## 3 Results
### Effects of TA and LC on the Fecal Microbiota Composition in DSS-Treated Mice  
To measure the composition of the gut microbiota and the presence of beneficial bacteria, cDNA was extracted from the stool, and qPCR was performed. The Firmicutes/Bacteroides ratio, a representative indicator of intestinal condition, was optimized in the DTL group to closely resemble that of the control group (Figure 7A). Beneficial intestinal bacteria, including _Faecalibacterium prausnitzii_, _Akkermansia mucinipiha_, _Lactobacillus plantarum_, and _Lactobacillus casei_, were significantly increased in all groups compared to the DSS group (Figure 7B-F). The abundance of _Lactobacillus casei_ was particularly high in the LC-treated group, confirming the effectiveness of bacterial inoculation via oral gavage (Figure 7F). Moreover, _Lactobacillus reuteri_, known for its excellent immune effects, was  
Figure 5: Effects of TA and LC on mRNA levels of pro-inflammatory factors and tight junctions in DSS-treated mice. (**A**) Nfkb, (**B**) Cox-2, (**C**) Inos, (**D**) Muc2, (**E**) Zo-1, (**F**) Occludin, and (**G**) Claudin1 mRNA expressions in mice colon tissue. \(\beta\)-actin was used as the reference gene. Mice were fed experimental extracts (50 mg/kg bw/day) or PBS via oral gavage for 30 days. Subsequently, from day 17 to day 24, 3% dextran sulfate sodium (DSS) was provided in the drinking water, and _Lactobacillus casei_ (1 \(\times\) 10\({}^{8}\) cells/100 \(\mu\)L) was administered from day 21 to day 28. All data are expressed as mean \(\pm\) SD (\(n\) = 8/group). * \(p\) < 0.05,  
significantly increased in the DTA and DTL groups (Figure 7D). This highlights the potential immunomodulatory effects of phlorotannins from _E. bicyclis_ and _Lactobacillus casei_ on gut microbiota.  
Figure 6: Effects of phlorotannins (TAs) isolated from _E. bicyclis_ and _Lactobacillus casei_ (LC) on mRNA expressions involved in the AhR pathway in DSS-treated mice. (**A**) AhR, (**B**) Nrf2, (**C**) Nsq1, (**D**) II-22, (**E**) Soc3, and (**F**) Stat3 mRNA in colon tissue. \(\beta\)-actin was used as the reference gene. Mice were fed experimental extracts (50 mg/kg bw/day) or PBS via oral gavage for 30 days. Subsequently, from day 17 to day 24, 3% dextran sulfate sodium (DSS) was provided in the drinking water, and _Lactobacillus casei_ (1 \(\times\) 10\({}^{8}\) cells/100 \(\mu\)L) was administered from day 21 to day 28. All data are expressed as mean \(\pm\) SD (\(n\) = 8/group). * \(p\) \(<\) 0.05, ** \(p\) \(<\) 0.01, *** \(p\) \(<\) 0.001, *** \(p\) \(<\) 0.0001. One-way ANOVA followed by Dunnett’s test. DSS: 3% DSS in drinking water for 7 days; DTA: DSS-Phlorotannin; DLC: DSS-_Lactobacillus casei_; DTL: DSS-Phlorotannin-_Lactobacillus casei_.  
Figure 7: Effects of phlorotannins (TAs) isolated from _E. bicyclis_ and _Lactobacillus casei_ (LC) on the gut microbiota distribution in DSS-treated mice. The gut microbiota composition was quantitatively measured using the qPCR results for the selected bacterial group. (**A**) Firmicutes/Bacteroidetes  
ratio, (**B**) _Faecalibacteriumrium prausnitzii_, (**C**) _Akkermansia muciniphila_, (**D**) _Lactobacillus reuteri_, (**E**) _Lactococcus plantarum_, (**F**) _Lactobacillus casei_. The relative abundance of bacterial groups in each fecal sample was expressed as a ratio of total bacteria (F341/R518). Mice were fed experimental extracts (50 mg/kg bw/day) or PBS via oral gavage for 30 days. Subsequently, from day 17 to day 24, 3% dextran sulfate sodium (DSS) was provided in the drinking water, and _Lactobacillus casei_ (1 \(\times\) 10\({}^{8}\) cells/100 \(\mu\)L) was administered from day 21 to day 28. All data are expressed as mean \(\pm\) SD (\(n\) = 8/group). * \(p\) < 0.05, ** \(p\) < 0.01, *** \(p\) < 0.001 non-parametric Kruskal-Wallis test. DSS: 3% DSS in drinking water for 7 days; DTA: DSS-Phlorotannin; DLC: DSS-_Lactobacillus casei_; DTL: DSS-Phlorotannin-_Lactobacillus casei_.