Fermentation engineering has entered the category of bioengineering through decades of practice in fermentation industrial production. Fermentation engineering is mainly composed of three parts: upstream engineering, midstream engineering and downstream engineering.

The upstream engineering includes the selection and breeding of excellent strains, the determination of optimum fermentation conditions (pH, temperature, DO and nutrients), and the preparation of nutrients.

The midstream engineering mainly refers to the process technology of culturing cells and producing metabolites in a fermenter under the optimum fermentation conditions.

The downstream engineering refers to the technology of separating and purifying products from fermentation broth, including solid-liquid separation technology (centrifugation, filtration, precipitation, etc.), cell disruption technology (ultrasonic, high-pressure shear, osmotic pressure, surfactants, lysozyme, etc.), protein purification technology (chromatography, ultrafiltration, etc.) and product packaging processing technology (freeze drying, filling, etc.).