growth or biochemical reactions.
  • Reducing media
    Support growth of anaerobes by chemically removing oxygen.
  • Biosafety Level 3 (BSL-3)
    Containment level for highly infectious airborne pathogens; includes biosafety cabinets and negative pressure rooms.
  • Pure culture
    A culture containing only one species or strain of microorganism.
  • Binary fission
    A bacterial cell division process involving elongation, DNA replication, septum formation, and separation into two cells.
  • Sterilization
    The process that removes or destroys all microbial life, including endospores.
  • Autoclave standard conditions
    Sterilization at 15 psi pressure and 121°C temperature for 15 minutes.
  • Pasteurization
    Heat treatment that reduces pathogens and spoilage organisms without complete sterilization.
  • Filtration for sterilization
    Removes microbes from heat-sensitive fluids and air using membrane or HEPA filters.
  • Disk-diffusion method
    A test where antibiotic-soaked disks are placed on inoculated agar to evaluate antimicrobial effectiveness by zones of inhibition.
  • Phenol and phenolics
    Chemical agents that injure plasma membrane lipids and remain active in the presence of organic matter.
  • Selective toxicity
    The property of a drug to harm microbes more than host cells.
  • Bactericidal vs Bacteriostatic
    Bactericidal agents kill microbes; bacteriostatic agents inhibit microbial growth without killing.
  • Penicillin mechanism of action
    Blocks peptidoglycan cross-linking, disrupting bacterial cell wall synthesis.
  • Aminoglycosides target
    Bind to the 30S ribosomal subunit, causing misreading of mRNA and inhibiting protein synthesis.
  • Quinolones mechanism
    Inhibit DNA gyrase or topoisomerases, blocking nucleic acid synthesis.
  • Sulfonamides mode of action
    Compete with PABA to inhibit folic acid synthesis, an essential metabolite.
  • Antifungal drug target
    Many antifungals disrupt ergosterol synthesis or function, increasing membrane permeability.
  • Superinfection
    Overgrowth of resistant normal microbiota during antimicrobial treatment, e.g., Candida albicans or Clostridioides difficile.