3 What is fermentation?Pasteur’s definition: “life without air”, anaeroberedox reactions in organisms.New definition: a form of metabolism in which the end products could be further oxidized.For example: a yeast cell obtains 2 molecules ofATP per molecule of glucose when it ferments itto ethanol.
4 What is fermentation?Microorganisms, typically grown on a large scale, to produce valuable commercial products or to carry out important chemical transformations. This process is commonly referred to as Fermentation.
5 Types of fermentation process There are two methods of fermentation used to produce enzymes.submerged fermentationsolid-state fermentation.
6 Submerged fermentation/ Solid-state fermentation Submerged fermentation involves the production of enzymes by microorganisms (e.g. bacteria, yeast) in a liquid nutrient media (water content of the media: > 95%)Solid-state fermentation is the cultivation of microorganisms on a solid substrate.Carbon containing compounds in or on the substrate are broken down by the micro organisms, which produce the enzymes either intra-cellularly or extra-cellularly.
7 Submerged fermentation/ Solid-state fermentation Cont…. The enzymes are recovered by methods such as centrifugation, for extra cellularly produced enzymesand lysing of cells for intracellular enzymes.Many industries are dependent on enzymes for the production of their goods.Industries that use enzymes generated by fermentation are the brewing, wine making, baking and cheese making.
8 Submerged Fermentation Cont… Advantages:Measure of process parameters is easier than with solid-state fermentation.Bacterial and yeast cells are evenly distributed throughout the medium.There is a high water content which is ideal for bacteria.Disadvantages:High costs due to the expensive media.
9 2. Solid State Fermentation Solid-state fermentation (SSF) is another method used for the production of enzymes.In solid state, water content is 40~ 80%.Solid-state fermentation involves the cultivation of microorganisms on a solid substrate, such as rice husk, wheat bran, sugar beet pulp, wheat and corn flour.
10 Solid State Fermentation Cont… Advantages:SSF has many advantages over submerged fermentation. These include:High volumetric productivityRelatively high concentration of productLess effluent generatedSimple fermentation equipment.
12 Aerobic fermentation Adequate aeration. Bioreactors- adequate supply of sterile air.In addition, these fermentors may have a mechanism for stirring and mixing of the medium and cells .eg. Antibiotics, enzymes, vitamins.
13 Anaerobic fermentation In anaerobic fermentation, a provision for aeration is usually not needed.e.g. Lactic acid, ethanol, wineWhen referring to fermentation regarding food, there are no distinctions betweenanaerobic and aerobic metabolism.
14 Cont….Fermentation changes the characteristics of the food by the action of the enzymes produced by bacteria, mould and yeasts, which can occur in aerobic or anaerobic conditions
15 Cont….The process of fermentation requires a food source (e.g. glucose); enzymes formbacteria or yeast and (depending on the product) anaerobic or aerobic conditions.
16 Cont..Of all the microbial products manufactured commercially, antibiotics are the most important.Antibiotics are chemical substances produced by microorganisms to kill other microorganisms.They are used in the treatment of infectious diseases.
17 RANGES OF FERMENTATION PROCESS Microbial cell (Biomass)….YeastMicrobial enzymes….Glucose isomeraseMicrobial metabolites….PenicillinFood products….Cheese, yoghurt, vinegarVitamins….B12, riboflavinTransformation reactions….Steroid biotransformation
26 Fermentation could be: Batch modeFed batch mode (continuous)
27 Batch fermentation Most fermentations are batch processes Nutrients and the inoculum are added to the sterile fermentor and left to get on with it!Anti-foaming agent may be added.Once the desired amount of product is present in the fermentor the contents are drained off and the product is extracted.After emptying, the tank is cleaned & prepared for a new batch.
28 Continuous fermentation Some products are made by a continuous culture system.Sterile medium is added to the fermentation with a balancing withdrawal of broth for product extraction.
29 Fermentation MediumDefinition of medium nutritional, hormonal, and substrate requirement of cellsIn most cases, the medium is independent of the bioreactor design and process parametersType of medium: complex and synthetic medium (mineral medium)Even small modifications in the medium could change cell line stability, product quality, yield, operational parameters, and downstream processing.
30 Medium Composition Fermentation medium consists of: Macronutrients : (C, H, N, S, P, Mg sources water, sugars, lipid, amino acids, salt minerals)Micronutrients: (trace elements/ metals, vitamins)Additional factors: growth factors, attachment proteins, transport proteins, etc)For aerobic culture, oxygen is sparged
31 InoculumsIncoculum is the substance/ cell culture that is introduced to the medium. The cell then grow in the medium, conducting metabolisms.Inoculum is prepared for the inoculation before the fermentation starts.It needs to be optimized for better performance:Adaptation in the mediumMutation (DNA recombinant, radiation, chemical addition)
32 Required value generation in fermentors as a function of size and productivity
33 Microbial rates of consumption or production C, N, P, S sourceH2OH+biomassCO2O2productheat