Study of the Effect of Photobiomodulation on the Human Intestinal Microbiota In Vitro under Normal Conditions and after Cryopreservation

Abstract

Violation of the composition of the human intestinal microbiota is a key factor in the development of many diseases. Existing correction methods (probiotics, microbial transplantation, etc.) are often invasive or insufficiently effective. Photobiomodulation is a promising noninvasive approach, but its direct effect on the microbiota in vitro has not been studied. The aim of this work was to investigate the effect of photobiomodulation with red (660 nm) and near-infrared (940 nm) light on the restoration of microbiota after cryogenic damage used as a stress model. The whole microbiota of donors isolated from stool samples and a pure culture of Bifidobacterium breve were frozen in liquid nitrogen, which led to the death of ~50% of cells. The samples were thawed and irradiated with light in the low dose range of 10–600 J/m². The viability of microorganisms was assessed using a LIVE/DEAD dye test kit. For B. breve, the growth dynamics under anaerobic conditions during cultivation on a microplate was also evaluated. Photobiomodulation did not significantly affect the survival of intact microorganisms. On the contrary, near-infrared irradiation significantly (p < 0.05) increased the viability of microorganisms after cryopreservation, both intestinal microbiota with a maximum effect of +43% at a dose of 40 J/m² and B. breve with maxima of +10% (p < 0.05) at doses of 40 and 80 J/m². For B. breve, growth stimulation was noted by 8% (p < 0.05) during cultivation. Irradiation with 660 nm red light had no pronounced effects. It has been shown for the first time that photobiomodulation with near-infrared light is able to effectively restore viability in experiments on human microbiota and culture of B. breve microorganisms in vitro after cryogenic damage. Cryopreservation can be used as a model of damage to the intestinal microbiota to screen for physical and chemical factors that potentiate the recovery of microorganisms. The results obtained open up prospects for the development of noninvasive methods of rehabilitation and treatment of diseases associated with human dysbiosis based on transabdominal photobiomodulation.