Objective At present, the most commonly used photosensitizers in photodynamic therapy are still chemical photosensitizers, such as porphyrin and methylene blue, in order to specifically target cellular tissues, and thus poison cells, chemical photosensitizers need to use antibody conjugation or a transgenically encoded tag with affinity for the modified photosensitizing ligand, e.g. FlAsH, ReAsh or Halo Tag. Gene-encoded photosensitizers can directly poison cells by targeting specific cell compartments or organelles. However, currently developed gene-encoded photosensitizers have low reactive oxygen species production and low cytotoxicity, so it is necessary to continue to develop and obtain photosensitizers with higher reactive oxygen species production for the treatment of microbial infections and tumors.Methods In this study, we developed a photosensitizer LovPSO2 based on the light-oxygen-voltage (LOV) structural domain of phototropin-1B-like from Oryza sativa japonica. LovPSO2 was expressed in E. coli BL21(DE3) and purified to obtain protein samples, the purified protein samples were added 3 μmol/L singlet oxygen probe of SOSG and 5 μmol/L superoxide anion probe of DHE after fixed to A₄₄₅=0.063±0.003, respectively, then measured every 2 min of singlet oxygen production for 10 min and every 1 min of superoxide anion production for 5 min under blue light irradiation at 445 nm, 70 μmol·m^-2·s^-1.Results The results showed that LovPSO2 could produce a large amount of singlet oxygen under blue light irradiation at 445 nm, 70 μmol·m^-2·s^-1, and its singlet oxygen quantum yield was 0.61, but its superoxide anion yield was low, so in order to improve the superoxide anion yield of LovPSO2, a mutant with a relatively high superoxide anion yield was obtained by further development and design on its basis LovPRO2. The stability of proteins is crucial for research in drug development and drug delivery, among others. Temperature and light are the key factors affecting the production of reactive oxygen species (ROS) by photosensitive proteins and their stability, while the temperature in cell culture and mammals in vivo is about 37°C, and the temperature inside tumor cells is about 42-45°C. Therefore, we further analyzed the photostability of miniSOG, SOPP3, LovPSO2, and LovPRO2 and their thermostability at 37℃ and 45℃. The analysis of proteins thermostability showed that LovPSO2 and LovPRO2 had better thermostability at 37℃ and 45℃, respectively. Analysis of the photostability of the proteins showed that LovPRO2 had better photostability. In addition, to further determine the phototoxic effects of photosensitizers, LovPSO2 and LovPRO2 were expressed in E. coli BL21(DE3) and HeLa cells, respectively. The results showed that LovPSO2 and LovPRO2 had better phototoxicity to E. coli BL21(DE3) under blue light irradiation, and the cellular phototoxicity lethality was as high as 90% after 30 min of continuous light irradiation, but the phototoxicity was weaker in HeLa cells. The reason for this result may be that the intracellular environment exacerbated the photobleaching of FMN encapsulated by LovPSO2 and LovPRO2, respectively, which attenuated the damage of reactive oxygen species to animal cellular tissues, limiting its use as a mechanistic tool to study oxidative stress.Conclusion LovPSO2 and LovPRO2 can be used as antibacterial photosensitizers, which have broader application prospects in the food and medical fields.