Batch fermentation is a closed culture on an industrial scale. The fermenter is filled with a fixed amount of sterile nutrient medium, inoculated with the microorganism, and sealed. Nothing more is added (apart from air, or acid or alkali for pH control) and nothing is removed until the end.The microorganisms go through the lag, log and stationary phases, just like a lab closed culture. At the end of a set time the fermenter is emptied, the product is separated and purified, and the vessel is cleaned and sterilised for the next batch.Batch fermentation is used to make secondary metabolites. These are substances that are not essential for growth and are made mainly in the stationary phase, when nutrients are running low. Penicillin, made by Penicillium, is the classic example. (Primary metabolites, needed for growth, are made during the log phase.)Advantages
• Easy to set up and control.
• If contamination occurs, only one batch is lost.
• Well suited to secondary metabolites, because the culture naturally reaches the stationary phase.
• The same fermenter can be used for different products.Disadvantages
• Growth is slower overall, because much of the time is spent in the lag phase and in cleaning and refilling (down time).
• Productivity per unit of fermenter volume is lower than in continuous fermentation.
• Conditions change during the run as nutrients are used and waste builds up.
• Easy to set up and control.
• If contamination occurs, only one batch is lost.
• Well suited to secondary metabolites, because the culture naturally reaches the stationary phase.
• The same fermenter can be used for different products.Disadvantages
• Growth is slower overall, because much of the time is spent in the lag phase and in cleaning and refilling (down time).
• Productivity per unit of fermenter volume is lower than in continuous fermentation.
• Conditions change during the run as nutrients are used and waste builds up.