Metabolic engineering of Neurospora crassa for increasing carotenoids synthesis

Carotenoids are essential nutrient compounds with numerous biological functions. Neurospora crassa is a model filamentous fungus with orange pigmentation which is attributed to the accumulation of carotenoids containing neurosporaxanthin (NX) and neutral carotenoids (NC). To enhance carotenoids synthesis in N. crassa , isoprene diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) were increased using the genes, xylulose-5-phosphate phosphoketolase ( XPK ), phosphotransacetylase ( PTA ), and NADH-specific-3-hydroxy-3-methyl glutaryl coenzyme A reductase ( HMGR ), as single, fused and three combined expressions to channel more carbon source into the mevalonate pathway (MVP). The single ( PTA , XPK , HMGR ), fused ( PTA:HMGR & XPK:HMGR ) and three combined gene ( PTA with fused XPK:HMGR ) expressions in engineered fungal resulted in carotenoid titers with contents of NX accumulated up to 4.5 mg/g DW and NC up to 1.7 mg/g DW as compared to the wild-type with NX up to 1.54 mg/g DW and NC up to 0.8 mg/g DW. The optimized MVP with metabolic engineering methods is a key method to increase the synthesis of carotenoid and other active terpenoids crassa .