Bacterial growth

• Define Macronutrients

  
  

  Required by bacteria in large amounts, present in all cells
• Define Micronutrients

  
  

  Required by bacteria in small amounts, not required by all organisms
• What are the main uses of macroelements in bacteria

  Proteins, Carbohydrates, Lipids and nucleic acids.
• What is the role of microelements in bacteria

  Components of enzymes
• What are Chemically defined media

  The exact chemical composition is known
• Complex media

  Exact chemical composition not known, made of digests of complex material
• List the aseptic techniques for culturing bacteria

  • FLaming the loop to sterilise it
  • Flame the tube tip
• Define microbiological growth

  An increase in cell numbers
• Bacterial multiplication

  Binary fission to produce a new generation of 2 cells.
• Bacterial generation time[doubling time]

  Time needed for a population to double
• What are the features of bacterial growth

  Exponential under ideal conditions. This means it has a constant doubling time.
• What is batch culture

  The culture is grown in a closed system meaning that no additional nutrients are added and no waste iis isremoved.
• What substances is bacteria cultured on

  Solid and liquid
• Types of antimicrobial agents on growth

  1. Bacteriostatic

  2. Bacteriocidal

  3. Bacteriolytic
• What is culture media

  Nutrient solutions that provide all the elements required for growth
• What type of media is Nutrient agar plates

  Solid
• Label the bacteria growth graph and describe it

  Lag phase: Cells are adjusting to the new environment.

  Exponential growth: Growth rate is at its max.

  Stationary phase: Reproduction is no longer happening as conditions become less favourable.

  A) Lag phase

  B) Exponential growth

  C) Stationary phase

  D) Death phase

  
• What is the difference between culturable and viable cells?

  Culturable cells can be grown on a culture media.

  Viable cells are alive but are not dividing or cannot divide on the conventional media.
• What are the methods for counting bacteria micrscopically

  Total. Viable. Culturable.
• What is total count of bacteria

  All the viable and dead cells.
• How is total count done

  All bacteria are stained.
• What does a direct microscopic count determine

  Total cell count
• What is viable count

  Counts all the cells with metabolic activity.
• How is viable count done

  Using fluorescent activity dyes
• How is culturable count done

  Using a colony count
• How is a colony count done

  You incubate your sample and assume each colony comes from one culturable cell.
• Are non-culturable bacteria still pathogenic

  Yes
• What do bacteriostatic do

  Prevent replication
• What do bacteriocidal's do

  Kill the bacteria
• What do bacteriolytic's do

  Cause lysis of the bacteria
• What are obligate aerobes 


  Need oxygen for growth
• What are obligate anerobes

  Cannot grow in Oxygen
• What are facultative anaerobes

  Can grow with or without oxygen
• What are aerotolerant anerobes 


  Will tolerate Oxygen for growth
• What are microaerophilics

  Need oxygen for growth but can tolerate low oxygen concentrations
• What are psychrophiles

  Bacteria that grow best below 15 C. They are unable to grow above 20 C.
• What are mesophiles


  Bacteria which grow best between 20 and 40 C.
• What are thermophiles 


  Bacteria which grow best between 45 and 80 C.
• What are hyperthermophiles 


  Bacteria which grow best above 80 C.
• What type of bacteria are human pathogens

  Mesophiles.