Publication:
Isolation of Lactic Acid Bacteria (LAB) from salmonids for potential use as probiotics: in vitro assays and toxicity assessment of salmo trutta embryonated eggs

Date

2024

Director

Publisher

MDPI
Acceso abierto / Sarbide irekia
Artículo / Artikulua
Versión publicada / Argitaratu den bertsioa

Project identifier

European Commission/Horizon 2020 Framework Programme/801586openaire

Abstract

This research investigates the potential of lactic acid bacteria (LAB) from freshwater salmonids as prospective probiotics for application in aquaculture. LAB and pathogenic bacteria were obtained from mucus and tissues of Oncorhynchus mykiss and Salmo trutta from fish farms in northeast Spain that had not used antibiotics for the six months preceding the study. Isolates were identified using Gram staining and sequencing of 16S rRNA and ITS-1. To assess the safety of the LAB, antibiotic susceptibility tests (ASTs) against 23 antimicrobials were performed. In vitro antagonism assays were conducted to evaluate the inhibitory effects of living LAB using the agar diffusion test method and their metabolites using the agar well diffusion method. The assays targeted six specific pathogens: Aeromonas salmonicida subsp. salmonicida, Carnobacterium maltaromaticum, Vagococcus salmoninarum, Yersinia ruckeri, Lactococcus garvieae, and the marine pathogen Vibrio jasicida. Additionally, a toxicity assay was conducted on embryonic eggs of S. trutta. The ASTs on probiotic LAB candidates revealed varied responses to antimicrobials, but no resistance to oxytetracycline or florfenicol, which are two antibiotics commonly used in aquaculture, was detected. The in vitro assays indicate that LAB exhibit antagonistic effects against pathogens, primarily when directly stimulated by their presence. In applications involving embryonic eggs or larvae, certain live strains of LAB were found to have adverse effects, with some isolates resulting in higher mortality rates compared to the control group or other isolates. Furthermore, the potential pathogenicity of certain LAB strains, typically considered safe in salmonids, warrants deeper investigation.

Description

Keywords

Antagonistic assays, Antimicrobial resistance, Embryonated eggs, Fish pathogens, Lactic acid bacteria, Probiotics, Salmo trutta, Salmonids

Department

Ciencias de la Salud / Osasun Zientziak

Faculty/School

Degree

Doctorate program

item.page.cita

Vargas-González, A., Barajas, M., Pérez-Sánchez, T. (2024) Isolation of Lactic Acid Bacteria (LAB) from salmonids for potential use as probiotics: in vitro assays and toxicity assessment of salmo trutta embryonated eggs. Animals, 14(2), 1-23. https://doi.org/10.3390/ani14020200.

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© 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.

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