Effects of Zn-Enriched Bifidobacterium longum on the Growth and Reproduction of Rats

Abstract

Zn is an essential trace element required for maintaining normal growth and development. Zn deficiency can cause growth retardation and reproductive system dysplasia, while Zn supplementation for treating Zn deficiency requires the use of high-quality Zn preparations. In this study, Bifidobacterium longum CCFM1195 was screened for its high Zn enrichment capacity, and the effects of different Zn supplementation regimens and doses on the growth and development of rats after Zn supplementation were investigated by supplementing Zn-deficient rat pups with different doses of various Zn supplements (ZnO, CCFM1195 + ZnO, and Zn-enriched CCFM1195). It was shown that the bioavailability of Zn was positively correlated with indicators of recovery after Zn supplementation, with Zn-enriched CCFM1195 having the best effect, followed by CCFM1195 + ZnO, while ZnO had the worst effect. Significant differences were also observed between the gut microbiota of control, model, and Zn-supplemented rats. Overall, administration of Zn-enriched CCFM1195 was more effective than the other approaches in restoring physical indicators of Zn deficiency after Zn supplementation, and this advantage was more significant at low-dose Zn supplementation.

Keywords: Zn; Zn-enriched Bifidobacterium longum; growth and reproduction development; gut microbiota.

Figure 1

Ability of different strains to enrich Zn in the medium with an initial Zn concentration of 200 mg/L. Data are presented as mean ± SEM (n = 5).

Figure 2

Effects of Zn supplementation on apparent characteristics of growth and reproduction. (A) Rat weight on the last day of gavage. (B) Testis weight of rats. Data are presented as mean ± SEM (n = 5). Different letters indicate significant differences (p < 0.05) based on Duncan’s test. (C) Photos of rats. From left to right: one rat each from control, model, ZnO, CCFM1195 + ZnO, and Zn-enriched CCFM1195 groups. Medium doses were employed in the case of all Zn treatment groups included.

Figure 3

Effects of Zn supplementation on the Zn content in different tissues. (A) Zn content in serum, an indicator of Zn absorption. (B) Zn content in the liver, an indicator of Zn utilization. (C) Zn levels in the testes, indicative of the use of Zn by the testes. Data are presented as mean ± SEM (n = 5). Different letters indicate significant differences (p < 0.05) based on Duncan’s test.

Figure 4

Activities of alkaline phosphatase (ALP) in serum. Different letters indicate significant differences (p < 0.05) based on Duncan’s test.

Figure 5

Effects of Zn supplementation on the growth hormone and testosterone concentrations in serum. (A) Growth hormone concentration. (B) Testosterone concentration. Data are presented as mean ± SEM (n = 5). Different letters indicate significant differences (p < 0.05) based on Duncan’s test.

Figure 6

Effects of Zn supplementation on the Zn content in the intestinal tract. (A–C) Zn contents in the ileum, cecum, and colon, respectively, representing the Zn absorbed. (D) Zn content in feces, representing the Zn excreted in the stool. Data are presented as mean ± SEM (n = 5). Different letters indicate significant differences (p < 0.05) based on Duncan’s test.

Figure 7

Pharmacokinetic analysis of adult SD rats. Data are presented as mean ± SEM (n = 5).

Figure 8

Alpha diversity, beta diversity, and LEfSe analysis. (A) Alpha diversity of bacterial communities in different treatment groups. The total number of microbial species in samples is represented by Chao1 indices, observed species, and Good’s coverage. Different letters indicate significant differences (p < 0.05) based on Duncan’s test. (B) Principal coordinates analysis (PCoA) results of each sample. (C) Linear Discriminant Analysis Effect Size (LEfSe) analysis identified the most differentially abundant taxon between each group. The evolutionary branch diagram depicts the taxonomic phylum, class, order, family, genus, and species from center to periphery. At each categorization level, each node represents a species. Species with no notable differences are indicated by yellow nodes. (D) Species with an LDA score > 3. (E) P values of relative abundances of the microbiota markers at the genus level in the different groups. The p values were calculated by comparison with the model group. (F) Composition of the sample of intestinal bacteria at discrepant genus, expressed in relative abundance.

Figure 8

Alpha diversity, beta diversity, and LEfSe analysis. (A) Alpha diversity of bacterial communities in different treatment groups. The total number of microbial species in samples is represented by Chao1 indices, observed species, and Good’s coverage. Different letters indicate significant differences (p < 0.05) based on Duncan’s test. (B) Principal coordinates analysis (PCoA) results of each sample. (C) Linear Discriminant Analysis Effect Size (LEfSe) analysis identified the most differentially abundant taxon between each group. The evolutionary branch diagram depicts the taxonomic phylum, class, order, family, genus, and species from center to periphery. At each categorization level, each node represents a species. Species with no notable differences are indicated by yellow nodes. (D) Species with an LDA score > 3. (E) P values of relative abundances of the microbiota markers at the genus level in the different groups. The p values were calculated by comparison with the model group. (F) Composition of the sample of intestinal bacteria at discrepant genus, expressed in relative abundance.