Gelana Urgesa,Liushen Lu,Jinwei Gao,Lichun Guo,Ting Qin,Bo Liu,Jun Xie,Bingwen Xi
Aeromonas hydrophilacan be a substantial concern, as it causes various diseases in aquaculture. An effective and green method for inhibitingA. hydrophilais urgently required. Emodin, a naturally occurring anthraquinone compound, was exploited as a photo-antimicrobial agent againstA. hydrophila. At the minimum inhibitory concentration of emodin (256 mg/L) to inactivateA. hydrophiliain 30 min, an 11.32% survival rate was observed under 45 W white compact fluorescent light irradiation. In addition, the antibacterial activity under natural sunlight (0.78%) indicated its potential for practical application. Morphological observations demonstrated that the cell walls and membranes ofA. hydrophilawere susceptible to damage by emodin when exposed to light irradiation. More importantly, the photoinactivation ofA. hydrophilawas predominantly attributed to the hydroxyl radicals and superoxide radicals produced by emodin, according to the trapping experiment and electron spin resonance spectroscopy. Finally, a light-dependent reactive oxygen species punching mechanism of emodin to photoinactivateA. hydrophilawas proposed. This study highlights the potential use of emodin in sunlight-mediated applications for bacterial control, thereby providing new possibilities for the use of Chinese herbal medicine in aquatic diseases prevention.
Bin Wu,Xiangyun Wang,Fangyu Zhang,Yunjian Ma,Yonghua Wang
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.
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