Potential for Combined Biocontrol Activity against Fungal Fish and Plant Pathogens by Bacterial Isolates from a Model Aquaponic System

Ivaylo Sirakov,Matthias Lutz,Theo Smits,Yordan Staykov,Ranka Junge,Alex Mathis,Andreas Graber

doi:10.3390/w8110518

Ivaylo Sirakov, Matthias Lutz + Show 5 more

Open Access

https://doi.org/10.3390/w8110518

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Abstract

One of the main challenges in aquaponics is disease control. One possible solution for this is biological control with organisms exerting inhibitory effects on fish and plant pathogens. The aim of this study was to examine the potential of isolating microorganisms that exert an inhibitory effect on both plant and fish pathogens from an established aquaponic system. We obtained 924 isolates on selective King’s B agar and 101 isolates on MRS agar from different compartments of a model aquaponic system and tested them for antagonism against the plant pathogen Pythium ultimum and fish pathogen Saprolegnia parasitica. Overall, 42 isolates were able to inhibit both fungi. Although not yet tested in vivo, these findings open new options for the implementation of biological control of diseases in aquaponics, where plants and fish are cultivated in the same water recirculating system.

Highlights

Projections show that the human population will increase up to 9 billion in 2050
The aquaponics system at the Aquaponics laboratory of ZHAW was sampled in 2013 at the different compartments to obtain a representation of the entire bacterial community
The in vitro tests presented in this paper show on the other hand that it is possible to isolate biocontrol organisms on selective media that inhibit the growth of the plant pathogen P. ultimum and the fish pathogen S. parasitica with about the same effectiveness against both diseases

Summary

Introduction

Projections show that the human population will increase up to 9 billion in 2050. food production must increase by 34% to 70% in comparison with today [1]. One technology which has the potential to meet the aforementioned characteristics and could fairly be named a “technology of the future” is aquaponics (AP) [2]. One of the main challenges to successful aquaponics operation is connected with disease control Pathogens can affect both main products: the fish in the aquaculture, and the plants in the hydroponic section. Medicines and chemicals for treating fish parasites and diseases cannot be applied, as plants may absorb and accumulate them [6] This could cause harm to human health when consuming the crop products, as, for example, antibiotics entering the gastrointestinal tract of humans at concentrations below the minimum inhibitory concentration (MIC) may contribute to the enhancement of antibiotic resistance [7]

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