The modern catering industry and factories produce a large amount of waste oil every day, and most of these oils are discharged into water bodies or landfills in waste treatment plants, causing environmental pollution and aggravating the greenhouse effect. Meanwhile, squalene, as a high-value substance for cosmetics, medical and health care products, has fewer sources, and its biosynthesis raw material is acetyl coenzyme A. Waste oil is broken down into fatty acids and glycerol by lipolytic yeast lipase, and the free fatty acids FFA and glycerol enter into the intracellular compartment to provide a large amount of synthesized raw material. However, because squalene as a yeast intermediate product will be converted to ergosterol for cholesterol synthesis by cyclase at the proximal endoplasmic reticulum, the squalene back-end pathway could not be knocked out because of the necessity of cholesterol. The MVA pathway in the cytoplasm is less efficient, Ac-CoA as raw material for the competition pathway; squalene has cytotoxicity, a large amount of presence in the cytoplasm will lead to yeast death, so a large number of synthesized squalene needs to be wrapped with the cytosolic membrane, therefore, we consider the synthesis of squalene in the compartmentalized synthesis of squalene, the use of yeast subcellular structure of the peroxidase, can be wrapped in the product of squalene, and also to prevent the transformation of squalene by the cyclooxygenase in the cytoplasm.

In order to greatly increase the yield of squalene and alleviate the redox stress caused by the continuous synthesis of squalene, it is necessary to increase the synthesis capacity of NADPH and overexpress the key enzyme of the β-oxidation pathway.

Considering the complexity of the actual application environment, it is necessary to combine the results of the subsequent HP visits to cosmetic raw material synthesizing factories and cosmetic listing and approval bureaus to further strengthen the resilience of Yarrowia lipolytica.