Haïssam Jijakli - Academia.edu (original) (raw)

Papers by Haïssam Jijakli

Microorganisms

Studies in plant-microbiome currently use diverse protocols, making their comparison difficult an... 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 protocol...

International Journal of Environmental Research and Public Health

This study evaluated the antifungal effects of various volatile organic compounds (VOCs) against ... more This study evaluated the antifungal effects of various volatile organic compounds (VOCs) against two common pathogens: Fusarium culmorum and Cochliobolus sativus. Among the various VOCs, methyl propanoate (MP) and methyl prop-2-enoate (MA) exhibited remarkable antifungal effects under different experimental conditions (direct or indirect contact) and at different concentrations (500–1000 μM). In addition, the type of antifungal effect (fungistatic or fungicidal) appeared to be strongly correlated with the VOC concentrations. Additional tests revealed that both molecules increased membrane permeability of pathogenic spores, which resulted in a decreased efflux of K+ ions into the intracellular medium.

Archives of Agronomy and Soil Science

Journal of Clinical Microbiology

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) has p... more Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) has proved to be a useful diagnostic method for identifying conventional bacteria. In the case of mycobacteria, a good protein extraction protocol is essential in order to obtain reliable identification results. To date, no such protocol has been definitively established. The aim of this study was to compare the manufacturer's recommended protein extraction protocol (protocol A) with two novel protocols (protocols B and C), which apply different freezing temperatures and mechanical disruption times using an automatic tissue homogenizer. A total of 302 clinical isolates, comprising 41 nontuberculous mycobacteria (NTM) species, were grown in parallel on solid and liquid media and analyzed: 174 isolates were slow-growing mycobacteria (SGM) and 128 isolates were rapid-growing mycobacteria (RGM). Overall, MALDI-TOF MS identified a higher number of NTM isolates from solid than from liquid media...

Colloids and Surfaces B: Biointerfaces

Please cite this article as: Deleu M, Deboever E, Nasir MN, Crowet J-Marc, Dauchez M, Ongena M, J... more Please cite this article as: Deleu M, Deboever E, Nasir MN, Crowet J-Marc, Dauchez M, Ongena M, Jijakli H, Fauconnier M-Laure, Lins L, Linoleic and linolenic acid hydroperoxides interact differentially with biomimetic plant membranes in a lipid specific manner, Colloids and Surfaces B: Biointerfaces (2018), https://doi.

Chemistry & biodiversity, 2018

The potential of ions produced in water by the lactoperoxidase system against plant pests has sho... more The potential of ions produced in water by the lactoperoxidase system against plant pests has shown promising results. We tested the bioactivity of ions produced by the lactoperoxidase oxidation of I and SCN in several buffers or in tap water and characterized the ions produced. In vitro biological activity was tested against Penicillium expansum, the causal agent of mold in fruits, and the major cause of patulin contamination of fruit juices and compotes. In buffers, the ionic concentration was increased 3-fold, and pathogen inhibition was obtained down to the 1:15 dilution. In tap water, the ionic concentration was weaker, and pathogen inhibition was obtained only down to the 1:3 dilution. Acidic buffer increased ion concentrations as compared to less acidic (pH 5.6 or 6.2) or neutral buffers, as do increased ionic strength. C-labelled SCN and MS showed that different ions were produced in water and in buffers. In specific conditions the ion solution turned yellow and a product wa...

Scientific reports, Jan 16, 2017

Banana (Musa sp.) ranks fourth in term of worldwide fruit production, and has economical and nutr... more Banana (Musa sp.) ranks fourth in term of worldwide fruit production, and has economical and nutritional key values. The Cavendish cultivars correspond to more than 90% of the production of dessert banana while cooking cultivars are widely consumed locally around the banana belt production area. Many plants, if not all, produce Volatile Organic Compounds (VOCs) as a means of communication with their environment. Although flower and fruit VOCs have been studied for banana, the VOCs produced by the plant have never been identified despite their importance in plant health and development. A volatile collection methodology was optimized to improve the sensitivity and reproducibility of VOCs analysis from banana plants. We have identified 11 VOCs for the Cavendish, mainly (E,E)-α-farnesene (87.90 ± 11.28 ng/μl), methyl salicylate (33.82 ± 14.29) and 6-methyl-5-hepten-2-one (29.60 ± 11.66), and 14 VOCs for the Pacific Plantain cultivar, mainly (Z,E)-α-farnesene (799.64 ± 503.15), (E,E)-α-...

