Control of Edwardsiella tarda infection in turbot Scophthalmus maximus (L.) using phage vB_EtaM_ET‐ABTNL‐9

Abstract

In recent years, turbot (Scophthalmus maximus L.) ascites caused by Edwardsiella tarda has occurred frequently in China, causing serious economic losses. In this study, with E. tarda ET9 as the host bacteria, a lytic phage was isolated and named vB_EtaM_ET-ABTNL-9 (referred to as PETp9). The effect of using phage to prevent and control E. tarda infection in turbot was discussed. The results showed that the best preventive effect was achieved after 7 days of feeding phage with multiplicity of infection (MOI) = 10 in the phage-feeding experiment; in the phage-injection therapy, treatment was most effective when the phage with MOI = 10 was injected intraperitoneally immediately after the challenge; in the phage-immersion therapy, the best therapeutic effect was obtained when the infected turbot were immersed in phage-seawater mixture (MOI = 10) for 3 h. During the experimental period, the activities of non-specific immune-related enzymes in the blood of turbot were significantly increased in the untreated group, while that of the phage treated group showed a downward trend and gradually reached normal levels. It was also observed that a certain concentration of phages was present in both turbot cultured water and the intestinal tract during the experiment. Therefore, phage may be another effective control agent against E. tarda infection in turbot culture.

Antimicrobial Activity, Genetic Relatedness, and Safety Assessment of Potential Probiotic Lactic Acid Bacteria Isolated from a Rearing Tank of Rotifers (Brachionus plicatilis) Used as Live Feed in Fish Larviculture

“…This strain-specific antimicrobial sensitiveness has been previously reported for different antimicrobial mechanisms, such as copper and silver nanoparticles, contact-independent bactericidal compounds, or even lantibiotics, which can partially justify our results [49,50]. Classical furunculosis, which is caused by A. salmonicida, is one of most impactful bacterial diseases in aquaculture, causing an important economic impact, as this species generally causes an acute fatal hemorrhagic septicemic disease [46]. Furthermore, none of the isolates inhibited A. hydrophila CECT839, A. hydrophila Interestingly, the bacterial strains isolated from the rotifer tank inhibited ichthyopathogens of paramount importance in turbot larviculture and mariculture, such as A. salmonicida [45], E. tarda [46], V. anguillarum [47], and St. parauberis [48].…”

“…The direct antimicrobial activity as determined by a SOAT, and the scores reflect the ranges of growth inhibition (diameter of the inhibition zones in mm): -, no inhibition; +, <5 mm; ++, ≥5-10 mm; +++, ≥10 mm. Interestingly, the bacterial strains isolated from the rotifer tank inhibited ichthyopathogens of paramount importance in turbot larviculture and mariculture, such as A. salmonicida [45], E. tarda [46], V. anguillarum [47], and St. parauberis [48]. Although A. salmonicida CECT4237 was sensitive to all the LAB isolates, none of them inhibited A. salmonicida CECT894.…”

“…Classical furunculosis, which is caused by A. salmonicida, is one of most impactful bacterial diseases in aquaculture, causing an important economic impact, as this species generally causes an acute fatal hemorrhagic septicemic disease [46]. Furthermore, none of the isolates inhibited A. hydrophila CECT839, A. hydrophila Interestingly, the bacterial strains isolated from the rotifer tank inhibited ichthyopathogens of paramount importance in turbot larviculture and mariculture, such as A. salmonicida [45], E. tarda [46], V. anguillarum [47], and St. parauberis [48]. Although A. salmonicida CECT4237 was sensitive to all the LAB isolates, none of them inhibited A. salmonicida CECT894.…”

Bacteriophage EPP-1, a potential antibiotic alternative for controlling edwardsiellosis caused by Edwardsiella piscicida while mitigating drug-resistant gene dissemination

“…Phage therapy in the field of aquaculture is now being researched against Vibrio , Flavobacterium , Aeromonas , Pseudomonas , and Lactococcus and has yielded favorable outcomes 16 , 17 . Available evidence suggests that administration of E. tarda phage vB_EtaM_ET-ABTNL-9 by feeding, injection, or immersion significantly reduced mortality as well as nonspecific immune-related enzyme activities of turbot Scophthalmus maximus 18 . Furthermore, a phage cocktail composed of E. tarda phage PETp9 and V. harveyi phage PVHp5 significantly reduced host levels of pathogens and maintained the normal gut microbiota profile for ascites prevention in turbot 19 .…”

Controlling edwardsiellosis caused by Edwardsiella piscicida and mitigating drug-resistant gene dissemination: Bacteriophage EPP-1, a promising antibiotic alternative

“…Phage therapy in the eld of aquaculture is now being researched against Vibrio, Flavobacterium, Aeromonas, Pseudomonas, and Lactococcus and has yielded favorable outcomes (Culot et al, 2019;Liu et al, 2022). Available evidence suggests that administration of E. tarda phage vB_EtaM_ET-ABTNL-9 by feeding, injection, or immersion signi cantly reduced mortality as well as nonspeci c immune-related enzyme activities of turbot Scophthalmus maximus (Cui et al, 2022a). Furthermore, a phage cocktail composed of E. tarda phage PETp9 and V. harveyi phage PVHp5 signi cantly reduced host levels of pathogens and maintained the normal gut microbiota pro le for ascites prevention in turbot (Cui et al, 2022b).…”