Biobased sunscreen fabrication using Zn-porphyrins from engineered Corynebacterium glutamicum

Abstract

Porphyrin is a heterocyclic macromolecule that strongly absorbs UV-visible light. Here, Corynebacterium glutamicum was engineered for the secretory production of Zn-porphyrins (Zn-PPs), and the sunscreen effect of Zn-PPs on broad-spectrum UV irradiation was evaluated. The overexpression of the heme exporter HrtBA and the addition of ethambutol in fermentation improved the secretory production of Zn-PPs in C. glutamicum. The fed-batch fermentation of the engineered strain showed a production titer of Zn-PPs of 346.59 ± 17.38 mg L⁻¹, including 294.81 ± 14.94 mg L⁻¹ secreted Zn-PPs, which was the highest in C. glutamicum reported to date. The cream containing Zn-PPs showed a sunscreen effect in both the UV-A and UV-B regions, especially with superior absorption in the UV-A region. Zn-PPs also showed hydroxyl radical scavenging activity. The Zn-PPs cream blended with lignins to complement the UV-B absorption enhanced the blocking effect on the broad spectrum. These results demonstrate that Zn-PPs have promising potential as biorenewable sunscreens.