Control Micro fermentation

There several DO probes available. Some well-known branded fermenters, like New Brunswick, Bioflo series and the B. Braun Biotstat B fermenters are equipped with a DO meter. This unit has a 2 litre fermentation vessel equipped with DO meter and pH probe, antifoam sensor and level controllers for harvesting culture. The concentration of DO in the media is a function of temperature. The higher operating temperature would decrease the level of DO. A micro-sparger is used to provide sufficient small air bubbles. The air bubbles are stabilized in the media and the liquid phase is saturated with air. The availability of oxygen is major parameter to be considered in effective microbial cell growth rate. 

In biotechnology man makes use of these multiple opportunities offered by nature for the synthesis of materials. In general, all biotechnical processes are based on the reaction of a living cell either directly with the raw material (fermentation with intact micro-organisms, e.g. mediated by starter cultures) or these reactions take place inside well controlled technical equipment, so-called bioreactors. 

When isolated biochemical catalysts (enzymes) or specially selected cultures of micro-organisms are to be used and more precisely defined reaction conditions are required, the biotechnological system demands a better controlled environment. Modem biotechnology, therefore, can be addressed as a refinement and further development of spontaneous fermentation with raw material inherent organisms. 

All biochemical reactions are enzyme-mediated. The rate of an enzyme reaction depends on the substrate concentration at the location of the enzyme and thereby on the diffusion rate of a substrate to the enzyme. It is therefore important to permanently obtain an intimate contact between a cell or enzyme and substrate molecules. Additionally, the product generated in the bioreactor has to be extracted because it may under certain conditions inhibit its own production. In some processes there may also be even a prepurification in the bioreactor itself. If living micro-organisms have to be applied, it is necessary to provide sufficient nutrition and respiration gases in case of aerobic fermentation. All other reaction parameters such as temperature, pH-value and reaction time have to be controlled precisely. In many cases (generally with modem processes) the maintenance of microbiological integrity (sterile process) is absolutely mandatory for a successful fermentation. 

There is a millennium of history of enzyme application in the improvement of food. Cheese production, the production of seasoning sauces, fermentation of raw sausages, tea and tabacco fermentation are only a few examples. In all these cases enzymes have been applied as a part of the living enzyme containing micro-organisms. Today many of those enzymes are characterized and available as pure substances in high concentration. They facilitate a precise operation and safe control of the manufacturing process. 

Microbial fermentations must be tightly controlled to ensure optimal growth of micro-organisms and efficient production of enzymes. As shown in Fig. 4, a modern fermentor will allow operators to control the temperature, pH, redox potential, and dissolved... 

The determination of antibiotics in fermentation broths is important for control of an antibiotic fermentation. Antibiotics are usually determined by microbioassay based on turbidimetric or titrimetric methods. However, these methods require a long time for cultivation of bacteria (9). Therefore, rapid and continuous determination of antibiotics produced is difficult by the micro-bioassay. 

LA may also be found in various processed foods, usually either as a pH-adjusting ingredient or as a preservative (either as antioxidant or for control of pathogenic micro-organisms). It may also be used as a fermentation booster in rye and sourdough breads. 

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