CHAP5:MICROBIAL GROWTH

• Inoculation


  -introduction of microbes into culture medium
• Culture


  -microbes that growing in culture medium
• colony


  -visible growth of the microbes in the culture media
• culture media


  -mimic the culture of a microbes
• culture


  -called to microbes that grow in culture media
• Carbon source of microbes for culture medium

  1. heterotroph- plants and animals extracts
  2. autotroph- extract from carbon dioxide which produce organic substance material
• culture medium


  -a nutrient material prepared for the growth of microbes in lab
• turbidity


  -cloudy sign of growth of a microbes in culture media
• modern media


  -are purchased in a dried form
• broth


  -media can be use in liquid form
• types of media

  • liquid form- generally stored in test tube
  • solid form- usually used agar which is a polysaccharide that derived from seaweed
• spectrophotometer


  -an apparatus that are essential in microbial growth

  -an instrument that measures the amount of photons (the intensity of light) absorbed after it passes through sample solution.
• once solidified,agar does not melt until it reach 100 degree celsius of boiling.this remains solid in all normal incubation temperature
• once,melted,agar remains liquid until the temperature reaches about about 40 degree celsius
• slant


  -if the agar in test tube is solidified while the test tube are tilted
• agar deep


  -if the test tube is left vertical while the agar sets
• plate


  -a petri dish containing agar
• Bacterial culture media can be classified into three;

  • based on consistency
  • based on nutritional component
  • based on its functional use
• classification on consistency;


  culture media can be liquid,semi-solid,or solid
• Liquid media


  -these are available for use in test tubes,bottles or flask.

  -can sometimes refer as broth
• surface pellicle


  certaon aerobic bacteria and those containing fumbriae are known to grown as a thin film{e.g,vibrio and bacillus}
• solid media


  -any liquid medium can be rendered by the addition of certain solidifying agents
• agar


  -is the most commonly used as solidifying agent
• semi-solid agar


  -reducing the amount of agar to 0.2-0.5% renders as a medium semi solid
• agar in consistency


  liquid media-0 agar

  solid media-1.5% agar

  semi solid agar-2.5% agar and microphilic bacteria
• classification based on nutritional component


  media are classified as simple,complex,and synthetic or defined
• simple medium


  -such as peptone water,nutrient agar can support most non-fastidious bacteria
• complex{undefined}medium


  -is one in which the exact chemical constitution of the medium is not known or have ingredients whose components are difficult to estimate
• synthetic or chemically defines medium


  -is one in which the exact chemical composition which is known and specially prepared for research purposes
• classification based on functional us or application


  these include the basal media,enriched media,selective/enrichment media and differential media
• basal media


  -are basically simple media that support most non-fastidious bacteria
• enriched medium


  -is broth or solid medium containing a rich supply of special nutrient for the growth of a particular discrimination organism,but not for other microorganisms that might be present
• selective media


  -has added inhibitors to discourage the growth of a certain organism but not inhibit the one sought
• bismuth sulfite agar


  -is used to isolate the typhoid bacterium in gram negative like salmonella typhi
• mannitol salt agar


  -is selective for staphylococci because most other bacteria cannot grow in its high salt environment
• brilliant green agar


  -a medium that inhibits gram positive bacteria while permitting gram negative organism such as salmonella species to grow
• enrichment medium


  similar to selective media but designed to increase the numbers of desired microbes to detectable levels
• differential medium


  -is used to grow several species of bacteria but each will have a distinctive appearance
• eosine methylene blue agar{EMB}


  -frequently used to separate and identify gram negative organism in fecal specimens
• microbial growth


  -refers to the growth of a population or an increase in the number of cells,and not to an increase in the size of the individual cells