Metagenomic characterization of the cecal microbiota community and functions in finishing pigs fed fermented Boehmeria nivea

Xiaoxiao Liang; Zhenya Zhai; Fengyun Ren; Yucheng Jie; Soo-Ki Kim; Kai-Min Niu; Xin Wu

doi:10.3389/fvets.2023.1253778

Metagenomic characterization of the cecal microbiota community and functions in finishing pigs fed fermented Boehmeria nivea

Front Vet Sci. 2023 Sep 28:10:1253778. doi: 10.3389/fvets.2023.1253778. eCollection 2023.

Authors

Xiaoxiao Liang¹, Zhenya Zhai^{2

3}, Fengyun Ren⁴, Yucheng Jie⁴, Soo-Ki Kim⁵, Kai-Min Niu^{2

3}, Xin Wu^{2

3

6}

Affiliations

¹ College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, China.
² Jiangxi Functional Feed Additive Engineering Laboratory, Institute of Biological Resource, Jiangxi Academy of Sciences, Nanchang, China.
³ CAS Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Changsha, China.
⁴ College of Animal Science and Technology, Hunan Agricultural University, Changsha, China.
⁵ Department of Animal Science and Technology, Konkuk University, Seoul, Republic of Korea.
⁶ Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China.

Abstract

Ramie (Boehmeria nivea, BN) is used as livestock forage through suitable silage fermentation owing to its nutritional value. To date, relatively few studies have investigated the effects of dietary fermented BN (FBN) on gut health in finishing pigs. The aim of the present study was to investigate the effects of dietary supplementation with 20% FBN on intestinal morphology, gene expression, and the functional response of the gut microbiota in finishing pigs. We found that FBN did not significantly affect serum antioxidant enzyme activities, ileal morphology, or the expression of genes encoding antioxidant enzymes, inflammatory cytokines, or tight junction proteins in the liver of the pigs. However, the gene expression levels of aryl hydrocarbon receptor (AHR) and interleukin 6 (IL6) were significantly downregulated in the ileum. A metagenomic analysis demonstrated that, compared with that seen in the control group, the cecal microbiota of pigs in the FBN treatment group was more closely clustered and contained a greater number of unique microbes. Bacteria were the predominant kingdom in the cecal microbiota, while Firmicutes, Bacteroidetes, and Proteobacteria were the dominant phyla, and Streptococcus, Lactobacillus, and Prevotella were the dominant genera. Dietary FBN significantly increased the abundance of the probiotic bacterium Roseburia inulinivorans (p < 0.05). Functional analysis of the cecal microbiota showed that ABC transporter levels and glycolysis/gluconeogenesis-associated functions were diminished in FBN-fed pigs. Meanwhile, CAZyme analysis revealed that dietary FBN significantly downregulated the contents of carbohydrate-active enzymes, such as GT2, GH1, GH25, and GH13_31. In addition, cytochrome P450 analysis revealed that the abundance of CYP51 and CYP512 decreased with FBN treatment. An assessment of antibiotic resistance based on the Comprehensive Antibiotic Resistance Database (CARD) annotation indicated that the cecal microbes from pigs in the FBN treatment group had increased resistance to lincosamide, streptogramin, and chloramphenicol and reduced resistance to amikacin, isepamicin, neomycin, lividomycin, gentamicin, paromomycin, ribostamycin, and butirosin. Finally, virulence factor-related analysis showed that putative hemolysin-associated functions were decreased, whereas fibronectin-binding protein, flagella, and alginate-associated functions were increased. Taken together, our data showed that FBN supplementation exerted only minor effects on intestinal morphology and microbial community composition, suggesting that it is potentially safe for use as a supplement in the diets of finishing pigs. However, more studies are needed to validate its functionality.

Keywords: Boehmeria nivea; cecal microbiota; fermentation; metagenomics; pigs.

Grants and funding

This work was financially supported by the pilot demonstration project for the Overall Rationing System of the Jiangxi Academy of Sciences (Grant Nos. 2022YSBG22002 and 2022YJC2002), the cooperation project of the Chinese Academy of Sciences and local governments (Grant No. 2022-03JXZT-02), the Key Collaborative Research Program of the Alliance of International Science Organizations (Grant No. ANSO-CR-KP-2021-10), and the Central Government Guides Local Science and Technology Development Fund of China (Grant No. 20231zdf03076).