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Vargas-González A, Barajas M, Pérez-Sánchez T. 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 (Basel) 2024; 14:200. [PMID: 38254369 PMCID: PMC10812622 DOI: 10.3390/ani14020200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 12/26/2023] [Accepted: 01/04/2024] [Indexed: 01/24/2024] Open
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.
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Affiliation(s)
- Augusto Vargas-González
- Biochemistry Area, Health Science Department, Faculty of Health Sciences, Public University of Navarra, 31008 Pamplona, Spain;
| | - Miguel Barajas
- Biochemistry Area, Health Science Department, Faculty of Health Sciences, Public University of Navarra, 31008 Pamplona, Spain;
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Standish I, McCann R, Puzach C, Leis E, Bailey J, Dziki S, Katona R, Lark E, Edwards C, Keesler B, Reichley S, King S, Knupp C, Harrison C, Loch T, Phillips K. Development of duplex qPCR targeting Carnobacterium maltaromaticum and Vagococcus salmoninarum. J Fish Dis 2022; 45:667-677. [PMID: 35195301 DOI: 10.1111/jfd.13592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 01/21/2022] [Accepted: 01/22/2022] [Indexed: 06/14/2023]
Abstract
In November 2018, Vagococcus salmoninarum was identified as the causative agent of a chronic coldwater streptococcosis epizootic in broodstock brook trout (Salvelinus fontinalis) at the Iron River National Fish Hatchery in Wisconsin, USA. By February 2019, the epizootic spread to adjacent raceways containing broodstock lake trout (Salvelinus namaycush), whereby fish were found to be coinfected with Carnobacterium maltaromaticum and V. salmoninarum. To differentiate these two pathogens and determine the primary cause of the lake trout morbidity, a quantitative real-time PCR (qPCR) was developed targeting the C. maltaromaticum phenylalanyl-tRNA synthase alpha subunit (pheS) gene. The qPCR was combined with a V. salmoninarum qPCR, creating a duplex qPCR assay that simultaneously quantitates C. maltaromaticum and V. salmoninarum concentrations in individual lake trout tissues, and screens presumptive isolates from hatchery inspections and wild fish from national fish hatchery source waters throughout the Great Lakes basin. Vagococcus salmoninarum and C. maltaromaticum were co-detected in broodstock brook trout from two tribal hatcheries and C. maltaromaticum was present in wild fish in source waters of several national fish hatcheries. This study provides a powerful new tool to differentiate and diagnose two emerging Gram-positive bacterial pathogens.
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Affiliation(s)
- Isaac Standish
- La Crosse Fish Health Center, United States Fish and Wildlife Service, Onalaska, Wisconsin, USA
| | - Rebekah McCann
- La Crosse Fish Health Center, United States Fish and Wildlife Service, Onalaska, Wisconsin, USA
| | - Corey Puzach
- La Crosse Fish Health Center, United States Fish and Wildlife Service, Onalaska, Wisconsin, USA
| | - Eric Leis
- La Crosse Fish Health Center, United States Fish and Wildlife Service, Onalaska, Wisconsin, USA
| | - Jennifer Bailey
- La Crosse Fish Health Center, United States Fish and Wildlife Service, Onalaska, Wisconsin, USA
| | - Sara Dziki
- La Crosse Fish Health Center, United States Fish and Wildlife Service, Onalaska, Wisconsin, USA
| | - Ryan Katona
- La Crosse Fish Health Center, United States Fish and Wildlife Service, Onalaska, Wisconsin, USA
| | - Ellen Lark
- La Crosse Fish Health Center, United States Fish and Wildlife Service, Onalaska, Wisconsin, USA
| | - Carey Edwards
- Iron River National Fish Hatchery, United States Fish and Wildlife Service, Iron River, Wisconsin, USA
| | - Brandon Keesler
- Iron River National Fish Hatchery, United States Fish and Wildlife Service, Iron River, Wisconsin, USA
| | - Stephen Reichley
- Clear Springs Foods, Buhl, Idaho, USA
- College of Veterinary Medicine and Global Center for Aquatic Food Security, Mississippi State University, Starkville, Mississippi, USA
| | | | - Christopher Knupp
- College of Agriculture and Natural Resources, Michigan State University, East Lansing, Michigan, USA
| | - Courtney Harrison
- College of Agriculture and Natural Resources, Michigan State University, East Lansing, Michigan, USA
| | - Thomas Loch
