Figures captions
Fig. 1 Metabolic pathway for squalene synthesis in oleaginous yeast. MnDH, mannitol dehydrogenase; HXK, hexokinase; MAE1, malic enzyme; ACL2, ATP citrate lyase; IDP2, cytosolic NADP-specific isocitrate dehydrogenase; UGA2, succinate semialdehyde dehydrogenase; PYC1, pyruvate carboxylase; PDC1, pyruvate decarboxylase; ALD, aldehyde dehydrogenase; PDH, pyruvate dehydrogenase complex; ACS, acetyl-CoA synthase; FAS1 and FAS2, fatty acid synthase; ACC1, acetyl-CoA carboxylase; HMG, HMG-CoA reductase; Erg 10, acetoacetyl-CoA thiolase; Erg 12, mevalonate kinase; Erg 8, phosphomevalonate kinase; MVD, mevalonate pyrophosphate decarboxylase; Erg 20, farnesyl pyrophosphate synthetase; GPS, geranyl pyrophosphate synthase; SQS, squalene synthase.
Fig. 2 Comparison of different HMG-CoA reductase and identification of rate-limiting steps of endogenous mevalonate pathway in Y. lipolytica .
Fig. 3 Enhancement of NAPDH and acetyl-CoA precursor pathways to improve squalene production. ScPDC1, pyruvate decarboxylase fromS. cerevisiae ; EcPuuc, aldehyde dehydrogenase from E. coli . Other genes are native genes from Y. lipolytica and detailed gene annotation could be found in Fig. 1.
Fig. 4 Improving squalene production by controlling pH and C/N ratio with cerulenin supplementation in glucose-minimal media. Fermentation profile of glucose consumption, mannitol, dry cell weight, citric acid and squalene accumulation for strain HLYaliS02cultivated in glucose-minimal media conditioned with PBS buffer and supplemented with 1 mg/L cerulenin (A). Fermentation profile of glucose consumption, mannitol, dry cell weight, citric acid and squalene accumulation for strain HLYaliS02 cultivated in glucose-minimal media conditioned with PBS buffer, supplemented with 1 mg/L cerulenin and C/N ratio 40:1 (B).