Compound mutagenesis boosts β-carotene biosynthesis in Neurospora crassa: ATP synthase mutation and enzymes...

Neurospora crassa is a kind of biosafe fungus capable of synthesizing β-carotene from diverse feedstocks. However, the yield is constrained by the capacity of N. crassa strain. To improve the β-carotene synthesis ability, ultraviolet (UV), chemical (diethyl sulfate), and heavy ion beam were integratively employed in this study to breed N. crassa strain with high β-carotene producing performance. A mutant N. crassa strain exhibited 112.02 μg/g of β-carotene yield after 3 days fermentation, which was 325.5 % higher than initial strain. Subsequently, the key genes and metabolic pathways involved in β-carotene synthesis and substrates utilization was analyzed through whole-genome sequencing, and the results revealed that a synonymous nucleotide mutation on the ATPeV1A gene altered the RNA structure of ATP synthase and increased the ATP content. In addition, the significantly higher activities of protease, cellulase, and xylanase were observed in the mutant strain, further explained the speculation of high β-carotene yield.