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Biotechnology > F. Biotech L3 > Flashcards

F. Biotech L3 Flashcards

1
Q

What does cell immobilization do

A

Changes cell biology

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2
Q

Methods of immobilizing cells

A
  • Containment of cells in membrane
  • Attach cells to solid substrate
  • Entrapment of cells in gel
  • Flocculation
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3
Q

Advantages of cell immobilization

A
  • High cell density
  • No wash out of cells ;easy to hold onto them)
  • Reduce contamination; high cell conc, no need to reuse
  • Reduce growth inhibition
  • Separate cells and medium
  • Increase product yield
  • Faster speed of fermentation
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4
Q

Disadvantage of cell immobilization

A
  • Difficult to maintain yeast viability; viability drops, cells die
  • Stability over time (system breaks down)
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5
Q

Containment of cells in membrane bioreactors

A

Involves trapping of cells into a porous material eg dialysis tube. The medium goes in, ferments the product and is then released.

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6
Q

Problem with containment of cells

A

As cells replicate, membrane gets clogged

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7
Q

Attachment of cells to a solid substrate

A

Make use of gluteraldehyde to cross link. Yeast cells can then be added so they can attach to the surface

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8
Q

What is gluteraldehyde?

A

It is a preservative that makes surfaces sticky

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9
Q

Problem with attachment of cells to cell surface

A

Some cells are trapped and the rest bud off and float away

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10
Q

Entrapment or cells in alginate beads

A

Cells are trapped in sodium alginate, they are then added to CaCl2 solution and form beads.

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11
Q

Advantage of entrapping cells in beads

A

Beads are porous, stable, diffusable. They are used in a wide range of systems eg batch fermentation, cell recycle batch fermentation. The beads can be used free or packed in columns. As a result, there is increased ethanol production and faster fermentation.

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12
Q

Problem with entrapping cells in beads

A

Calcium chelating agents eg phosphate reacts with Ca and removes Ca from calcium alginate making it dissolve. Gas then builds up in the beads making it unstable

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13
Q

What other gels/ synthetic polymers can cells be trapped in?

A

Gel- Agar, gelatin
Synthetic polymer- Polyacrylamide

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14
Q

Flocculation

A

Cell walls become sticky, forming clumps of cells at a very high cell density. Some yeast cells flocculate naturally. Usually occurs in stationary phase but they can be tweaked to occur earlier

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15
Q

Downstream processing

A

Involves pulling out and concentrating products for the consumer. Difficult to do.

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16
Q

Product recovery of ethanol

A

A product with low level of ethanol is distilled and the ethanol is taken up and concentrated until you get a greater ethanol concentration (whiskey)

17
Q

Product recovery of proteins

A

Isolate and purify

18
Q

What is the main problem with downstream processing

A

Getting product out. If the product is in the cells, they have to be broken up to get the product out.

19
Q

Ways in which a cell can be disrupted

A
  • Sonification
  • Agitation
  • French press
  • Cell wall degradation
  • Controlled autolysis
20
Q

Sonication

A

Use of sound waves to break cells

21
Q

Agitation

A

Can be carried out with the use of glass beads to smash cells up

22
Q

Cell wall degradation makes use of?

A

Enzymes to chop cells up

23
Q

Isolation of intracellular enzymes can be carried out by:

A
  1. Removing nucleus acids from cell debris with the use of nuclease which chops up DNA
  2. Concentration of the product
    - for soluble proteins, ammonium sulphate ppt can be used for salting out proteins. This is used for precipitation of enzymes
    - for proteins present in membranes, PEG can be added to disrupt membranes to release things trapped inside.
    This is used for microsomal enzymes
24
Q

What does PEG stand for

A

Polyethyleneglycol

25
Q

Cell breakage can be?

A

Mechanical or non-mechanical

26
Q

Mechanical methods of cell breakage

A
  • Grinding
  • Pressure
  • Ultrasound
27
Q

Non-mechanical methods of cell breakage

A
  • Dessication
  • Lysis
28
Q

Means of separating cells

A
  • Size
  • Diffusivity
  • Ionic charge
  • Solubility
  • Density
29
Q

Separation based on size can be carried out by?

A
  • Ultracentrifugation
  • Gel chromatography
30
Q

Separation based on diffusivity can be carried out by?

A

Dialysis

31
Q

Separation based on ionic charge can be carried out by?

A

Electrolysis

32
Q

Separation based on solubility can be carried out by?

A

Solvent extraction

33
Q

Separation based on density can be carried out by?

A

Centrifugation

34
Q

Characteristics of downstream processing

A
  • Maximum recovery of products
  • Process must be reliable and continuous
  • Large reductions in volume
  • Final broth must be usable
  • Processing commence as broth leaves fermenter
  • Cost considerations

Biotechnology (3 decks)

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