Journal of Phytopathology, 2016

Controlling pests in pre-and postharvest crops using natural and lowimpact products is a major ch... more Controlling pests in pre-and postharvest crops using natural and lowimpact products is a major challenge. The lactoperoxidase system is an enzymatic system that exists in all external secretions in mammals and is part of the non-immune system. We tested its efficacy in in vitro microplates on Phytophthora infestans, Penicillium digitatum, Penicillium italicum, Penicillium expansum and Botrytis cinerea to determine the most suitable concentrations for use. Then, we verified its efficacy in planta under controlled conditions. Solutions prepared with 5.4 mM iodide and 1.2 mM thiocyanate and diluted threefold inhibited pathogen growth in vitro by 63-100%. Twofold-diluted solutions protected potato plants against P. infestans by 60-74% under controlled conditions. Undiluted solution inhibited orange's and apple's postharvest pathogens in curative application with efficacy levels ranging between 84 and 95% in orange and between 63 and 74% in apple. 1.5-fold concentrated solutions inhibited postharvest pathogens of apple in curative application with efficacy levels ranging between 84 and 92%. Our results also show that the oxidative stress response of fruit following wounding could interfere with ion efficiency. Our tests demonstrate for the first time that this biochemical method is as efficient as a conventional synthetic chemical method under controlled conditions. 2011). Then, sexual reproduction spread across northern Europe, leading to higher genetic diversity Cooke et al. 2011; Yuen and Andersson 2013; Wiik 2014). This also increased the capacity of the pathogen to J Phytopathol 165 (2017) 22-34 Ó 2016 Blackwell Verlag GmbH 22 J Phytopathol Penicillium expansum, Penicillium digitatum, Penicillium italicum and Botrytis cinerea cultures

Banana: from origin to market. Cultivated bananas are giant herbaceous plants within the genus Mu... more Banana: from origin to market. Cultivated bananas are giant herbaceous plants within the genus Musa. They are both sterile and parthenocarpic. There are well over a thousand domesticated Musa cultivars, they are mostly triploid (a few are diploid or tetraploid) and are derived from crosses between two wild species, Musa acuminata and Musa balbisiana. In terms of production, bananas are the fourth agricultural product after rice, wheat, and maize. They constitute the basis of food security for many people. Cropping systems vary widely around the world and contrasting objectives are encountered: consumption by the producer, sale on local or national markets, export, etc. Cooking bananas, including plantains, must be distinguished from dessert bananas, which constitute a major international trade. This international trade started only in the early 1900s but it has since grown continuously. Banana is currently the most exported fruit, in terms of both value and quantity. Despite the high genetic diversity found within the genus Musa, the export market is mainly based on single Cavendish. There are major challenges to banana production from biotic or abiotic stresses to continue to meet the criteria of sustainability, quality and yield that are imposed.

BioControl, 2015

The characterization of microbial biological control agents (MBCAs) is crucial to improve their e... more The characterization of microbial biological control agents (MBCAs) is crucial to improve their efficacy and consistency as biopesticides. Powerful approaches to characterize MBCA's modes of action are provided by modern molecular technologies. This paper reviews improvements achieved in this subject by three ''omics'' approaches: namely the genomic, the transcriptomic and the proteomic approaches. The paper discusses the advantages and drawbacks of new molecular techniques and 'discovery driven' approaches to the study of the biocontrol properties against plant pathogens. Omics technologies are capable of: (i) identifying the genome, transcriptome or proteome features of an MBCA strain, (ii) comparing properties of strains/mutants with different biocontrol efficacy, (iii) identifying and characterizing genes, mRNAs and proteins involved in MBCA modes of action, and (iv) simultaneously studying the transcriptome or proteome of the plant host, the plant pathogen and the MBCAs in relation to their bi-or tri-trophic interactions.

Phytopathology, 2001

Ulocladium atrum (strain 385) consistently reduced Botrytis cinerea sporulation on necrotic fragm... more Ulocladium atrum (strain 385) consistently reduced Botrytis cinerea sporulation on necrotic fragments of strawberry leaves. On these tissues, two strains of U. atrum (isolates 18558 and 18559) showed lower antagonistic activities than the reference strain 385. Colonization of strawberry leaflets by the three U. atrum strains appeared similar in the absence of B. cinerea, whether quantified by chitin or immunological assays. The second method (based on anti-U. atrum antibodies) revealed that strawberry leaflet colonization by U. atrum 385 was better than by the other U. atrum strains in the presence of B. cinerea. An immunoassay using anti-B. cinerea antibodies revealed that the colonization of B. cinerea in tissues was lower in the presence of U. atrum 385 than with the two other U. atrum strains. The enzymatic activities produced by U. atrum 385 during the colonization phases of necrotic tissues were compared to B. cinerea and U. atrum strains 18558 and 18559. U. atrum 385 had the ...

