bacterial growth

Examples of bacterial growth in the following topics:

• Generation Time

  • Bacterial growth occurs by the division of one bacterium into two daughter cells in a process called binary fission.
  • Bacterial growth is the division of one bacterium into two daughter cells in a process called binary fission.
  • If the number surviving exceeds unity on average, the bacterial population undergoes exponential growth.
  • During this phase of the bacterial growth cycle, synthesis of RNA, enzymes, and other molecules occurs.
  • This basic batch culture growth model draws out and emphasizes aspects of bacterial growth which may differ from the growth of macrofauna.

• Growth Rate and Temperature

  • Bacterial growth is the division of one bacterium into two daughter cells in a process called binary fission.
  • Hence, local doubling of the bacterial population occurs.
  • However, if the number surviving exceeds unity on average, the bacterial population undergoes exponential growth .
  • The measurement of an exponential bacterial growth curve in batch culture was traditionally a part of the training of all microbiologists.
  • Describe how the growth of bacteria is affected by temperature and how bacterial growth can be measured

• Enrichment and Isolation

  • Growth in closed culture systems, such as a batch culture in LB broth, where no additional nutrients are added and waste products are not removed, the bacterial growth will follow a predicted growth curve and can be modeled .
  • During the lag phase of the bacterial growth cycle, synthesis of RNA, enzymes and other molecules occurs.
  • Batch culture is the most common laboratory-growth method in which bacterial growth is studied, but it is only one of many.
  • This is a chemostat, also known as an open or continuous culture: a steady state defined by the rates of nutrient supply and bacterial growth.
  • Bacterial growth can be suppressed with bacteriostats, without necessarily killing the bacteria.

• Production of Vaccines, Antibiotics, and Hormones

  • Antibiotics are biotechnological products that inhibit bacterial growth or kill bacteria.
  • They are naturally produced by microorganisms, such as fungi, to attain an advantage over bacterial populations.
  • In this classification, antibiotics are divided into two broad groups according to their biological effect on microorganisms: bactericidal agents kill bacteria, and bacteriostatic agents slow down or stall bacterial growth .
  • In recent times, human growth hormone (HGH) has been used to treat growth disorders in children.
  • Assays such as the one shown help scientists understand the effects of antibiotics on bacterial species.

• Units of Measurement for Microbes

  • Microbial growth is an important measure in understanding microbes.
  • The measurement of an exponential microbial growth curve in batch culture was traditionally a part of the training of all microbiologists; The basic means requires bacterial enumeration (cell counting) by direct and individual (microscopic, flow cytometry), direct and bulk (biomass), indirect and individual (colony counting), or indirect and bulk (most probable number, turbidity, nutrient uptake) methods .
  • Since there are limits on space, food, and other factors, actual growth never matches actual measured growth.
  • This chart shows the logarithmic growth of bacteria.
  • The phases of growth are labelled on top.

• Antibiotic Classifications

  • Bactericidal antibiotics kill bacteria; bacteriostatic antibiotics slow their growth or reproduction.
  • Bactericidal antibiotics kill bacteria; bacteriostatic antibiotics inhibit their growth or reproduction.
  • Other ways that bactericidal antibiotics kill bacteria include inhibiting bacterial enzymes or protein translation.
  • Bacteriostatic antibiotics limit the growth of bacteria by interfering with bacterial protein production, DNA replication, or other aspects of bacterial cellular metabolism.
  • The MIC (minimum inhibitory concentration) is the minimum concentration of drug which can inhibit the growth of the microorganism.

• Unclassified and Uncultured Bacteria

  • Classification seeks to describe the diversity of bacterial species by naming and grouping organisms based on similarities.
  • Culture techniques are designed to promote the growth and identify particular bacteria, while restricting the growth of the other bacteria in the sample.
  • Once a pathogenic organism has been isolated, it can be further characterized by its morphology, by growth patterns such as aerobic or anaerobic growth, by patterns of hemolysis and by staining.
  • However, recent advances in molecular techniques do allow the sequencing of DNA from bacterial species, without the reliance on a pure culture of that given bacteria.
  • However, even using these improved methods, the total number of bacterial species is not known and cannot even be estimated with any certainty.

• Preserving Bacterial Cultures

  • Whenever you successfully transform a bacterial culture with a plasmid or whenever you obtain a new bacterial strain, you will want to make a long term stock of that bacteria.
  • While it is possible to make a long term stock from cells in the stationary phase, ideally your culture should be in logarithmic growth phase.
  • An erlenmeyer containing a bacterial culture.
  • Describe how bacterial cultures can be stored for a long time at -80C in glycerol

• Damage to the Cell Wall

  • The cell wall is responsible for bacterial cell survival and protection against environmental factors and antimicrobial stress.
  • The cell wall of gram-negative bacteria is thin (approximately only 10 nanometers in thickness), and is typically comprised of only two to five layers of peptidoglycan, depending on the growth stage.
  • An example of an antibiotic that interferes with bacterial cell wall synthesis is Penicillin.
  • A bacterial cell with a damaged cell wall cannot undergo binary fission and is thus certain to die .
  • Discuss the effects that damage to the cell wall has on the bacterial cell

• Direct Counting

  • Direct counting methods are used to determine bacterial concentration without the need for advanced equipment.
  • One can also quantify the number of cells in a culture by plating a known volume of the cell culture on a petri dish with a growth medium, which is also known as a streak plate.
  • Bacterial colony counts made from plating dilutions of bacteria are useful to estimate the strength of bacterial infections; for example, a urinary tract bacterial infection.