High-cell-density cultivation (HCDC) is a process that improves the formation of microbial biomass and products. It can be used for microorganisms such as bacteria, archaea, and yeasts. HCDC can make the fermentation process faster and more robust by increasing its volumetric productivity. 

Here are some things to consider when using HCDC:

• Oxygen transfer: Microbial high cell density cultures have a high demand for oxygen, and the oxygen transfer rate of the bioreactor determines the maximum biomass concentration. The solubility of oxygen decreases as cell densities increase due to the higher viscosity of the cell suspension. To improve oxygen transfer, you can use an aeration membrane, disposable spargers and baffles, or vibrate the medium. 
• Feeding: There are different feeding strategies that can be used, including constant, increased, and exponential feeding. 
• Cell density: If the seeding density is too high, cells can reach overconfluence quickly, which can impair proliferation and cause cells to detach from the substrate. This can lead to non-reproducible experimental conditions. 
• Trace elements: Some cultivation media for HCDC of Escherichia coli lack essential trace elements like molybdenum, selenium, and nickel. These elements are required for the function of the FHL pathway.