The principle of speed control in microbial fermentation primarily focuses on regulating the rate of enzyme-catalyzed reactions within microorganisms. Enzymes are proteins that catalyze chemical reactions in living organisms, accelerating the reaction process without altering the total energy change. In microbial fermentation, the rate of enzyme-catalyzed reactions directly influences metabolite production rates and fermentation efficiency. Fast and stable enzyme-catalyzed reaction rates enhance fermentation efficiency, reduce fermentation time, and potentially improve product purity and yield.
Enzyme activity is significantly influenced by temperature. Each enzyme has an optimal temperature range where its activity is highest and the reaction rate is fastest. Therefore, regulating fermentation temperature controls the rate of enzyme-catalyzed reactions. For example, microorganisms requiring high-temperature fermentation need a suitable high-temperature environment to accelerate enzyme-catalyzed reactions, while those requiring low-temperature fermentation need lower temperatures to maintain enzyme activity.
Enzyme activity is also significantly influenced by pH. Each enzyme has an optimal pH range; deviations from this range reduce activity or even inactivate the enzyme. Therefore, adjusting the pH of the fermentation solution can regulate the rate of enzyme-catalyzed reactions. Regularly testing the pH of the fermentation solution and adding acid-base regulators as needed maintains optimal fermentation conditions.
Substrate concentration is a key factor influencing the rate of enzyme-catalyzed reactions. High substrate concentrations may cause substrate inhibition, reducing the reaction rate. However, excessively low substrate concentrations may limit the reaction rate. Therefore, controlling the dosage and addition rate of the substrate maintains an optimal concentration range.
Additionally, microorganisms require specific nutrients during fermentation to sustain growth and metabolic activity. Providing adequate nutrients enhances the rate and efficiency of enzyme-catalyzed reactions.