- College of Agriculture and Natural Resources, Michigan State University, East Lansing, Michigan, USA
- College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Kenneth Phillips
- La Crosse Fish Health Center, United States Fish and Wildlife Service, Onalaska, Wisconsin, USA
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Torres-Corral Y, Santos Y. Development of a real-time PCR assay for detection and quantification of Streptococcus iniae using the lactate permease gene. J Fish Dis 2021; 44:53-61. [PMID: 32959452 DOI: 10.1111/jfd.13267] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 08/21/2020] [Accepted: 08/24/2020] [Indexed: 06/11/2023]
Abstract
The aim of this study is the development and evaluation of a rapid and accurate quantitative PCR (qPCR)-based protocol for detection of zoonotic pathogen Streptococcus iniae in bacterial cultures and tissues of diseased fish. For this purpose, the lactate permease-encoding (lldY) gene was selected as a target for the design of S. iniae-specific primers based on comparative genomic analysis using 45 sequences retrieved from NCBI genome database. Specificity and applicability of these primers were tested using 115 bacterial strains and fish tissues infected with S. iniae. Sensitivity, reproducibility and efficiency of qPCR assay were also determined. The developed qPCR assay showed 100% specificity with pure bacterial cultures or DNA extracted from S. iniae or tissues of fish infected with the bacterium. The method has high sensitivity with a detection limit of 1.12 × 101 amplicon copies per assay (equivalent to 2 × 10-9 ng/µl) using bacterial DNA and of 1.44 × 101 gene copies in tissues of fish infected with S. iniae. In conclusion, this qPCR protocol provides an accurate and sensitive alternative for the identification of S. iniae and its detection on fish tissues that can be implemented as a routine tool in microbiological laboratories.
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Affiliation(s)
- Yolanda Torres-Corral
- Departamento de Microbiología y Parasitología, Instituto de Análisis Químico y Biológico (IAQBUS), Universidad de Santiago de Compostela, Santiago de Compostela, Spain
| | - Ysabel Santos
- Departamento de Microbiología y Parasitología, Instituto de Análisis Químico y Biológico (IAQBUS), Universidad de Santiago de Compostela, Santiago de Compostela, Spain
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Torres-Corral Y, Santos Y. Comparative genomics of Streptococcus parauberis: new target for molecular identification of serotype III. Appl Microbiol Biotechnol 2020; 104:6211-22. [PMID: 32440705 DOI: 10.1007/s00253-020-10683-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 05/02/2020] [Accepted: 05/12/2020] [Indexed: 02/06/2023]
Abstract
This paper describes the predicted structure for the cps loci involved in capsule biosynthesis for Streptococcus parauberis serotypes III, IV, and V. Based on the specific serotype regions I, II, and III, a multiplex PCR protocol (mPCR) was designed to differentiate the main serotypes causing fish diseases. A real-time PCR method (qPCR) is also described to identify S. parauberis of serotype III in bacterial cultures and fish tissues. In silico and in vitro analyses revealed that both methods have a 100% specificity. The mPCR assay was optimized for the detection of S. parauberis strains of subtypes Ia (amplicon size 213 bp), subtypes Ib and Ic (both amplicon size 303 bp), serotype II (amplicon size 403 bp), and serotype III (amplicon size 130 bp) from bacterial cultures. The qPCR assay was optimized for the identification and quantification of S. parauberis serotype III strains in bacterial cultures and fish tissues. This assay achieved a sensitivity of 2.67 × 102 gene copies (equivalent to 3.8 × 10-9 ng/μl) using pure bacterial cultures of S. parauberis serotype III and 1.76 × 102 gene copies in fish tissues experimentally and naturally infected with S. parauberis of the serotype III. The specificity and sensitivity of the protocols described in this study suggest that these methods could be used for diagnostic and/or epidemiological purposes in clinical diagnostic laboratories. KEY POINTS: • Structure of loci cps for S. parauberis of serotypes III, IV and V was described. • mPCR to differentiate S. parauberis serotypes causing disease in fish was optimized. • qPCR assay to quantify strains of S. parauberis serotype III in fish tissues.