Communications in agricultural and applied biological sciences, 2007

Rhizoctonia solani is one of the most important limiting factors for potato production and storag... more Rhizoctonia solani is one of the most important limiting factors for potato production and storage in Belgium and worldwide. Its management is still strongly dependent on chemical treatments. The aim of this work was to evaluate the possibility of exploiting bacteria and fungi in order to control this pathogen. Among a collection of 220 bacterial strains isolated from different organs of healthy potato plants and rhizospheric soils, 25 isolates were selected using screening methods based on in vitro dual culture assays. The mycelial growth inhibition rate of the pathogen was ranged from 59.4 to 95.0%. Also seven fungal strains isolated from the rhizospheric soil and potato roots showed a highly mycelial growth inhibition of R. solani. The mycelial growth inhibition rate obtained with these fungi was included between 60.0 and 99.4%. From this preliminary study, the further investigations will be planned to determine the bacterial isolates systematic, species of fungal strains by usin...

Communications in agricultural and applied biological sciences, 2005

Candida oleophila strain O was previously selected for its high and reliable antagonistic activit... more Candida oleophila strain O was previously selected for its high and reliable antagonistic activity against Botrytis cinerea and Penicillium expansum, two important wound pathogens on post-harvest apples. The application of these antagonistic strains on wound pathogens of Citrus was more recently undertaken. The efficacy of yeast (applied at several concentrations from 10(5) to 10(8) CFU/ml) was assessed against P. digitatum and P. italicum inoculated after one hours (at a concentration of 10(5), 106 and 10(7) spores/ml) on 'Clementine' and 'Valencia late' varieties. The protective levels were positively correlated with high concentration of antagonist and low concentration of pathogen. The antagonistic activity of this strain was also dependent on the incubation time before pathogen inoculation. The protective level increased with time between application of the antagonist and inoculation of fungal spores. Finally, the efficacy of biomass of C. oleophila strain O (pr...

Recent trends in the implementation of bioherbicide use in the control of water hyacinth (Eichhor... more Recent trends in the implementation of bioherbicide use in the control of water hyacinth (Eichhornia crassipes [Martius] Solms Laubach) have depended primarily on several strategies. The use of bioherbicides has been stimulated as part of the search for alternatives to chemical control, as the use of these more environmentally-friendly formulations minimizes hazards resulting from herbicide residue to both human and animal health, and to the ecology. In addition, one of the major strategies in the concept of biological control is the attempt to incorporate biological weed control methods as a component of integrated weed management, in order to achieve satisfactory results while reducing herbicide application to a minimum. Several fungal pathogens with mycoherbicide potential (Sclerotinia sclerotiorum in Hyakill™ and Cercospora rodmanii, named ABG-5003) have been discovered on diseased water hyacinth plants, but none has become commercially available in the market. Biological, technological, and commercial constraints have hindered progress in this area. Many of these constraints are being addressed, but there is a critical need to better understand the biochemical and physiological data regarding the pathogenesis of these new bioherbicides. Oil emulsions are recognized as a way to increase both efficiency of application and efficacy of biocontrol agents.

asphyxie de la vie sous-marine affecte lʼéquilibre de lʼécosystème aquatique. Elle freine égaleme... more asphyxie de la vie sous-marine affecte lʼéquilibre de lʼécosystème aquatique. Elle freine également le transport fl uvial, la pêche et obstrue les prises dʼeau des barrages hydroélectriques et des réseaux dʼirrigation. ont rapporté quʼau regard de la capacité reproductrice de la jacinthe, de son adaptabilité, des conditions alimentaires et de sa résistance aux conditions défavorables, il est jusquʼà présent impossible de lʼéradiquer une fois introduite dans une nouvelle zone. Bien que lʼorigine de lʼinfes-Synthèse bibliographique : problématique de la jacinthe dʼeau, Eichhornia crassipes, dans les régions tropicales et subtropicales du monde, notamment son éradication par la lutte biologique au moyen des phytopathogènes La jacinthe dʼeau probablement originaire dʼAmérique du Sud se développe actuellement entre les 35 e parallèles nord et sud de la planète. Elle a été introduite dans plusieurs régions du monde comme plante ornementale, où elle est devenue plus tard lʼune des plus dangereuses adventices aquatiques dʼeau douce du monde. Son infestation peut être contrôlée par le biais de traitements physiques et chimiques. Cependant, ces techniques de lutte sont souvent coûteuses et dangereuses pour la santé humaine et lʼenvironnement. Dʼautre part, à lʼinstar des législations occidentales, celles des pays en voie de développement sont de plus en plus restrictives sur les substances chimiques autorisées. Dès lors, un intérêt grandissant a été porté aux luttes alternatives parmi lesquelles la lutte biologique. Cette lutte au moyen dʼinsectes, de poissons et de mammifères contre la jacinthe pourrait être renforcée par lʼapplication de mycoherbicides. Ces derniers sont en principe plus respectueux vis-à-vis de lʼenvironnement et de la santé humaine et sembleraient constituer une alternative crédible supplémentaire pour une gestion durable de la jacinthe. Mots-clés. Jacinthe dʼeau, lutte biologique, mycoherbicide, bioherbicide.