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Journal of Fish Diseases - 2023 - Amin - Screening and activity of potential gastrointestinal probiotic lactic acid.pdf (3.56 MB)

Screening and activity of potential gastrointestinal probiotic lactic acid bacteria against Yersinia ruckeri O1b

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journal contribution
posted on 2023-05-21, 16:40 authored by Amin, M, Mark AdamsMark Adams, Burke, CM, Christopher BolchChristopher Bolch

Yersiniosis of cultured Atlantic salmon is a recurrent fish health management challenge in many continents. The causative organism, Yersinia ruckeri, can reside latently in the gut and lead to acute infection and disease during hatchery and sea-transfer stages. One potential prevention approach is the administration of probiotic bacteria to suppress gut colonization of Y. ruckeri. Our study aimed to isolate and identify anti-Yersinia activity among lactic acid bacteria (LAB) isolated from the gastrointestinal tract (GIT) of aquatic animals. Of the 186 aquatic GIT isolates examined, three strains showed diffusible antimicrobial activity towards Y. ruckeri O1b. Analysis of 16 s rRNA gene sequences indicated the three bacterial strains were Enterococci, related to Enterococcus sp. (99%), Enterococcus thailandicus (99%), and Enterococcus durans (99%). Anti-Yersinia activity was maintained at neutral pH (~6.5–7.0), and in-vitro environmental tolerance assays showed the three strains could withstand simulated salmonids gastrointestinal tract conditions of: low pH (3.4) and 3% bile salt content. All three Enterococci strains showed higher adhesion to the intestinal mucus of Atlantic salmon than Y. ruckeri O1b (E. durans 24%, E. enterococcus sp. 25% and E. thailandicus 98%, compared to Y. ruckeri O1b 5%). However, only Enterococcus sp. and E. thailandicus were able to grow in the salmon intestinal mucus broth while E. durans showed no growth. Anti-Yersinia activity was completely inactivated by proteinase-K treatment, suggesting that the active compound/s are proteinaceous and may be bacteriocin-like inhibitory substances (BLIS). Our data indicate that Enterococcus sp. MA176 and E. thailandicus MA122 are potential probionts for the prevention of yersiniosis in salmonids. Further in-vivo studies are required to determine whether these bacteria reduce the incidence of yersiniosis in Atlantic salmon.


Publication title

Journal of Fish Diseases










Institute for Marine and Antarctic Studies


Blackwell Publishing Ltd

Place of publication

9600 Garsington Rd, Oxford, England, Oxon, Ox4 2Dg

Rights statement

Copyright (2023) The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License (, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Repository Status

  • Open

Socio-economic Objectives

Aquaculture fin fish (excl. tuna)

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