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• IDA

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The intestinal microbiota is a complex microecosystem that participates in the process of nutrient and energy metabolism and is also important for the integrity of the mucosal barrier function.

So far, only a few studies have reported the effects of iron deficiency and iron supplementation on the gut microbiota.
Iron supplementation can reduce the number of enterobacteria in the gut microbiota of iron-deficient rats, and increase the number of enterobacteria in weaned piglets.
In vitro colonic fermentation model experiments for children inoculated with immobilized intestinal microbiota show that iron deficiency will reduce the number of Rossella, Clostridium and Bacteroides, and increase the number of Lactobacillus and Enterobacter, but under high doses of iron The composition and activity of the gut microbiota have no effect.
Therefore, the relationship between the gut microbiota and iron metabolism should be further studied.
In this study, Hong He, Hui Teng, Lei Chen, and Hongbo Song from Fujian Agriculture and Forestry University first studied the therapeutic effect of AOS-iron on IDA-induced cecum, colon tissue damage and intestinal microbiota imbalance, trying to clarify the intestinal microbiota The relationship with IDA biochemical parameters, including blood metabolism parameters, iron content, GSH-PX, T-AOC and MDA levels, and body weight.

Richness and diversity of the gut microbiota

After feeding a low-iron diet for 4 weeks, the number of operational taxonomic units (OTU) and Shannon index of the gut microbiota decreased (Table 1), especially the Shannon index of the anemia model (AM) group and the AOS-iron group Significantly lower than the control (NC) group ( P <0.

Table 1 Statistical analysis of the abundance and diversity of rat intestinal flora

In addition, as shown in Figure 1, principal component analysis (PCA) and principal coordinate analysis (PCoA) are performed to analyze the overall structural changes of the intestinal microbiota.

Figure 1 Diversity analysis of the intestinal flora of different rats

The composition of the gut microbiota

In order to assess the impact of AOS-iron on the composition of the fecal microbiota, the high-throughput sequencing technology based on the Illumina MiSeq platform was used to sequence the V3-V4 regions of the 16S rRNA gene in the fecal samples.
At the phylum level, the relative abundance of different groups of gut microbiota is shown in Figure 2.
Generally speaking, the intestinal microbiota mainly includes 3 levels, among which Firmicutes is the main phylum, followed by Bacteroides and Proteobacteria.
After 4 weeks of iron deficiency, compared with the NC group, the relative abundance of Firmicutes in the AM group decreased, and the relative abundance of Bacteroides and Proteobacteria increased.
However, after 2 weeks of AOS-iron intervention (week 6), compared with the AM group, the relative abundance of Firmicutes in the AOS-iron intervention group increased, and the relative abundance of Proteobacteria decreased, especially in the MD group The relative abundance of Firmicutes and Proteobacteria in the HD group was similar to that of the NC group.
On the other hand, the abundance of actinomycetes, cyanobacteria, soft wall bacteria and fusobacteria did not change significantly.
After AOS-iron intervention for 4 weeks (the 8th week), the characteristics of the intestinal microbiota of the AOS-iron group were similar to those of rats fed the AOS-iron diet for 2 weeks, and the relative abundance of Firmicutes and Proteobacteria was further increased .
Therefore, after 4 weeks of AOS-iron intervention, feeding at low, medium and high doses, the relative abundance of Firmicutes and Proteobacteria returned to near normal levels.

Figure 2 The relative abundance of rat intestinal flora at the gate level at 4th, 6th and 8th weeks

Metagenome analysis at the genus level showed that IDA induced by a low-iron diet changed the composition of the gut microbiota, but AOS-iron intervention suppressed this disadvantage (Figure 3).
At the end of the 6th and 8th week, 65 (Figure 3A) and 67 (Figure 3B) bacteria were identified at the genus level.
These bacteria were significantly affected by iron deficiency or AOS-iron supplementation.
Compared with the group supplemented with AOS-Iron for 2 weeks (week 6), supplementation for 2 weeks (week 8) can significantly promote lactic acid bacteria, faecalis, bifidobacteria, anaerobes, and Anaerostipes The relative abundance of , Butyricimonas , and Rumenococcus , especially in the HD group ( P <0.
05); on the contrary, Bacteroides, Streptococcus, Proteus, Parabacteroides , Morganella , Fusobacterium in the AOS-iron group , Serratia, Sartorella, Gallophilus, and Enterococcus were significantly reduced compared with the AM group ( P <0.
05) (Figure 3).
These results indicate that AOS-iron has a positive effect on the regulation of intestinal microbiota disorders caused by low-iron diets.

A.
Stool samples of rats raised for 6 weeks; B.
Stool samples of rats raised for 8 weeks.

Figure 3 Heat map of genus-level fecal microbiota based on relative abundance

In this study, Spearman correlation analysis was used to study the effects of AOS-iron on the intestinal tissue and microbiota of IDA rats, and to explore the relationship between the intestinal microbiota and iron metabolism disorders.
After supplementing AOS-iron for 4 weeks, medium and high doses of AOS-iron can effectively repair the lesions of the cecum and colon tissue.
Low-dose AOS-iron can increase the diversity of the gut microbiota to baseline, enrich the beneficial microbiota and reduce potential opportunistic pathogens.
Spearman correlation analysis showed that biochemical parameters, MDA content expectations and SMB53, anaerobic rod-like species, Anaerostipes positively correlated with dung and Bacillus spp, but Morgan spp, Fusobacterium and Serratia negative correlation.
The improvement of the intestinal microbiota restores iron metabolism disorders to normal levels.
In conclusion, this study shows that AOS-iron confers additional health benefits to the host by stimulating the gut microbiota.

Beneficial effects of AOS-iron supplementation on intestinal structure and microbiota in IDA rats

Hong He ^a,1 , Hui Teng ^a,1 , Qun Huang ^a,b , Dan He ^a , Fengping An ^a,b , Lei Chen ^a,* , Hongbo Song ^a,b,*

^a College of Food Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China

^b Fujian Provincial Key Laboratory of Quality Science and Processing Technology in Special Starch, Fuzhou 350002, China

¹ Authors contributed equally to this work.

*Corresponding authors.

chenlei841114@hotmail.
com

sghgbode@163.

Abstract

The objective of this study was to investigate the effects of agar oligosaccharide-iron (AOS-iron) on intestinal tissue pathology and microbiota in IDA rats induced by a low-iron diet, further to find the relationship between intestinal microbiota and iron metabolic disorders.