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Zhang Q, Hu R, Gu Z. A real-time PCR assay for detection of emerging infectious Elizabethkingia miricola. Mol Cell Probes 2020; 52:101571. [PMID: 32289377 DOI: 10.1016/j.mcp.2020.101571] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 04/04/2020] [Accepted: 04/06/2020] [Indexed: 11/22/2022]
Abstract
Elizabethkingia miricola, a Gram-negative bacillus, is emerging as a life-threatening pathogen in both humans and animals. However, no specific and rapid diagnostic method exists to detect E. miricola. Here, we established a real-time PCR assay for the rapid, sensitive, and specific detection of E. miricola with a wide dynamic range of 108 copies/μL to 102 copies/μL. The detection limit of the real-time assay was 145 copies/μL, which was 100 times more sensitive than conventional PCR. All clinical isolates E. miricola from different host species yield very close Tm (80.25 ± 0.25 °C). Additionally, no cross-reaction or false positives were observed in the assay for non-target bacterial species. The performance of this assay was primarily assessed by testing frog tissue samples. Overall, our study provided a real-time PCR assay, which is a rapid, sensitive, and specific diagnostic method that could be used for early diagnosis and epidemiological investigation of E. miricola.
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Standish I, Leis E, Erickson S, McCann R, Puzach C, Katona R, Lark E, Bailey J, Kleman E, Buening J, Edwards C, Loch T, Phillips K. Vagococcus salmoninarum II-qPCR, tropism and egg-associated transmission. J Fish Dis 2020; 43:317-325. [PMID: 32030787 DOI: 10.1111/jfd.13125] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 11/18/2019] [Accepted: 11/19/2019] [Indexed: 06/10/2023]
Abstract
Vagococcus salmoninarum was identified as the causative agent of a chronic epizootic in broodstock "coaster" brook trout (Salvelinus fontinalis) at the Iron River National Fish Hatchery. The epizootic spanned more than a year, was unresponsive to multiple florfenicol treatments, and resulted in >50% mortality of the affected fish. The decision was made to cull the remaining fish during spawning, which presented an opportunity to more thoroughly examine V. salmoninarum sampling methods, organ tropism and vertical transmission. A newly developed qPCR targeting the pheS gene was used in concert with bacterial culture to show that V. salmoninarum indeed disproportionately affects females and has a tropism for female reproductive tissues. The study demonstrates that some female reproductive tissues (e.g. ovarian fluid, unfertilized eggs) are also an effective option for non-lethal detection. Despite the widespread presence of V. salmoninarum in ovarian fluid and on egg surfaces, we found no evidence of intra-ova transmission.
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Affiliation(s)
- Isaac Standish
- United States Fish and Wildlife Service, La Crosse Fish Health Center, Onalaska, WI, USA
| | - Eric Leis
- United States Fish and Wildlife Service, La Crosse Fish Health Center, Onalaska, WI, USA
| | - Sara Erickson
- United States Fish and Wildlife Service, La Crosse Fish Health Center, Onalaska, WI, USA
| | - Rebekah McCann
- United States Fish and Wildlife Service, La Crosse Fish Health Center, Onalaska, WI, USA
| | - Corey Puzach
- United States Fish and Wildlife Service, La Crosse Fish Health Center, Onalaska, WI, USA
| | - Ryan Katona
- United States Fish and Wildlife Service, La Crosse Fish Health Center, Onalaska, WI, USA
| | - Ellen Lark
- United States Fish and Wildlife Service, La Crosse Fish Health Center, Onalaska, WI, USA
| | - Jennifer Bailey
- United States Fish and Wildlife Service, La Crosse Fish Health Center, Onalaska, WI, USA
| | - Eric Kleman
- United States Fish and Wildlife Service, La Crosse Fish Health Center, Onalaska, WI, USA
| | - Jorge Buening
- United States Fish and Wildlife Service, Iron River National Fish Hatchery, Iron River, WI, USA
| | - Carey Edwards
- United States Fish and Wildlife Service, Iron River National Fish Hatchery, Iron River, WI, USA
| | - Thomas Loch
- College of Agriculture and Natural Resources, Michigan State University, East Lansing, MI, USA
- College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
| | - Kenneth Phillips
- United States Fish and Wildlife Service, La Crosse Fish Health Center, Onalaska, WI, USA
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