Publications of Gilles Stouvenakers
Bookmark and Share    
Full Text
See detailStandardization of Plant Microbiome Studies: Which Proportion of the Microbiota is Really Harvested?
Sare, Abdoul Razack ULiege; Stouvenakers, Gilles ULiege; Eck, Mathilde ULiege et al

in Microorganisms (2020), 8(3), 342

Studies in plant-microbiome currently use diverse protocols, making their comparison difficult and biased. Research in human microbiome have faced similar challenges, but the scientific community proposed ... [more ▼]

Studies in plant-microbiome currently use diverse protocols, making their comparison difficult and biased. Research in human microbiome have faced similar challenges, but the scientific community proposed various recommendations which could also be applied to phytobiome studies. Here, we addressed the isolation of plant microbiota through apple carposphere and lettuce root microbiome. We demonstrated that the fraction of the culturable epiphytic microbiota harvested by a single wash might only represent one-third of the residing microbiota harvested after four successive washes. In addition, we observed important variability between the efficiency of washing protocols (up to 1.6-fold difference for apple and 1.9 for lettuce). QIIME2 analysis of 16S rRNA gene, showed a significant difference of the alpha and beta diversity between protocols in both cases. The abundance of 76 taxa was significantly different between protocols used for apple. In both cases, differences between protocols disappeared when sequences of the four washes were pooled. Hence, pooling the four successive washes increased the alpha diversity for apple in comparison to a single wash. These results underline the interest of repeated washing to leverage abundance of microbial cells harvested from plant epiphytic microbiota whatever the washing protocols, thus minimizing bias. [less ▲]

Detailed reference viewed: 60 (14 ULiège)
Full Text
See detailAquaponic water, a novel source of biocontrol agents against pythium aphanidermatum root rot in lettuce
Stouvenakers, Gilles ULiege; Massart, Sébastien ULiege; Jijakli, Haissam ULiege

Poster (2020, January 31)

In aquaponics, phytosanitary treatments for plant diseases management are a delicate matter because of the presence of fish. However, it appears that aquaponic systems could be naturally armed against ... [more ▼]

In aquaponics, phytosanitary treatments for plant diseases management are a delicate matter because of the presence of fish. However, it appears that aquaponic systems could be naturally armed against plant pathogens. This natural protective action is called suppressiveness. Aquaponic water has shown a direct inhibitory effect on in vitro Pythium spp. growth (Gravel et al. 2015; Sirakov et al. 2016; Stouvenakers et al. 2018). To confirm this discovery, in vivo experiments using Pythium aphanidermatum have been carried out on lettuces growing in hydroponic (HP) water, aquaponic (AP) water or aquaponic water complemented (COMP) with mineral nutrients to reach HP levels. Suppressiveness property of AP, COMP and HP waters was evaluated by comparing root symptoms and lettuces yields. For each treatments, lettuces root microbiota were analysed after Illumina high throughput sequencing of ITS and 16S rDNA genes. Results showed that yields and roots health of AP lettuces were significantly better compared to COMP and HP lettuces. The bioinformatics analysis of sequenced microbiota showed differences in terms of microbiota diversity and features composition when comparing AP with COMP and HP water. These results highlight that the physicochemical modifications of the AP water to make the COMP water disturb the AP microbiota and lead to the loss of its suppressive capacity. Moreover, AP could be an interesting source of novel biocontrol agents for plant pathogens control in aquaponics. [less ▲]

Detailed reference viewed: 118 (6 ULiège)
Full Text
See detailChapter 14: Plant Pathogens and Control Strategies in Aquaponics
Stouvenakers, Gilles ULiege; Dapprich, Peter; Massart, Sébastien ULiege et al

in Goddek, Simon; Joyce, Alyssa; Kotzen, Benz (Eds.) et al Aquaponics Food Production Systems: Combined Aquaculture and Hydroponic Production Technologies for the Future (2019)

Among the diversity of plant diseases occurring in aquaponics, soil-borne pathogens, such as Fusarium spp., Phytophthora spp. and Pythium spp., are the most problematic due to their preference for humid ... [more ▼]

