Industrial Microbiology

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Industrial Microbiology
2011-12-09 00:20:10
PMB 112 midterm3

general microbiology midterm 3
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  1. Why are few bacteria edible as cells?
    their small cells contain a relatively high amount of DNA and RNA which contains purines which are hard for humans to metabolize
  2. What role do lactobacillus play in the formation of cottage cheese?
    they ferment sugar to lactic acid, increasing the acidity and denaturing proteins that coagulate
  3. chocolate fermentation
    • yeast, lactic acid bacteria and acetic acid bacteria invovled
    • must happen immediately
    • use indigenous molecules
    • can not be stored or exported
  4. microbial products
    • cells
    • product from bioconversion of substrate and cells
    • products from cells
  5. industrial microbiology
    use of microorganisms, usually grown on a large scale, to produce valuable commercial products or carry out important chemical transformations

    • enhancement of exisiting microbial processes/reactions
    • production of new microbial products via gene manipulation (microbial biotechnology)
  6. biocatalysis
    reactions carried out by microorganisms in industrial microbiology
  7. *properties of a useful microorganism
    • yield:
    • produce substance of interest
    • capable of growth and product formation in large-scale culture
    • substance of interest is easily obtained from culture
    • amendable to genetic manipulation and genetically stable
    • easy to inoculate into large fermentors

    • safety:
    • not pathogenic

    • cost:
    • grow rapidly and produce product in short time period
    • grow in relatively inexpensive liquid culture medium (byproduct from another process)
    • can sell off byproduct from process
    • cost of purification

    bottom line: cost
  8. *primary metabolite
    • formed during growth phase
    • production is coupled with growth
    • ex. alcohol
  9. *secondary metabolite
    • formed near end of growth phase/stationary phase
    • not essential for growth and reproduction
    • production is highly dependent on growth conditions
    • often produced as group of closely-related structures
    • can often achieve dramatic overproduction of secondary metabolites
    • ex. penicillin
  10. considerations when optimizing production of microbial product
    • growth phase
    • primary vs. secondary metabolism
    • limitations on product formation
    • regulation of gene expression, protein expression, protein activity important
    • introducing novel genes
    • understand regulation
  11. *limitations on product formation
    • substrate availability
    • global repression
    • feedback inhibition
    • product stability
    • conversion of product to other compounds
  12. *introducing novel genes
    • codon usage
    • copy number
    • mini operon - expression is co-regulated
    • stabilize and destabilize transcript
  13. understanding regulation
    • allosteric effectors
    • catabolite repression
    • rate limiting step vs. shared control
  14. fermentors
    • vessel used for aerobic or anaerobic processes
    • scale up is critical and complicated
  15. immobilization of enzyme can facilitate biocatalysis
    • can facilitate enzymatic reaction in large scale continuous systems
    • stabilize enzymes - limit denaturation
    • immobilization via: bonding, cross-linking, enzyme inclusion