High-throughput screening of lycopene-overproducing mutants of Blakeslea trispora by combining ARTP mutation with microtiter plate cultivation and transcriptional changes revealed by RNA-seq

Abstract

Random mutagenesis is still the main strategy for increasing the lycopene yield from Blakeslea trispora because of its complex, unclear genetic regulation. In this study, an effective mutation breeding method was established to obtain lycopene-overproducing mutants, and the transcriptional changes between the mutant and parent strains were then revealed by RNA-seq. After ARTP mutation and preliminary screening on solid plates, 50 color mutants were simultaneously inoculated into a microtiter plate-based system (MTPS) and traditional flasks to estimate the dependability of the high-throughput screening method. As expected, a significant linear correlation (R2 = 0.924) was observed between the absorbance of pigment in the MTPs and lycopene production in flask fermentation. A mutant (WY-239) showing a maximum lycopene concentration of 21.80 ± 1.58 mg/g was obtained, which represented a 56.27 % increment compared with the parent strain. Transcriptomic analysis showed that the carbon metabolism flowed more intensively to acetyl-CoA and then to lycopene in the WY-239 mutant compared with the parent strain. Some primary metabolic and sexual activity may be correlated with lycopene biosynthesis. The mutation breeding method could also be used as a reference for breeding other filamentous fungi, and the findings of RNA-seq can serve as a basis for metabolic engineering.