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The components of a fermenter include the growth chamber, impellers, spargers, baffles, sensors, fluid pumps and computer system.

  • Growth chamber (Reservoir): The major function of a fermenter is to provide a controlled environment for the growth of microorganisms in order to obtain desired end-products that are of economic importance. The growth chamber or reservoir is the interior part of the fermentation vessel that has direct contact with fermentation medium and the organism. It is designed in such a way that minimizes microbial contamination of the process; and it ensures optimal sterilization of the vessel. The growth chamber of a fermenter defines the environments boundaries, integrates control of the growth parameters such as pH, and temperature, and it also prevents contamination. The growth chamber is constructed from various materials but the most used materials include metals, glass or plastics. However, a cylindrical non-corrosive stainless steel is often the most preferred since it meets most of the criteria for the interior of a fermenter – such as withstanding high temperature and being resistant to corrosion and contamination.
  • Impellers: Impellers are structures in fermentation vessels which are used to bring about agitation (i.e. appropriate stirring of the fermentation medium with other mixtures in the vessel). Impellers help to distribute incoming air as fine bubbles and it also help to mix the organisms in a uniform manner. Impellers create localized turbulence in the vessel and it also ensures uniform temperature distribution in the growth chamber. Agitation helps in gas dispersion and reduction of the thickness of the inoculum. The impellers are usually connected to a motor through the cover plate of the vessel, and it is the rotating action of the motor that drives the impellers into action via a rotary or linear motion.
  • Spargers: Spargers are devices used for forcible aeration in aerated stirred tank batch fermenters. They are the main means through which aeration is achieved in the fermentation vessel. Sterile filtered oxygen or air usually enters the fermentation vessel through sparger systems in such a manner that support the optimal growth of aerobic microorganisms. The majority of fermentation processes operate aerobically even though some fermentation processes operates anaerobically (i.e. in the absence of oxygen). Thus the provision of sterile oxygen or air in aerobic fermentation processes is vital for optimal growth of the organism as well as optimum product yield.
  • Baffles: Baffles are structures that are connected to impellers and they help to eliminate the formation of vortexes in the fermentation medium. Baffles prevent the upward throw of fermentation medium and their deposition on the sides of the fermenter. They help to break up air bubbles in the growth chamber of the fermenter. Baffles also assist in the thorough mixture of the nutrients and air or oxygen in the fermentation vessel.
  • Sensors: Sensors are structures fitted to a fermentation vessel which help to control environmental parameters such as pH and temperature. They also help to monitor the level of fermentation medium in the fermenter. Sensors help to monitor some of the critical parameters of the fermentation process; and thus help to ensure that the fermentation process is being operated in an optimal manner.
  • Fluid pumps: Fluid pumps are structures through which nutrients are introduced into the fermenter. They also serve as route via which buffers (acid or base) are introduced into the fermentation vessel in order to control the pH of the fermentation process.
  • Computer system: Most fermentation vessels are usually automated, and thus fitted with computer systems or monitors that monitor the real fermentation process. Computer units help to monitor the critical parameters of the fermentation vessel so that factors such as pH, temperature, gases, oxygen, metabolite and wastes can be effectively controlled for optimal microbial growth and product yield. Computers are necessary in the regulation and effective management of fermentation processes. Computerization of fermentation processes reduces manual labour and thus saves cost of production. It reduces human errors possible in fermentation processes. Computerization also helps to ease the work of the operators and it also provide avenues through which important changes could be made as the fermentation process progresses.

Further reading

Bushell M.E (1998). Application   of   the   principles   of   industrial   microbiology   to   biotechnology (ed. Wiseman, A.) Chapman and Hall, New York.

Byong H. Lee (2015). Fundamentals of Food Biotechnology. Second edition. Wiley-Blackwell, New Jersey, United States.

Frazier W.C, Westhoff D.C and Vanitha N.M (2014). Food Microbiology. Fifth edition. McGraw-Hill Education (India) Private Limited, New Delhi, India.

Jay J.M (2005). Modern Food Microbiology. Fourth edition. Chapman and Hall Inc, New York, USA.

Bushell M.E (1998). Application   of   the   principles   of   industrial   microbiology   to   biotechnology (ed. Wiseman, A.) Chapman and Hall, New York.

Farida A.A (2012). Dairy Microbiology. First edition. Random Publications. New Delhi, India.

Nduka Okafor (2007). Modern industrial microbiology and biotechnology. First edition. Science Publishers, New Hampshire, USA.

Roberts D and Greenwood M (2003). Practical Food Microbiology. Third edition. Blackwell publishing Inc, USA.

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