Final answer:
The critical component, often a carbon source, is added continuously in a chemostat to maintain a continuous culture and keep the microorganisms in the logarithmic phase of growth without excess substrate.
Step-by-step explanation:
Frequently a critical component in the medium, often the carbon source, is added continuously so that the microorganisms will not have excess substrate available at any given time. This approach is used in a chemostat, which maintains a continuous culture by adjusting the addition and removal of fluids to maintain the culture in the logarithmic phase of growth. This phase is where growth occurs at the fastest rate, and the method ensures that bacteria have a steady supply of nutrients without reaching toxic concentrations and that waste products are diluted.
Factors that limit microbial growth include the availability of nutrients and proper environmental conditions such as temperature and pH. A bioreactor can be selected based on the product required, and it usually contains a mix of nutrients like carbohydrates, proteins, and inorganic salts, sometimes supplemented with vitamins to meet the specific needs of the microorganisms.