Abstract

Janthinobacterium spp. are normally considered non-pathogenic, and few pathogenesis-related studies have been reported. Here, we report the first isolation of Janthinobacterium lividum in Korea as a pathogenic bacterium infecting rainbow trout. Mass mortality was observed at one rainbow trout hatchery, and dead fish were necropsied. Gram-negative, nonmotile, rod-shaped bacteria that grew on Cytophaga agar were isolated. A specific violet pigmentation was observed after 7 days of cultivation, and the species were characterized on the basis of the analysis of the 16S rRNA gene. Because no research has focused so far on the pathogenicity of these bacteria, our study was directed to their pathogenic role based on infection-induced histopathology. Examination of stained tissue sections revealed severe renal bacteraemia and tubule degeneration. Other tissue sections, including sections from the liver and the spleen, were relatively clear. The measured half-maximal lethal dose (LD50) was approximately 3 × 105 colony-forming units/fish, suggesting that this bacterium may be an opportunistic pathogen in rainbow trout fisheries. Since the bacterium commonly dwells in soil and most water for rainbow trout fisheries in Korea is supplied from ground water, the bacteria may naturally flow into the aquatic environment. Therefore, recognition of any pathogenic role of J. lividum is important for the prevention of disease in aquaculture.

Highlights

  • Janthinobacterium lividum is a purple-pigmented rod-shaped Gram-negative bacterium of the phylum Proteobacteria, family Oxalobacteraceae [1]

  • Since no research has been conducted regarding the pathogenic role and infection mechanism of Janthinobacterium spp., our study focused on understanding its infection process through histopathological interpretation

  • To verify the pathogenicity of the bacteria in the experimental fish, the same procedure was antibiotics but it is susceptible to doxycycline and trimethoprim–sulfamethoxazole

Read more

Summary

Introduction

Janthinobacterium lividum is a purple-pigmented rod-shaped Gram-negative bacterium of the phylum Proteobacteria, family Oxalobacteraceae [1]. It is commonly isolated from the microbiota of forest soils, Antarctic glaciers, and lake and river water [2]. The pigmentation is the result of the compound violacein, which is produced by the biochemical activity of the organism during metabolism [3]. This production of violacein is a response of the microorganism to environmental stresses and contributes to its defence against external danger [3]. Violacein is produced by bacterial strains of various genera, including Janthinobacterium, Duganella, Collimonas, and Pseudoalteromonas [4]

Methods
Results
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call