Protective effect of squilla chitosan–silver nanoparticles for Dicentrarchus labrax larvae infected with Vibrio anguillarum

Khouloud M. Barakat,Heba S. El-Sayed,Yousry M. Gohar

doi:10.1007/s40071-016-0133-2

Khouloud M. Barakat, Heba S. El-Sayed + Show 1 more

Open Access

https://doi.org/10.1007/s40071-016-0133-2

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Abstract

Antimicrobial nanoparticle therapy was proposed as an alternative strategy to reduce the use of antibiotics in larval-rearing systems. Antibacterial potential of the prepared squilla chitosan–silver nanoparticles and its protective effect on Dicentrarchus labrax (sea bass) larvae in the early stages were studied against Vibrio angularium. Different concentrations of squilla chitosan (Csq) and squilla chitosan–silver nanoparticles (Csq–AgNps) (1, 2, 5, 10, and 20 %) were, in vitro, tested against V.anguillarum and expressed as a role of Log10 mean. Sea bass larvae were treated using: 10 % Csq and 5 % Csq–AgNps as effective inhibitory concentrations against the pathogen either encapsulated during the feeding regime or added directly to the model system via the water from the onset of 4 weeks. The long-term administration of Csq–AgNps through enriched food for both non-infected and infected systems had survival % of 74.5 ± 1.5 and 72.5 ± 2.5, respectively. Larval clinical observations using Csq–AgNps were studied compared with the two controls. The current study found that 5 % encapsulated Csq–AgNps was enough to suppress infection and considered as an alternative to antibiotics in controlling virulent fish pathogens.

Highlights

Aquaculture is the fastest growing sector of agriculture in the world
The scanning electron microscopy (SEM) micrograph revealed that the chitosan particles are dispersed as individual with a spherical to short rod shape and are homogeneously distributed around 2.10–2.92 lm in diameter (Fig. 2a), while silver nanoform is found with average sizes 22.73–39.77 nm (Fig. 2b)
Results obtained from the growth of V. angularium at different Csq–AgNps concentrations are directly proportional to the reduction in cfu of V. angularium on TCB agar plates

Summary

Introduction

Aquaculture is the fastest growing sector of agriculture in the world. infectious disease is a major impediment to the development of aquaculture and often a menacing problem in farming worldwide (Mohapatra et al 2013). Sea bass (Dicentrarchus labrax) is one of the most economically important fish species in the marine Mediterranean aquaculture (Terova et al 2011) and the most sensitive species to Vibrio anguillarum (Frans et al 2011). V. anguillarum is the causative agent of vibriosis, a fatal haemorrhagic septicaemia, causing significant economic losses in the aquaculture industry (Austin and Austin, 2012). Improper administration of antibiotics against V. anguillarum outbreaks could result in the development of resistant bacteria strains; there is growing interest in finding ways to formulate new natural types of safe and cost-effective biocidal materials (Plant and LaPatra 2011). The impact of many effective active agents on the virulence of V. anguillarum in a highly controlled model system to reduce mortality of sea bass larvae was investigated (Li et al 2014b, 2015; Meloni et al 2015)

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