Presentation on theme: "Introduction to Fermentation"— Presentation transcript:
1 Introduction to Fermentation Aspergillus niger and Lactobacillus
2 Introduction to Fermentation Aspergillus niger and Lactobacillus Delbruckii are the microbes used to commercially produce citric acid and lactic acid, respectively. The production takes place in a batch fermenter. This tutorial will introduce you to the following areas regarding batch fermentationMicrobial Growth KineticsMedia for Industrial FermentationsSterilizationThe Development of Inocula for Industrial FermentationsDesign of a FermenterInstrumentation and ControlAeration and Agitation
3 Microbial Growth Kinetics Microbial Growth Kinetics describe how the microbe grows in the fermenter. This information is important to determine optimal batch times. The growth of microbes in a fermenter can be broken down into four stages:Lag PhaseExponential PhaseStationary PhaseDeath Phase(Growth curve is from Shuler p. 161)
4 Microbial Growth Kinetics Lag PhaseThis is the first phase in the fermentation processThe cells have just been injected into a new environment and they need time to adjust accordinglyCell growth is minimal in this phase.
5 Microbial Growth Kinetics Exponential PhaseThe second phase in the fermentation processThe cells have adjusted to their environment and rapid growth takes placeCell growth rate is highest in this phase
6 Microbial Growth Kinetics Exponential Phase (Continued)At some point the cell growth rate will level off and become constantThe most likely cause of this leveling off is substrate limited inhibitionSubstrate limited inhibition means that the microbes do not have enough nutrients in the medium to continue multiplying.
7 Microbial Growth Kinetics Stationary phaseThis is the third phase in the fermentation processThe cell growth rate has leveled off and become constantThe number of cells multiplying equals the number of cells dying
8 Microbial Growth Kinetics Death phaseThe fourth phase in the fermentation processThe number of cells dying is greater than the number of cells multiplyingThe cause of the death phase is usually that the cells have consumed most of the nutrients in the medium and there is not enough left for sustainability
9 Media for Industrial Fermentations The media is the feed solutionIt must contain the essential nutrients needed for the microbe to growFactors of consideration when choosing media-Quality consistence and availability-Ensure there are no problems with Media Prep or other aspects of production processEx. Cane molasses, beet molasses, cereal grains
10 SterilizationSterilizing the feed solution is essential because the media cannot contain foreign microbes because this could severely hinder the growth of the production microbeMost popular method is heat sterilization of the feed solution
11 The Development of Inocula for Industrial Fermentations The inoculum is the starter culture that is injected into the fermenterIt must be of sufficient size for optimal growth kineticsSince the production fermenter in industrial fermentations is so large, the inoculum volume has to be quite large- A seed fermenter is usually required to produce the inoculum volume-The seed fermenter’s purpose is not to produce product but to prepare inoculum
12 Design of a Fermenter Factors to consider when designing a fermenter Aseptic and regulatory capability, long-term reliabilityAdequate aeration and agitationLow power consumptionTemperature and pH controlsSampling facilities(14 L fermenter shown is a copyright of New Brunswick Scientific)
13 Instrumentation and Control The success of a fermentation process is highly dependent on environmental factorsThe fermenter needs to be able to control such factors as temperature, pH, and dissolved oxygen levels
14 Aeration and Agitation Most industrial fermentations are aerobic processes meaning that the production microbe requires oxygen to growThe oxygen demand is met by sparging air through the fermentation vessel and using an agitator increase the amount of dissolved oxygen
15 ReferencesStanbury, P.F., A. Whitaker, and S. J. Hall, Principles of Fermentation Technology, 2nd ed., Butterworth Heinemann, Oxford, 2000.Shuler, M. L. and F. Kargi. Bioprocess Engineering Basic Concepts, 2nd ed., Prentice Hall, Upper Saddle River, NJ, 2002.