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MICRO 4130- EXAM 2 lecture 7/8
Terms in this set (65)
fermentation from latin, fevere=
metabolism in which organic molecules function as final electron acceptor
when final electron acceptor is inorganic eg O2
in industrial microbiology, fermentation is simple a large scale _____, even when the condition is aerobic
any process for the production of a product by means of mass culture of micro- organisms
what are the three fermentation operation modes?
batch, fed batch, continuous
closed system, fix volume, culture goes through lag, exponential, stationary, and death phases- not regulated, down time between batches, specific growth rate, maximum growth rate
is batch fermentation for the production of primary or secondary metabolites?
can use for secondary by keeping it at stationary phase or for primary by using exponential phase
what does the picture represent?
partially closed system, new media added at interval with or without removal of culture, balanced growth rate and concentration of growth limiting compounds- regulated, allow higher accumulation of cells/products
fed batch fermentation
is fed batch fermentation used for primary or secondary metabolite production?
secondary- ex: antibiotics
open system, fresh sterile medium is constantly added and same amount of medium containing microorganisms and products is constantly taken out, culture maintained at a highly productive state, difficult to avoid contamination, no down time, pre determined growth rate
continuous fermentation (chemostat)
phase where product is harvested and the fermenter must be cleaned before restarting the cycle
continuous fermentation is used for the production of __________ metabolites
the dilution rate at which the complete wash out of cells is avoided in continuous fermentation
critical dilution rate
at what point is D>Umax (maximum specific growth rate)?
when curve is going down
examples of continuous fermentation
waste treatment, fermentation to make ethanol , cell propagation
waste stream keeps flowing in; convert dissolved materials and particulate matter too fine for collection to microbial cells that can be removed
biological waste treatment
microbial cells are often the starting material for isolation of their _________
continuous bioreactors can have cells growing rapidly with a high proportion of cells that are relatively physiologically young for higher ______ production
fermentors are also known as?
fermentor, a vessel or arrangement for creating conditions for optimum production in fermentations through:
elimination/reduction of contaminations; provision of optimum aeration, acidity, pH, temperature, nutrient availability, and other environmental conditions
fermentation process in which microorganisms grow on solid materials without the presence of free liquid- solid substrates
fermentation using liquid substrates
rotating drum fermentors, tray fermentors, bed systems, column bioreactors, fluidized bed reactors
stirred tank reactor, bubble column, air lift, packed bed
what is the most common solid state fermentor and have been used for centuries in Asia for fermented foods
advantages of solid state fermentor
low cost, simplicity
disadvantages of solid state fermentor
difficulty of controlling temp, pH, water, etc.
what are the parameters controlled within the aerated stirred tank batch fermentor?
construction, aeration, sterility, temp control, foam control, inoculum preparation
most modern fermentors are?
the aerated stirred tank batch fermentor should be welded, avoiding ________ which can shield old media from sterilization and lead to microbial contamination
modern fermentors are __________
Oxygen critical for aerobic organisms, contributes about _____ to fermentation costs
______ (stirrer, impellers, and baffles) reduce bubble size
oxygen is essential for _______ and _______ of metabolites in aerobic organisms
what must occur for oxygen to be absorbed by microorganisms?
it must be dissolved in aqueous solution along with the nutrients
air ordinarily contain only 20% of ________ but _________ is also highly insoluble in water
water holds less O2 at ________ temperatures; at 20 degree C, water holds only about 9 ppm of oxygen
for some highly aerobic fermentation such as the growth of yeast or production of citric acid, oxygen is so critical that even if _____________ it would contain only a 15 second supply for the organisms
the broth were entirely saturated with oxygen
air used in most fermentation is ______
the air in a fermentor is forced under pressure at the bottom through a?
the ______ the holes the finer the bubbles and the more effective the supply of oxygen to the microbes in a fermentor
what is the problem with too small holes in a fermentor?
will require more pressure and increase consumption of energy and costs
since the size of the fermentor holes are fixed (.25-3 cm in diameter) the amount of ______ fed into the medium can be controlled by altering the pressure of the incoming air
the fermentor and growth medium are sterilized with _____, sometimes separately
the influent and exhaust air are ______
available in fermentors when temps need to be raised
circulated in jacket to cool fermentation
water (sometimes refrigerated)
are dispersions of gas in liquids
foams result from _______ and ________ in fermentation
fermentors are only _____% full, to allow for foaming
why are foams a problem in fermentations?
may restrict aeration/agitation- affecting growth; introduce contaminations
______ from organisms stabilize foams, ______ are major foam stabilizers
foams constant through fermentation, not common:
foam half life rises then drops:
microorganisms utilize foam stabilizers
foam half life drops, then rises: microorganisms utilize foam stabilizers and later _____
produce some themselves
initially medium has low foam stabilizers; stabilizers increase with _______; foam half life may drop again if some components metabolized
what are the two methods that control foams?
mechanically breaking up with fan, anti foam chemicals let in as foam touches probe
natural oils, peanut oil, soybean oil; alcohols, synthetic chemicals: polyethers, silicones
what has to be true of carefully selected anti foams?
need to be on GRAS- non toxic, no adverse odors, autoclavable, low cost
the source of the organism to inoculate a fermentor is often a ______ containing the lyophilized organism
if the contents of the vial were introduced directly into the fermentor...
it would take very long to attain the active population and contaminants likely to outgrow the organisms
incoculum is usually ____ of the production volume
beginning from laboratory shaken conical flasks through _______ fermentors thro ______ fermentors to the ________ fermentor
small, pilot, production
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