Feed Supplementation with a Commercially Available Probiotic Solution Does Not Alter the Composition of the Microbiome in the Biofilters of Recirculating Aquaculture Systems.

Mansour El-Matbouli,Rui A. Gonçalves,Simon Menanteau-Ledouble

doi:10.3390/pathogens9100830

Mansour El-Matbouli, Rui A. Gonçalves + Show 1 more

Open Access

https://doi.org/10.3390/pathogens9100830

Copy DOI

Abstract

Recirculating aquaculture relies on the treatment of ammonia compounds from the water by a bacterial flora growing inside biofilters. Another increasingly common practice in aquaculture is the supplementation of feed with live probiotic bacteria to boost the immune system of the farmed animals and hinder the implantation of pathogenic bacteria. In the present study, we investigated the bacterial flora within the biofilters of recirculating farming units in which African catfish (Clarias gariepinus) were being farmed. Our results suggested that these two farming systems could be compatible as feeding of the probiotic feed had no detectable effect on the composition of the microbiome within the biofilters and none of the bacteria from the feed could be detected in the biofilters. These findings suggest that supplementation of the fish feed with probiotic supplements did not interfere with the microbiome residing inside the biofilter and that it is a safe practice in recirculating aquaculture systems.

Highlights

Aquaculture has been the fastest growing animal food-producing sector for several decades and production from aquaculture is expected to almost double in the decade [1,2]
The total read count for each amplicon was further used to estimate the relative prevalence of each bacterial genus and these were compared between treatments and time points
A large number of different bacteria were identified in all samples, suggesting that the microbiome in the filters was diverse rather than dominated by a small numbers of bacterial species

Summary

Introduction

Aquaculture has been the fastest growing animal food-producing sector for several decades and production from aquaculture is expected to almost double in the decade [1,2]. The industry is still hindered by the occurrence of infectious diseases [3,4], especially considering that outbreaks of bacterial diseases are still largely treated through the application of antibiotics, which has become an urgent public health issue in the face of rising antibiotic resistance [5] Both the application of probiotics and cultivation in recirculating aquaculture systems (RAS) have been growing trends for the aquaculture industry over the last decades. These nitrifying bacteria are often seeded to the biofilter, for example by including biofilter media from a previously established biofilter, placing a small number of fish inside the system has been performed [15] This method can be dangerous for the animals as the filter is not yet ready to remove nitrogenous compounds and their levels will rise rapidly in the RAS. Because of the central role of the biofilter units in RAS, it is important to confirm that probiotic supplementation does not interfere with their native microbiome or function

Materials and Methods

Sample Collection

Results and Discussion