Effect of Bacillus megaterium-Coated Diets on the Growth, Digestive Enzyme Activity, and Intestinal Microbial Diversity of Songpu Mirror Carp Cyprinus specularis Songpu.

Liang Luo,Qiyou Xu,Zhigang Zhao,Wei Xu,Jinnan Li,Liansheng Wang,Chang’An Wang,María De Guía Córdoba

doi:10.1155/2020/8863737

Liang Luo, Qiyou Xu + Show 6 more

Open Access

https://doi.org/10.1155/2020/8863737

Copy DOI

Abstract

The present study was conducted to evaluate the effect of a Bacillus megaterium-coated diet on growth performance, digestive enzymes, and intestinal microbial diversity in Songpu mirror carp (Cyprinus specularis Songpu). The fish were manually fed two diets (a control diet and a B. megaterium-coated diet) three times daily until apparent satiation for 56 days. Compared with the control group, supplementation with the B. megaterium-coated diet enhanced the fish growth and significantly reduced the feed conversion ratio (P < 0.05). The activities of foregut amylase and lipase in the treatment group were significantly higher than those in the control group (P < 0.05). The activities of foregut, midgut, and hindgut proteases in the treatment group were all higher than those in the control group (P > 0.05). The results of sequencing the 16S rDNA genes of the microbiota through high-throughput sequencing showed that the diversity and abundance of the intestinal microflora increased along with Songpu mirror carp growth. The Songpu mirror carp fed a diet coated with B. megaterium displayed increased proportions of intestinal Bacillus and Lactococcus at the genus level, and both were significantly higher than those of the control group (P < 0.05). These results therefore suggest that dietary B. megaterium application can improve the growth and digestive enzyme activity of Songpu mirror carp and enrich the beneficial genus composition of its main intestinal microflora.

Highlights

Fish, as one of the main dietary sources of animal protein, play a very important role in the human food structure
We aimed to evaluate the effect of B. megateriumcoated diets on the growth, digestive enzyme activity, and intestinal microbial diversity in Songpu mirror carp and to provide a theoretical basis for the practice of healthy and ecological fish farming
Manipulation of microbiota using probiotics has been reported as a worthy practice for aquaculture to control or inhibit pathogenic bacteria and to improve growth performance and the activity of digestive enzymes [27]

Summary

Introduction

As one of the main dietary sources of animal protein, play a very important role in the human food structure. With the rapid development of high-density intensive farming, the aquaculture water environment is deteriorating daily, resulting in disease outbreaks and even mass deaths of farmed animals. Studies have shown that the use of probiotics can promote the growth of aquatic animals and improve their survival rate and can reduce the incidence of aquatic animal diseases [6, 7]. The first application of probiotics in aquaculture was carried out by balancing the bacterial population in the water, and it achieved good results [9]. Some studies have shown that adding Bacillus subtilis to feed can promote the growth of aquatic animals and improve the activities of their digestive enzymes and their nonspecific immunity and can improve the structure of their intestinal microflora [10,11,12]. In the middle of the 20th century, Chinese scholars began to study Bacillus megaterium, mainly focusing on screening

Objectives

Methods

Results

Conclusion