Table 2.

Effect of MS-SOD on 5-FU-induced changes in mouse bacterial flora

	Bacteroidetes	Firmicutes	Proteobacteria	Actinobacteria	Tenericutes	Verrucomicrobia
Control	57 ± 9.42	42.39 ± 9.51	0.22 ± 0.13	0.35 ± 0.21	0.02 ± 0.02	0 ± 0
5-FU	50.76 ± 10.24	47.93 ± 10.64	0.86 ± 0.75	0.16 ± 0.11	0.16 ± 0.067##	0.12 ± 0.17#
5-FU + MS-SOD	69.21 ± 6.50*	27.95 ± 5.76*	2.48 ± 4.77	0.18 ± 0.11	0.17 ± 0.15	0 ± 0**

Animals were administered 50 mg/kg 5-FU via intraperitoneal injection once daily for 5 days (days 1 to 5), with or without 800 U/10 g MS-SOD coadministered daily. Feces were collected on day 6, and bacterial 16S rDNA was quantified via PCR. The data are shown as the mean (%) ± SD (%) values from 6 animals per group. ^#P < 0.05, ^##P < 0.01 vs. control; *P < 0.05, **P < 0.01 vs. animals treated with 5-FU only

According to the community abundance, species with significant differences in richness in microbial communities between different groups were found. At the phylum level, the relative abundance of Bacteroides in MS-SOD-treated mice was higher than that in the model group (P < 0.05), and the relative abundance of Firmicutes was lower than that in the model group (P < 0.05). In addition, The Verrucomicrobia population was significantly increased in the model group (P < 0.05) and was significantly decreased after MS-SOD administration (P < 0.01)