fermentation2004

8/7/2019 Fermentation2004

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Introduction toIntroduction to

FermentationFermentationAspergillus nigerAspergillus niger andand LactobacillusLactobacillus


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Introduction to FermentationIntroduction to Fermentation

Aspergillus nigerAspergillus niger andand Lactobacillus DelbruckiiLactobacillus Delbruckii are theare themicrobes used to commercially produce citric acid andmicrobes used to commercially produce citric acid andlactic acid, respectively. The production takes place in alactic acid, respectively. The production takes place in abatch fermenter. This tutorial will introduce you to thebatch fermenter. This tutorial will introduce you to the

following areas regarding batch fermentationfollowing areas regarding batch fermentation Microbial Growth KineticsMicrobial Growth Kinetics

Media for Industrial FermentationsMedia for Industrial Fermentations

SterilizationSterilization

The Development of Inocula for Industrial FermentationsThe Development of Inocula for Industrial Fermentations

Design of a FermenterDesign of a Fermenter Instrumentation and ControlInstrumentation and Control

Aeration and AgitationAeration and Agitation


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Microbial Growth KineticsMicrobial Growth Kinetics

Microbial Growth KineticsMicrobial Growth Kineticsdescribe how the microbedescribe how the microbegrows in the fermenter. Thisgrows in the fermenter. Thisinformation is important toinformation is important todetermine optimal batch times.determine optimal batch times.

The growth of microbes in aThe growth of microbes in afermenter can be broken downfermenter can be broken downinto four stages:into four stages: Lag PhaseLag Phase

Exponential PhaseExponential Phase

Stationary PhaseStationary Phase

Death PhaseDeath Phase

(Growth curve is from Shuler p.(Growth curve is from Shuler p.161)161)


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Lag PhaseLag Phase This is the first phase in the fermentationThis is the first phase in the fermentation

processprocess

The cells have just been injected into a newThe cells have just been injected into a newenvironment and they need time to adjustenvironment and they need time to adjustaccordinglyaccordingly

Cell growth is minimal in this phase.Cell growth is minimal in this phase.


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Exponential PhaseExponential Phase The second phase in the fermentation processThe second phase in the fermentation process

The cells have adjusted to their environmentThe cells have adjusted to their environmentand rapid growth takes placeand rapid growth takes place

Cell growth rate is highest in this phaseCell growth rate is highest in this phase


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Exponential Phase (Continued)Exponential Phase (Continued) At some point the cell growth rate will levelAt some point the cell growth rate will level

off and become constantoff and become constant

The most likely cause of this leveling off isThe most likely cause of this leveling off issubstrate limited inhibitionsubstrate limited inhibition

Substrate limited inhibition means that theSubstrate limited inhibition means that the

microbes do not have enough nutrients in themicrobes do not have enough nutrients in themedium to continue multiplying.medium to continue multiplying.


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Stationary phaseStationary phase This is the third phase in the fermentationThis is the third phase in the fermentation

processprocess

The cell growth rate has leveled off andThe cell growth rate has leveled off andbecome constantbecome constant

The number of cells multiplying equals theThe number of cells multiplying equals the

number of cells dyingnumber of cells dying


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Death phaseDeath phase The fourth phase in the fermentation processThe fourth phase in the fermentation process

The number of cells dying is greater than theThe number of cells dying is greater than thenumber of cells multiplyingnumber of cells multiplying

The cause of the death phase is usually that theThe cause of the death phase is usually that thecells have consumed most of the nutrients in thecells have consumed most of the nutrients in themedium and there is not enough left formedium and there is not enough left forsustainabilitysustainability


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Media for Industrial FermentationsMedia for Industrial Fermentations

The media is the feed solutionThe media is the feed solution It must contain the essential nutrients needed for theIt must contain the essential nutrients needed for the

microbe to growmicrobe to grow

Factors of consideration when choosing mediaFactors of consideration when choosing media--Quality consistence and availabilityQuality consistence and availability

--Ensure there are no problems with Media Prep orEnsure there are no problems with Media Prep orother aspects of production processother aspects of production process

Ex. Cane molasses, beet molasses, cereal grainsEx. Cane molasses, beet molasses, cereal grains


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SterilizationSterilization

Sterilizing the feed solution is essentialSterilizing the feed solution is essentialbecause the media cannot contain foreignbecause the media cannot contain foreign

microbes because this could severelymicrobes because this could severelyhinder the growth of the productionhinder the growth of the productionmicrobemicrobe

Most popular method is heat sterilization ofMost popular method is heat sterilization of

the feed solutionthe feed solution


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The Development of Inocula forThe Development of Inocula for

Industrial FermentationsIndustrial Fermentations The inoculum is the starter culture that isThe inoculum is the starter culture that isinjected into the fermenterinjected into the fermenter It must be of sufficient size for optimal growthIt must be of sufficient size for optimal growth

kineticskinetics Since the production fermenter in industrialSince the production fermenter in industrial

fermentations is so large, the inoculum volumefermentations is so large, the inoculum volumehas to be quite largehas to be quite large

-- A seed fermenter is usually required to produce theA seed fermenter is usually required to produce theinoculum volumeinoculum volume

--The seed fermenters purpose is not to produceThe seed fermenters purpose is not to produceproduct but to prepare inoculumproduct but to prepare inoculum


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Design of a FermenterDesign of a Fermenter

Factors to consider whenFactors to consider whendesigning a fermenterdesigning a fermenter Aseptic and regulatoryAseptic and regulatory

capability, longcapability, long--termtermreliabilityreliability

Adequate aeration andAdequate aeration andagitationagitation

Low power consumptionLow power consumption Temperature and pHTemperature and pH

controlscontrols Sampling facilitiesSampling facilities

(14 L fermenter shown is a(14 L fermenter shown is acopyright of Newcopyright of NewBrunswickScientific)BrunswickScientific)


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Instrumentation and ControlInstrumentation and Control

The success of a fermentation process isThe success of a fermentation process ishighly dependent on environmentalhighly dependent on environmentalfactorsfactors

The fermenter needs to be able to controlThe fermenter needs to be able to controlsuch factors as temperature, pH, andsuch factors as temperature, pH, anddissolved oxygen levelsdissolved oxygen levels


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Aeration and AgitationAeration and Agitation

Most industrial fermentations are aerobicMost industrial fermentations are aerobicprocesses meaning that the productionprocesses meaning that the productionmicrobe requires oxygen to growmicrobe requires oxygen to grow

The oxygen demand is met by sparging airThe oxygen demand is met by sparging airthrough the fermentation vessel and using anthrough the fermentation vessel and using anagitator increase the amount of dissolvedagitator increase the amount of dissolved

oxygenoxygen


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ReferencesReferences

Stanbury, P.F., A. Whitaker, and S. J. Hall,Stanbury, P.F., A. Whitaker, and S. J. Hall,Principles of Fermentation TechnologyPrinciples of Fermentation Technology, 2, 2ndnd

ed., Butterworth Heinemann, Oxford,ed., Butterworth Heinemann, Oxford,2000.2000.

Shuler, M. L. and F. Kargi.Shuler, M. L. and F. Kargi. BioprocessBioprocessEngineering Basic ConceptsEngineering Basic Concepts, 2, 2ndnd ed.,ed.,

Prentice Hall, Upper Saddle River, NJ,Prentice Hall, Upper Saddle River, NJ,2002.2002.

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