Test results

Nanobubbles (Ultrafine bubbles) are known to have a sterilization effect. In most cases, the effectiveness of the sterilization effect has been demonstrated using bubbles containing ozone or other sterilizing agents, but verification had not been conducted with hydrogen-encapsulated Nanobubbles.

Therefore, in this joint research with the Faculty of Nutrition at Kobe Gakuin University, we used the Nanobubbles, NanoGAS®️, manufactured using the proprietary technology developed and patented by Shinbiosis Corporation, to verify the sterilization effect of hydrogen-encapsulated Nanobubbles (Hydrogen NanoGAS®️) water and ozone-encapsulated Nanobubbles (Ozone NanoGAS®️) water through a suspension test.

[Verification method]

0.1 mL of a bacterial solution adjusted to a concentration of 1,000 CFU/mL for S. aureus (Staphylococcus aureus) and E. coli (Escherichia coli), respectively, was suspended in 0.9 mL each of Hydrogen NanoGAS®️ water (undiluted solution), Ozone NanoGAS®️ water (undiluted solution), Injection Water (IW), and Saline. Immediately after suspension, the resulting suspension was plated onto two agar plates (0.1 mL per plate). After suspension, the samples were reacted at 37∘C, and were similarly plated onto two agar plates at 1, 3, 6, and 9 hours post-suspension. All agar plates were cultured at 37∘C, and the number of bacteria was counted after 24 hours for E. coli and 48 hours for S. aureus. The bacterial survival rate was calculated using the following formula (adopting the average value of the two plates).

【Results and Discussion】

Figure: Time-dependent changes in the bacterial survival rate of E. coli (left) and S. aureus (right)

(#, p<0.01 compared with exposure to saline; *, p<0.05 compared with exposure to IW. Data are expressed as the mean ± S.E.M (n = 3-5). N.D.:Not detected.)

Regardless of the encapsulated gas, the bacterial survival rate of E. coli significantly decreased compared to IW after 6 hours in both the Hydrogen and Ozone NanoGAS®️ water groups, and the bacterial survival rate of S. aureussignificantly decreased compared to IW and Saline after 3 hours.

The time required for the sterilization effect to manifest in our results was longer compared to other research reports (Yamaguchi et al., 2021). Since the number of Nanobubbles in the NanoGAS water was smaller compared to other reports, it is possible that the sterilizing power of Nanobubbles in the suspension method is dependent on the bubble concentration. Furthermore, while the sterilizing effect of Nanobubbles is generally thought to be significantly influenced by the encapsulated gas, a sterilizing effect was observed even in Hydrogen NanoGAS®️ water, which contains non-sterilizing hydrogen gas, under the current conditions. This suggests that the increased activity of the bacteria in the 37∘Cenvironment led to a higher frequency of contact with the bubbles, and the sterilization effect may have been achieved through the collapse of the bubbles themselves and the associated energy.

Further research is required regarding the relationship between Nanobubbles’ collapse, encapsulated gas, and ROS(Reactive Oxygen Species) generation concerning sterilization.

【Publication Information】

Morishita R, Itoh S, Takeda-Morishita M. (2022) Biocontrol Sci. 27, pp. 139-142.
Evaluation of Bactericidal Effects of H₂– and O₃-filled Ultrafine Bubbles Water.
https://doi.org/10.4265/bio.27.139

原著論文　NanoGAS　懸濁除菌効果