A Dual-Promotion Strategy to Enhance Photostability of Fatty Acid Photodecarboxylase for Efficient Alkane Biofuel Production

Photoinactivation has presented a substantial impediment to the practical implementation of fatty acid photodecarboxylase (FAP), despite its promising potential in the sustainable energy domain. In this study, a dual-promotion strategy for enhancing the photostability of FAP was used, including the introduction of internal reducing amino acids and the addition of external reducing agents. The best combination was to introduce the Cys mutation internally and add reduced glutathione (GSH) to the reaction system. The Cys mutants CvFAP-L173C, McFAP-S-A110C, and CsoFAP-S-L176C showed 2.65, 1.9, and 2.3-fold increased blue light half-life compared with their wild type, respectively. Notably, the Cys mutants performed significant photostability in a light-flow reactor containing 30 mM GSH, especially CsoFAP-S-L176C, which retained its functionality even after continuous reaction for 20 h, achieving a remarkable quantity of C15 alkane (200 mL, 6.9 mmol, conversion 93%). The positive impact of this strategy on FAPs underscores its considerable potential to enhance the photostability of FAPs and propel the application of FAPs in the field of biofuel synthesis.