Among the diversity of plant diseases occurring in aquaponics, soil-borne pathogens, such as Fusarium spp., Phytophthora spp. and Pythium spp., are the most problematic due to their preference for humid/aquatic environment conditions. Phytophthora spp. and Pythium spp. which belong to the Oomycetes pseudo-fungi require special attention because of their mobile form of dispersion, the so-called zoospores that can move freely and actively in liquid water. In coupled aquaponics, curative methods are still limited because of the possible toxicity of pesticides and chemical agents for fish and beneficial bacteria (e.g. nitrifying bacteria of the biofilter). Furthermore, the development of biocontrol agents for aquaponic use is still at its beginning. Consequently, ways to control the initial infection and the progression of a disease are mainly based on preventive actions and water physical treatments. However, suppressive action (suppression) could happen in aquaponic environment considering recent papers and the suppressive activity already highlighted in hydroponics. In addition, aquaponic water contains organic matter that could promote establishment and growth of heterotrophic bacteria in the system or even improve plant growth and viability directly. With regards to organic hydroponics (i.e. use of organic fertilisation and organic plant media), these bacteria could act as antagonist agents or as plant defence elicitors to protect plants from diseases. In the future, research on the disease suppressive ability of the aquaponic biotope must be increased, as well as isolation, characterisation and formulation of microbial plant pathogen antagonists. Finally, a good knowledge in the rapid identification of pathogens, combined with control methods and diseases monitoring, as recommended in integrated plant pest management, is the key to an efficient control of plant diseases in aquaponics. [less ▲]

Detailed reference viewed: 52 (7 ULiège)
Full Text
See detailEffect of Plant Growth Promoting Rhizobacteria on aphids reproduction and feeding behaviour
Quaghebeur, Céleste; Serteyn, Laurent ULiege; Stouvenakers, Gilles ULiege et al

Poster (2018, August)

Some soil bacteria belonging to the Bacillus and Pseudomonas genera are particularly efficient biocontrol agents as Plant Growth Promoting Rhizobacteria (PGPR) by showing strong antagonistic activity ... [more ▼]

Some soil bacteria belonging to the Bacillus and Pseudomonas genera are particularly efficient biocontrol agents as Plant Growth Promoting Rhizobacteria (PGPR) by showing strong antagonistic activity toward plant pathogens and inducing systemic resistance (ISR). Beside plant pathogen microbial agents, phytophagous insects should also be impacted by ISR in host plants. Particularly, aphids are considered as herbivore models closed to fungal and bacterial plant pathogens when comparing host plant induced defense mechanisms after aphid attacks. Then, PGPR could play a primary role in interspecific interactions related to plants and aphids including changes in aphid behaviour. This poster shows the preliminary results of our work on interactions between PGPR, host plant and aphids. Among them, we can highlight the induction of phytohormones by PGPR application and the resulting changes in reproduction and feeding behavior of aphids. It seems that secundary endosymbionts play a preponderant role in aphid’s tolerance of elicitated plants. More researches are in progress, based on these trends. Further works will focus on the volatile organic compounds potentially involved in that response and their actual impact on host plant selection by aphids. [less ▲]

Detailed reference viewed: 34 (7 ULiège)
See detailSuppressive effect of aquaponic water on the development of root rot caused by Pythium aphanidermatum in lettuce
Stouvenakers, Gilles ULiege; Massart, Sébastien ULiege; Jijakli, Haissam ULiege

Conference (2018, April 24)

Aquaponic systems, define as recirculating soilless systems combining aquaculture and hydroponic, are at the core of innovative researches. However, plant pest and more especially plant pathogens ... [more ▼]

Aquaponic systems, define as recirculating soilless systems combining aquaculture and hydroponic, are at the core of innovative researches. However, plant pest and more especially plant pathogens management is still unclear. In fact, in this kind of one loop device, where the nutrient plant solution returns to the fish part, chemical pesticides and disinfecting agents are not allowed due to the presence of fishes. Furthermore, they might be toxic for beneficial bacteria present in the system, such as nitrifying bacteria. Among the large possibility of diseases occurring in soilless systems, oomycetes pseudo-fungi, responsible of root rot diseases like Pythium aphanidermatum (Edson) Fitzp, are problematics due to their capacity to produce a mobile form, making the dispersion of the disease easier. Two recent articles open the hypothesis of a natural protective action of aquaponic water or fish effluents against plant pathogens during in vitro trials (Gravel et al., 2015; Sirakov et al., 2016). This phenomenon could be linked to the presence of antagonistic microorganisms or inhibitory compounds in fish water. Assumptions that don’t seem aberrant in light of suppressive action already observed in hydroponic systems (Postma et al., 2008). To confirm these observations, in vitro experiments with aquaponic water have been carried out and completed for the first time with in vivo trials to assess its capacity to procure a plant protection effect towards P. aphanidermatum. In vitro results show a very highly significant decrease of mycelium production when 25% of aquaponic water is added to a V8 CaCO3 broth. But no difference was made between the control (standard V8 CaCO3 broth) and the broth containing 25% of 0.2 µm filtrated aquaponic water. Based on this test, inhibitory action of aquaponic water seems to be linked to a microbial action. Nevertheless, an indirect action on pathogens by the way of plant stimulation by water compounds cannot be totally excluded. During in vivo tests, aquaponic lettuces inoculated with P. aphanidermatum have significantly less disease symptoms and a better root yields compared with inoculated lettuces grown with hydroponic water. These results highlight that aquaponic water can contribute to find a novel source of BCAs. To complete the study, water samples of both experimentations were conserved for 16S rDNA Illumina sequencing, in order to identify bacteria potentially antagonist against P. aphanidermatum. [less ▲]

