Bacillus subtilis H2 modulates immune response, fat metabolism and bacterial flora in the gut of grass carp (Ctenopharyngodon idellus)

Fei Shi; Yingjuan Zi; Zhijie Lu; Fenglin Li; Minxuan Yang; Fanbin Zhan; Yanan Li; Jun Li; Lijuan Zhao; Li Lin; Zhendong Qin

doi:10.1016/j.fsi.2020.06.061

Bacillus subtilis H2 modulates immune response, fat metabolism and bacterial flora in the gut of grass carp (Ctenopharyngodon idellus)

Fish Shellfish Immunol. 2020 Nov:106:8-20. doi: 10.1016/j.fsi.2020.06.061. Epub 2020 Jul 25.

Authors

Fei Shi¹, Yingjuan Zi¹, Zhijie Lu¹, Fenglin Li¹, Minxuan Yang¹, Fanbin Zhan¹, Yanan Li¹, Jun Li², Lijuan Zhao¹, Li Lin³, Zhendong Qin⁴

Affiliations

¹ Guangdong Provincial Water Environment and Aquatic Products Security Engineering Technology Research Center, Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, College of Animal Sciences and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, Guangdong, 510225, China.
² Guangdong Provincial Water Environment and Aquatic Products Security Engineering Technology Research Center, Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, College of Animal Sciences and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, Guangdong, 510225, China; School of Biological Sciences, Lake Superior State University, Sault Ste. Marie, MI, 49783, USA.
³ Guangdong Provincial Water Environment and Aquatic Products Security Engineering Technology Research Center, Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, College of Animal Sciences and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, Guangdong, 510225, China. Electronic address: linli@zhku.edu.cn.
⁴ Guangdong Provincial Water Environment and Aquatic Products Security Engineering Technology Research Center, Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, College of Animal Sciences and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, Guangdong, 510225, China. Electronic address: qinzhendongsc@163.com.

PMID: 32717323
DOI: 10.1016/j.fsi.2020.06.061

Abstract

Functional ingredients such as Bacillus subtilis are used in aquaculture to improve fish condition, modulate microbiota and promote a healthy intestinal system. However, the underlying mechanisms of grass carp treated with B. subtilis are not fully characterized. This study investigated the gut microbes of grass carp after treated with B. subtilis H2 (10⁶ CFU/mL) and Aeromonas hydrophila (10⁶ CFU/mL). The intestinal flora was found that the dominant bacterial phyla identified in all samples were Proteobacteria, Actinobacteria, Fusobacteria, Bacteroidetes and Acidobacteria. Compared with the control group, the relative abundance of Proteobacteria and Bacteroidetes in B. subtilis group were significantly increased. In addition, the relative abundances of Aeromonas and Shewanella in A. hydrophila group were more than the control group. For the intestinal transcriptomic profiling of the grass carp treated with B. subtilis H2, 824 different expressed genes (DEGs) between the B. subtilis H2 treated and non-treated groups were detected, including 365 up-regulated and 459 down-regulated genes. Six DEGs were randomly selected for further validation by quantitative real-time RT-PCR (qRT-PCR) and the results were consistent with the RNA-seq data. Additionally, eight immunomodulatory genes (IL-4, IL-11, IFN-α, CSF, FOSB, MAPK12b, IGHV3-11 and IGHV3-21) were significantly up-regulated after treated with B. subtilis H2. Furthermore, almost all the lipid metabolism-associated genes were significantly up-regulated after treated with B. subtilis H2 according to the lipid metabolism pathways. Eleven lipid metabolism-associated genes were selected by qRT-PCR, which showed that the expressions of almost all the selected genes were increased, especially Apob-48, ABCG8 and DGAT. Taken together, our results support that B. subtilis could modulate the immune response, fat metabolism and bacterial assembly in the gut of grass carp.

Keywords: Bacillus subtilis H2; Fat digestion and absorption; Grass carp; Gut microbes; Transcriptome.

MeSH terms

Aeromonas hydrophila / physiology
Animal Feed / analysis
Animals
Bacillus subtilis / chemistry*
Bacteria / isolation & purification
Carps / immunology*
DNA, Bacterial / analysis
Diet / veterinary
Dietary Supplements / analysis
Dose-Response Relationship, Drug
Fish Diseases / genetics
Fish Diseases / immunology*
Fish Proteins / genetics*
Fish Proteins / immunology
Gastrointestinal Microbiome
Gene Expression Profiling / veterinary
Gene Expression Regulation / immunology*
Gram-Negative Bacterial Infections / immunology
Gram-Negative Bacterial Infections / veterinary
Immunity, Innate / genetics*
Lipid Metabolism*
Probiotics / administration & dosage
Probiotics / metabolism
RNA, Ribosomal, 16S / analysis
RNA-Seq / veterinary
Random Allocation

Substances

DNA, Bacterial
Fish Proteins
RNA, Ribosomal, 16S