Morphological and Metabolic Engineering of Yarrowia lipolytica to Increase β-Carotene Production

Abstract

The oleaginous yeast Yarrowia lipolytica represents an environmentally friendly platform cell factory for β-carotene production. However, Y. lipolytica is a dimorphic species that can undergo a yeast-to-mycelium transition when exposed to stress. The mycelial form is unfavorable for industrial fermentation. In this study, β-carotene-producing Y. lipolytica strains were constructed via the integration of multiple copies of 13 genes related to the β-carotene biosynthesis pathway. The β-carotene content increased by 11.7-fold compared with the start strain T1. As the β-carotene content increased, the oval-shaped yeast form was gradually replaced by hyphae, implying that the accumulation of β-carotene in Y. lipolytica induces a morphological transition. To relieve this metabolic stress, the strains were morphologically engineered by deleting CLA4 and MHY1 genes to convert the mycelium back to the yeast form, which further increased the β-carotene production by 139%. In fed-batch fermentation, the engineered strain produced 7.6 g/L and 159 mg/g DCW β-carotene, which is the highest titer and content reported to date. The morphological engineering strategy developed here may be useful for enhancing chemical synthesis in dimorphic yeasts.

Advances in Metabolic Engineering Paving the Way for the Efficient Biosynthesis of Terpenes in Yeasts

“…In the resulting strain, the β-carotene production was significantly increased to the highest titer reported so far, reaching 7.6 g/L. 124 5.2. Adaptive Laboratory Evolution.…”

“…For example, Liu et al proposed morphological engineering to transform the Y. lipolytica mycelial phenotype, which is unfavorable for industrial fermentation, back to the oval yeast form by deleting the CLA4 and MHY1 genes. In the resulting strain, the β-carotene production was significantly increased to the highest titer reported so far, reaching 7.6 g/L …”

Improvement in l-ornithine production from mannitol via transcriptome-guided genetic engineering in Corynebacterium glutamicum

“…Fed-batch fermentation is generally used for performance evolution of engineered strains, which frequently produce higher titers of valuable compounds [ 36 , 37 ]. For instance, C. glutamicum produced l -proline at a titer of 120.18 g/L [ 38 ].…”

Production of natural colorants by metabolically engineered microorganisms

“…After enhancing the flux towards the MVA pathway and thus lycopene formation, the genes related to unsaturated fatty acid production and lipid droplet formation were overexpressed. This lipid engineering strategy was particularly effective in oleaginous microorganisms such as Y. lipolytica, leading to high-level production of astaxanthin (858 mg/l) [29] and β-carotene (7.6 g/l) [38]. Considering that such lipid droplet coproduction strategies have been suggested only recently, it is expected that more examples on the enhanced production of natural colorants will appear using these strategies.…”