scholarly journals Effects of Dietary Enterococcus faecalis YFI-G720 on the Growth, Immunity, Serum Biochemical, Intestinal Morphology, Intestinal Microbiota, and Disease Resistance of Crucian Carp (Carassius auratus)

Fishes ◽  
2022 ◽  
Vol 7 (1) ◽  
pp. 18
Author(s):  
Yan Xu ◽  
Yiqun Li ◽  
Mingyang Xue ◽  
Zidong Xiao ◽  
Yuding Fan ◽  
...  

Diseases of crucian carp (Carassius auratus) are closely related to intestinal parameters. Enterococcus faecalis has strong colonization ability in the intestinal tract, and produces natural antibiotics, bacteriocin, and other bacteriostatic substances, which can effectively inhibit some pathogenic bacteria and improve the intestinal microenvironment. This study aimed to assess the effects of E. faecalis YFI-G720 which was isolated from the intestinal of crucian carp on the growth, immunity, intestinal health, and disease resistance of crucian carp. Fish (48.16 ± 0.55 g) were fed four diets, commercial diet or diet containing E. faecalis at 105 CFU/g (EF1), 106 CFU/g (EF2), or 107 CFU/g (EF3) for 28 days. The results showed that supplementation of E. faecalis significantly improved the weight gain ratio (WGR) and the specific growth rate (SGR) compared with control group (p < 0.05). Intestinal mucosal epithelial cells in EF2 were intact and normal, but there was obvious vacuolation in CG. Compared with CG, serum C3 and IgM in EF2 were significantly increased at the end of the experiment (p < 0.05), and serum alkaline phosphatase was significantly higher in all experimental groups (p < 0.05). Among studied immune-related genes, expression was detected by qPCR, C3, IgM, and IL-1βwere upregulated in all experimental groups to varying degrees from 14 days, with highest expression in EF2 at 28 days. Intestinal microbiota structure analyzed through high-throughput sequencing, and the results showed that the relative abundance of Aeromonas and Acinetobacter decreased while Cetobacterium increased in all experimental groups, with the greatest changes in EF2. Challenge tests showed that fish fed E. faecalis were more resistant to Aeromonas veronii (p < 0.05). In conclusion, dietary E. faecalis YFI-G720 at 106 CFU/g can improve the health status, immune parameters, intestinal microbiota composition, and disease resistance of crucian carp.

Animals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1963
Author(s):  
Yan Xu ◽  
Yiqun Li ◽  
Mingyang Xue ◽  
Tao Yang ◽  
Xiaowen Luo ◽  
...  

The present study aimed to evaluate the effect of the dietary supplementation of Saccharomyces cerevisiae YFI-SC2 on the growth performance, intestinal morphology, immune parameters, intestinal microbiota, and disease resistance of crayfish (Procambarus clarkia). Crayfish were randomly assigned to six different boxes and two different groups in triplicate. The control group received a basal diet and the treatment group received a diet containing S. cerevisiae at 107 CFU/g. After feeding for 28 days, crayfish of the treatment group exhibited a significantly better weight gain ratio (WGR) and a specific growth rate (SGR) (p < 0.05) than crayfish of the control group. Compared to the treatment group, the control group intestines showed an oedema connective tissue layer and a weak muscle layer. For immune-related genes, Crustin2 expression was similar between the groups, whereas Lysozyme and prophenoloxidase from treatment group expression levels were upregulated significantly (p < 0.05) after 14 and 28 days of feeding. Prophenoloxidase showed the highest expression, with 10.5- and 8.2-fold higher expression than in the control group at 14 and 28 days, respectively. The intestinal microbiota community structure was markedly different between the two groups. After 14 and 28 days of feeding, the relative abundance of Cetobacterium and Lactobacillus increased, whereas Citrobacter and Bacteroides decreased in the treatment group compared with that of the control group. The challenge test showed that crayfish of the treatment group had a significantly enhanced resistance against Citrobacter freundii (p < 0.05). Our results suggest that a S. cerevisiae-containing diet positively influenced the health status, immune parameters, intestinal microbiota composition, and disease resistance of crayfish.


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