Abstract: 【Abstract】 Objective To investigate the inhibitory effect of deoxyribonucleaseⅠ （DNaseⅠ） on Cutibacterium acnes biofilms. Methods Cutibacterium acnes biofilms were constructed, and then were divided into 4 groups （negative control group, 5, 10 and 20 U/ml DNaseⅠ groups） to be treated with DNaseⅠ at different concentrations of 0, 5, 10 and 20 U/ml respectively. The biofilm viability was evaluated by tetrazolium salt colorimetric assay, the biofilm content was determined by crystal violet staining-based semi-quantitative analysis, the biofilm structure was observed by confocal laser scanning microscopy, and the live/dead bacteria ratio was calculated. One-way analysis of variance was used to analyze differences between groups. Results After the treatment with DNaseⅠ, the biofilm viability was significantly inhibited in the 5, 10 and 20 U/ml DNaseⅠ groups （1.882 ± 0.421, 1.653 ± 0.287, 1.473 ± 0.154, respectively） compared with the negative control group （2.668 ± 0.245）, and the inhibitory effect was gradually enhanced with the increase in concentrations of DNaseⅠ（F = 9.68, P = 0.005）. Crystal violet semi-quantitative analysis showed that the biofilm content was also significantly lower in the 5, 10 and 20 U/ml DNaseⅠ groups （1.039 ± 0.003, 0.489 ± 0.079, 0.147 ± 0.034, respectively） than in the negative control group （1.359 ± 0.071）, and the higher the DNaseⅠ concentration, the lower the biofilm content （F = 174.40, P < 0.001）. Confocal laser scanning microscopy showed that the biofilm structure was destroyed in the 5, 10 and 20 U/ml DNaseⅠ groups compared with the negative control group, and the higher the DNaseⅠ concentration, the more severe the destruction of biofilm structure. Additionally, the live/dead bacteria ratio was significantly lower in the 5, 10 and 20 U/ml DNaseⅠ groups （2.303 ± 0.457, 1.534 ± 0.526, 1.263 ± 0.354, respectively） than in the negative control group （4.475 ± 0.146）, and the ratio decreased with the increase in concentrations of DNaseⅠ（F = 56.75, P < 0.000 1）. Conclusion DNaseⅠ had a destructive effect on the structure of Cutibacterium acnes biofilms, and could inhibit their viability.

Key words: Cutibacterium acnes, Biofilms, DeoxyribonucleaseⅠ