Computer-aided fermentation

The application of direct digital control of fermentation processes began in the 1960 s. Since then, many corporations have developed computer-aided fermentation in both pilot and commercial plants. Unfortunately, these proprietary processes have almost never been published, due to corporate secrecy. Nevertheless, recent advances in computer and sensing technologies do provide us vwth a great deal of information on fermentation. This information can be used to design optimal and adaptive process controls. 

The first persons to point out the possibility of computer monitoring of indirectly measured parameters were Yamashito, Hisashi, and Inagaki in 1969 (2). The method was described in a U.S. Patent in 1975 (3). Examples of the application of computer-aided indirectly measured parameters to the control and optimization of batch-fed Baker s Yeast fermentation were described by Jefferis and Humphrey in 1973 (4) and by Wang, Cooney, and Wang in 1977 (5). Background and detailed history of this application can be found in the review by Humphrey (1). The work to be discussed in this report is another example of computer-aided indirectly measured cell biomass and growth rate and the use of this information in the feed back control of the carbon substrate, ethanol, in a process for the production of a yeast single cell protein (SCP). 

There are a few generally accepted strategies to select suitable growth conditions. Tormo et al. reported a computer-aided HPLC-based method for the selection of production media for actino-mycete strains. Another strategy is to grow the strains in a multitude of different media or to cultivate them with different fermentation conditions (e.g., of aeration, stirring, and pH). The starting point for media optimization can be the completely random selection of media or the selection of specific media with the most diverse compositions possible. 

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