It is well documented that blue light absorption by bacterial chromophores triggers downstream production of reactive oxygen species (ROS), which in turn results in bacterial cell death. To elucidate the importance of chromophores in the bactericidal effect of blue light, and to determine whether blue light absorption per se or the presence of porphyrins known to engender ROS is crucial in blue light treatment, we studied the effect of 450 nm pulsed light on Streptococcus agalactiae, also known as Group B Streptococcus (GBS) strain COH1. GBS does not synthesize porphyrins but has a blue light-absorbing chromophore, granadaene. We irradiated planktonic cultures of GBS with or without exogenous chromophore supplementation using either protoporphyrin IX (PPIX), coproporphyrin III (CPIII), Nicotinamide adenine dinucleotide (NAD), reduced nicotinamide adenine dinucleotide (NADH), Flavin adenine dinucleotide (FAD), or Flavin mononucleotide (FMN). Quantification of surviving bacterial colonies, presented as percent survival and CFU/mL (log₁₀), showed that (1) 450 nm blue light does not suppress the growth of GBS, even though its endogenous chromophore, granadaene, absorbs light in the 450 nm spectrum. (2) The addition of either of the two exogenous porphyrins, PPIX or CPIII, significantly suppressed GBS, indicating the importance of porphyrins in the antimicrobial action of blue light. (3) Adding exogenous FMN or FAD, two known absorbers of 450 nm light, minimally potentiated the bactericidal effect of blue light, again confirming that mere absorption of blue light by chromophores does not necessarily result in bacterial suppression. (4) Irradiation of GBS with or without NAD+ or NADH supplementation—two weak absorbers of 450 nm light—minimally suppressed GBS, indicating that a blue light-absorbing chromophore is essential for the bactericidal action of blue light. (5) Collectively, these findings show that in addition to the presence of a blue light-absorbing chromophore in bacteria, a chromophore with the right metabolic machinery and biochemical structure, capable of producing ROS, is necessary for 450 nm blue light to suppress GBS.

有充分的文献记载，细菌生色团吸收蓝光会触发下游产生活性氧（ROS），从而导致细菌细胞死亡。为了阐明发色团在蓝光杀菌作用中的重要性，并确定蓝光本身的吸收或已知引起ROS的卟啉的存在对蓝光处理至关重要，我们研究了450 nm脉冲光对链球菌的影响无乳杆菌，也称为B组链球菌（GBS）菌株COH1。GBS不合成卟啉，但具有吸收蓝色光的发色团，即格拉那烯。我们用原卟啉IX（PPIX），辅卟啉III（CPIII），烟酰胺腺嘌呤二核苷酸（NAD），还原烟酰胺腺嘌呤二核苷酸（NADH），黄素腺嘌呤二核苷酸（FAD）辐照了GBS的浮游细菌培养物，无论是否添加外生色团单核苷酸（FMN）。存活细菌菌落的定量，以存活百分比和CFU / mL表示（log ₁₀）表明（1）450 nm的蓝光不能抑制GBS的生长，即使其内生发色团Granadaene吸收了450 nm光谱中的光。（2）两种外源卟啉PPIX或CPIII的加入均显着抑制了GBS，表明卟啉在蓝光的抗菌作用中具有重要意义。（3）添加两种外来的FMN或FAD，两种已知的450nm光的吸收剂，最小程度地增强了蓝光的杀菌作用，再次证实发色团仅吸收蓝光并不一定导致细菌抑制。（4）辐照添加或不添加NAD +或NADH的GBS（两个450 nm光的弱吸收剂）对GBS的抑制作用最小，表明吸收蓝光的发色团对于蓝光的杀菌作用至关重要。（5）集体地，