Effect of mannan oligosaccharides on the microbiota and productivity parameters of Litopenaeus vannamei shrimp under intensive cultivation in Ecuador

Oreste Gainza,Jaime Romero

doi:10.1038/s41598-020-59587-y

Abstract

The white leg Litopenaeus vannamei shrimp is of importance to the eastern Pacific fisheries and aquaculture industry but suffer from diseases such as the recently emerged early mortality syndrome. Many bacterial pathogens have been identified but the L. vannamei microbiota is still poorly known. Using a next-generation sequencing (NGS) approach, this work evaluated the impact of the inclusion in the diet of mannan oligosaccharide, (MOS, 0.5% w/w), over the L. vannamei microbiota and production behavior of L. vannamei under intensive cultivation in Ecuador. The MOS supplementation lasted for 60 days, after which the shrimp in the ponds were harvested, and the production data were collected. MOS improved productivity outcomes by increasing shrimp survival by 30%. NGS revealed quantitative differences in the shrimp microbiota between MOS and control conditions. In the treatment with inclusion of dietary MOS, the predominant phylum was Actinobacteria (28%); while the control group was dominated by the phylum Proteobacteria (30%). MOS has also been linked to an increased prevalence of Lactococcus- and Verrucomicrobiaceae-like bacteria. Furthermore, under the treatment of MOS, the prevalence of potential opportunistic pathogens, like Vibrio, Aeromonas, Bergeyella and Shewanella, was negligible. This may be attributable to MOS blocking the adhesion of pathogens to the surfaces of the host tissues. Together, these findings point to the fact that the performance (survival) improvements of the dietary MOS may be linked to the impact on the microbiota, since bacterial lines with pathogenic potential towards shrimps were excluded in the gut.

Highlights

The “white leg” Litopenaeus vannamei shrimp is originally from waters of the equatorial Pacific east coast
These supplements may be (i) probiotics, defined by Merrifield et al.[28] as any microorganism supplied through the feed or culture water that benefits the host; (ii) prebiotics, defined by Bindels et al.[29] as an indigestible compound which, via its metabolic breakdown by microorganisms in the intestine, acts on the profile and functionality of the intestinal microbiota, giving it a positive action on the host as an improvement of food growth and efficiency; or iii) symbiotic, which are defined by Gibson & Roberfroid (1995)[30] as nutritional supplements containing a prebiotic and a probiotic that beneficially influence the host by acting on the survival and implantation of live microorganisms as dietary supplements in the gastrointestinal tract
This action was coordinated with the new moon phase because this was the period during which the largest proportion of the shrimp was in Stage C of the molting cycle[49]

Summary

Introduction

The “white leg” Litopenaeus vannamei shrimp is originally from waters of the equatorial Pacific east coast. Bacterial strains derived from intestinal microbiota such as Pediococcus acidilactici[21,22,23] and Bacillus subtilis[24,25,26] have been tested in various aquaculture species and shown beneficial effects Thes.e advances have fostered a growing interest in microbiota modulation and their consequences on the productivity performance of animals under cultivation[9,10,27] These supplements may be (i) probiotics, defined by Merrifield et al.[28] as any microorganism supplied through the feed or culture water that benefits the host; (ii) prebiotics, defined by Bindels et al.[29] as an indigestible compound which, via its metabolic breakdown by microorganisms in the intestine, acts on the profile and functionality of the intestinal microbiota, giving it a positive action on the host as an improvement of food growth and efficiency; or iii) symbiotic, which are defined by Gibson & Roberfroid (1995)[30] as nutritional supplements containing a prebiotic and a probiotic that beneficially influence the host by acting on the survival and implantation of live microorganisms as dietary supplements in the gastrointestinal tract. These observations have not been validated at a commercial farming scale, limiting the application of those prebiotics

Methods

Results

Conclusion