CONCLUSIONS

The key contribution of this study was the analysis of the response of spores to sodium hypochlorite at the single-cell level. Using single-cell techniques, our results revealed that sodium hypochlorite inactivates spores by degrading the spore shell, damaging germination proteins, breaking the permeability barrier, and damaging DNA. Upon contact with spores, sodium hypochlorite reacted with the shell protein layer, gradually dissolving the shell until it was completely degraded and the attached budding proteins were destroyed. Subsequently, it damaged the cortex, endosperm, and other structures of the spores, destroying the permeability barrier and causing the spores to release CaDPA. Sodium hypochlorite entered the interior of the spores, causing damage to DNA and other substances and ultimately leading to spore inactivation. In addition, with the prolongation of sodium hypochlorite treatment, the inhibitory effects on germination and growth increased, and damage to the structure of spores was more serious. Long-term sodium hypochlorite treatment will continue to degrade other structures of the spores and even the entire spore. The volume of the spores may decrease dramatically after degradation, making the acquisition of single-cell Raman spectra difficult; therefore, we controlled the treatment time to less than 20 min. The effects of increasing the treatment time on spores need to be investigated in the further.