Creation of an Industrial Strain With High Melanin Production and UV Tolerance by Gene Editing.

produces insecticidal crystal proteins (ICPs) which exhibit strong insecticidal toxicity. But when used in the field, ICPs would be destroyed by ultraviolet (UV) radiation in sunlight, thus decreasing the insecticidal activity and shortening the persistence. To improve the duration of preparations, we endowed a highly toxic industrial HD-1 with UV tolerance by making it produce melanin, a pigment that absorbs UV radiation. In , melanin is derived from homogentisate (HGA), an intermediate in the tyrosine pathway. And the absence of homogentisate-1,2-dioxygenase (HmgA) will lead to the formation of melanin. In this study, we used the CRISPR/Cas9 system to knock out the gene and obtained a melanin-producing mutant HD-1-Δ from strain HD-1. The melanin yield by mutant HD-1-Δ reached 3.60 mg/mL. And the anti-UV test showed that melanin serves as a protection to both the organism and the ICPs. After UV irradiation for 3 h, mutant HD-1-Δ still had an 80% insecticidal activity against the cotton bollworm, , while the control line only had about 20%. This study creates a light-stable biopesticide prototype based on a classic industrial strain that can be applied directly and takes the melanin-producing strain as a concept to improve the preparation validity.