In vitro Selection of Synbiotics and in vivo Investigation of Growth Indices, Reproduction Performance, Survival, and Ovarian Cyp19α Gene Expression in Zebrafish Danio rerio.

Hamideh Zakariaee,Seyede Sedighe Hosseini,Kartik Baruah,Hamed Paknejad,Mohammad Sudagar

doi:10.3389/fmicb.2021.758758

Abstract

In this study, we tested the compatibility of two extracts from the plant Jerusalem artichokes and button mushrooms with two different Lactobacillus probiotics (Lactobacillus acidophilus; La and Lactobacillus delbrueckii subsp. Bulgaricus; Lb) to develop a synbiotic formulation to improve the growth, survival, and reproductive performances of farmed fishes. Initially, we employed in vitro approach to monitor the growth of the probiotic lactobacilli in the presence of the different doses of the plant-based prebiotics, with the aim of selecting interesting combination(s) for further verification under in vivo conditions using zebrafish as a model. Results from the in vitro screening assay in the broth showed that both the probiotic species showed a preference for 50% mushroom extract as a source of prebiotic. A synbiotic formulation, developed with the selected combination of L. acidophilus, L. bulgaricus, and 50% mushroom extract, showed a positive influence on the growth and reproductive performances of the zebrafish. Our findings also imply that the improvement in the reproductive indices was associated with the upregulation of a cyp19a gene. Overall results suggest that a combination of L. acidophilus, L. bulgaricus, and mushroom extract can be considered as a potential synbiotic for the successful production of aquaculture species.

Highlights

The gut microbiota plays a central role in the health, well-being, growth, and disease prevention in fish (Xiong et al, 2019)
We tested the compatibility of two extracts from the plant Jerusalem artichokes and button mushrooms with two different Lactobacillus probiotics to develop a synbiotic formulation with the aim to improve the growth and reproductive performances of farmed fishes
Our results showed that when the two probiotic strains were tested in the presence of the two different plant extracts, a clear increase in the growth rate was achieved by both the strains, the growth promotion effect of the plant extracts on the tested probiotic strains was dose-dependent

Summary

Introduction

The gut microbiota plays a central role in the health, well-being, growth, and disease prevention in fish (Xiong et al, 2019). Despite all the health benefits of probiotics, a major limitation that remains for their uses as gut/health beneficial agents in farmed fish is related to the poor capacity of the administered probiotic strains to stably or even transiently colonize the host gastrointestinal mucosal surface (Suez et al, 2019; Amenyogbe et al, 2020) To overcome these limitations of probiotics, prebiotics are used together with probiotics to have a synergistic effect (an approach referred to as synbiotics) to markedly inhibit the growth of pathogenic microbes and improve the growth and/or activity of the beneficial/ probiotic microorganisms in the host gut (FAO, 2007). There is evidence to suggest that synbiotics influence the microbial ecology of the intestines of fish and play a role in causing beneficial effects on the health and growth traits of farmed fish, e.g., by preventing the negative effects imposed by infection as well as environmental stress, and by elevating the activities of the digestive enzymes, which eventually contribute to improved feed utilization and growth performances (Huynh et al, 2017; Kumar et al, 2018; Mohammadian et al, 2019; Hasyimi et al, 2020; Moustafa et al, 2020; Kong et al, 2021)

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Conclusion