Detailed reference viewed: 271 (24 ULiège)
See detailBIOCONTROL PROPERTIES OF RECIRCULATING AQUACULTURE WATER AGAINST HYDROPONIC ROOT PATHOGENS
Stouvenakers, Gilles ULiege; Massart, Sébastien ULiege; Jijakli, Haissam ULiege

Conference (2017, October 18)

Integrated recirculated systems combining aquaculture and hydroponic, known as aquaponic systems, are today more and more studied. However one critical management point is still unclear, namely plant pest ... [more ▼]

Integrated recirculated systems combining aquaculture and hydroponic, known as aquaponic systems, are today more and more studied. However one critical management point is still unclear, namely plant pest management. In aquaponics, diseases found in the system are commonly the same than in hydroponics. Root pathogens and more specially oomycetes fungi responsible of root rot are among the most problematic due to their capacity of dispersion linked to zoospores production. On the other hand, compared with hydroponics, aquaponic plants production can give similar yields with less mineral nutrients concentration and even better yields for equivalent concentration in the nutritive solution (Pantanella et al., 2010; Delaide et al., 2016; Saha et al., 2016; Suhl et al., 2016). Furthermore one article opens the hypothesis of an in vitro protective activity of fish effluents versus plant pathogens (Gravel et al., 2015). Both phenomena could be linked to microorganisms or compounds present in fish water. Assumptions that don’t seem aberrant in light of suppressive action already observed in hydroponic systems (Postma et al., 2008). In addition, microorganisms potentially involving in this action could be richer because of organic compounds in aquaponic water. To confirm these observations, in vitro and in vivo experimentations have been made on the ability of recirculating aquaculture water to procure a plant protection effect towards Pythium aphanidermatum (Edson) Fitzp, an oomycetes pathogen. Firsts in vitro results show a significant decrease of mycelium production when 25% of fish water is present in a V8 CaCO3 broth. But no difference was made between the control and the broth containing 25% of 0,2 µm filtrated fish water. These finding highlight a direct microbial antagonist activity of recirculating aquaculture water against P. aphanidermatum. However dissolved compounds don’t display a direct action on this pathogen but biostimulation or elicitation effect on plants can’t be excluded. [less ▲]

Detailed reference viewed: 154 (10 ULiège)
See detailSatellites, LED, aquaponie: l'agriculture réinventée
Jijakli, Haissam ULiege; Stouvenakers, Gilles ULiege

Article for general public (2016)

Detailed reference viewed: 62 (20 ULiège)
Full Text
See detailCharacterization and biocontrol properties of Lactuca sativa rhizosphere microbiota in an aquaponic system
Stouvenakers, Gilles ULiege; Massart, Sébastien ULiege; Jijakli, Haissam ULiege

Poster (2016, May 17)

Aquaponics is an integrated recirculated system that combines aquaculture and hydroponic plant production. The dissolved nutrients generated by the fish rearing after bacterial activities are used by the ... [more ▼]

Aquaponics is an integrated recirculated system that combines aquaculture and hydroponic plant production. The dissolved nutrients generated by the fish rearing after bacterial activities are used by the plants for their growth. This uptake reduces the accumulation of some molecules which allow a longer water recirculation. When comparing growth conditions between aquaponics and hydroponics, we observed much lower concentration of several key nutrients in aquaponics. Nevertheless, several experimentations report similar or better yield in aquaponics compared with hydroponics. One explanation of this phenomenon could be linked to microbial actions. Nowadays, microorganisms related to aquaculture and hydroponics are well characterized but very little is known about the microbiota associated with aquaponic system. The first aim of this study is to characterize the rhizosphere microbiota (metagenomics) of lettuces growing in an aquaponics system. A NGS approach targeting the 16S rDNA will be carried out to evaluate the bacterial composition and diversity. The second aim is to assess the resistance of aquaponics lettuces following a pest introduction. Yields, symptoms and microbial changes due to the pest will be recorded and analysed to determine if aquaponics systems provide a better plant protection than hydroponics. Depending on the results, the final steps will be to identify the optimal conditions for the management of the potential beneficial microbiota or isolate a beneficial microorganism. [less ▲]

Detailed reference viewed: 310 (20 ULiège)