Endophytic Bacteria Bacillus subtilis, Isolated from Zea mays, as Potential Biocontrol Agent against Botrytis cinerea

Simple Summary Plant-microorganism associations date back more than 400 million years. Plants host microorganisms that establish many different relationships with them, some negative and others very positive for both organisms. A type of this relationship is established with microorganisms that live inside them, known as endophytic microorganisms; they can include bacteria, yeasts, and fungi. In this study, we isolate endophytic bacteria from maize plants, and we characterize them in order to check their potential for being used as biocontrol agents against Botrytis cinerea, one of the most important phytopathogenic fungi in the world. The endophytic bacteria showed this antagonistic effect during in vitro assay and also during in vivo assay in Phaseolus vulgaris. At the same time, they showed the capacity for promoting growth in Zea mays plants. Plant diseases are one of the main factors responsible for food loss in the world, and 20-40% of such loss is caused by pathogenic infections. Botrytis cinerea is the most widely studied necrotrophic phytopathogenic fungus. It is responsible for incalculable economic losses due to the large number of host plants affected. Today, B. cinerea is controlled mainly by synthetic fungicides whose frequent application increases risk of resistance, thus making them unsustainable in terms of the environment and human health. In the search for new alternatives for the biocontrol of this pathogen, the use of endophytic microorganisms and their metabolites has gained momentum in recent years. In this work, we isolated endophytic bacteria from Zea mays cultivated in Colombia. Several strains of Bacillus subtilis, isolated and characterized in this work, exhibited growth inhibition against B. cinerea of more than 40% in in vitro cultures. These strains were characterized by studying several of their biochemical properties, such as production of lipopeptides, potassium solubilization, proteolytic and amylolytic capacity, production of siderophores, biofilm assays, and so on. We also analyzed: (i) its capacity to promote maize growth (Zea mays) in vivo, and (ii) its capacity to biocontrol B. cinerea during in vivo infection in plants (Phaseolus vulgaris).This research was supported by grants from MINECO-FEDER RTI 2018-097356-B-C21, -B-C22, Research Project FEDER-UCA18-107713, and the University of Cadiz by the "Programa de Fomento e Impulso de la actividad de Investigacion y Transferencia de la Universidad de Cadiz"

In Situ Analysis of Bacterial Lipopeptide Antibiotics by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging

peer reviewe

Chitin mixed in potting soil alters lettuce growth, the survival of zoonotic bacteria on the leaves and associated rhizosphere microbiology

Chitin is a promising soil amendment for improving soil quality, plant growth, and plant resilience. The objectives of this study were twofold. First, to study the effect of chitin mixed in potting soil on lettuce growth and on the survival of two zoonotic bacterial pathogens, Escherichia colt O157:H7 and Salmonella enterica on the lettuce leaves. Second, to assess the related changes in the microbial lettuce rhizosphere, using phospholipid fatty acid (PLFA) analysis and amplicon sequencing of a bacterial 16S rRNA gene fragment and the fungal ITS2. As a result of chitin addition, lettuce fresh yield weight was significantly increased. S. enterica survival in the lettuce phyllosphere was significantly reduced. The E. coli O157:H7 survival was also lowered, but not significantly. Moreover, significant changes were observed in the bacterial and fungal community of the lettuce rhizosphere. PLFA analysis showed a significant increase in fungal and bacterial biomass. Amplicon sequencing showed no increase in fungal and bacterial biodiversity, but relative abundances of the bacterial phyla Acidobacteria, Verrucomicrobia, Actinobacteria, Bacteroidetes, and Proteobacteria and the fungal phyla Ascomycota, Basidiomycota, and Zygomycota were significantly changed. More specifically, a more than 10-fold increase was observed for operational taxonomic units belonging to the bacterial genera Cellvibrio, Pedobacter, Dyadobacter, and Streptomyces and to the fungal genera Lecanicillium and Mortierella. These genera include several species previously reported to be involved in biocontrol, plant growth promotion, the nitrogen cycle and chitin degradation. These results enhance the understanding of the response of the rhizosphere microbiome to chitin amendment. Moreover, this is the first study to investigate the use of soil amendments to control the survival of S. enterica on plant leaves

Rutin and quercetin content in the forage of common buckwheat as affected by maturity and conservation method

The content of rutin and quercetin was examined in fresh, hayed and ensiled forage of common buckwheat. The treatments were two varieties of buckwheat, 'Bamby' and 'Lileja', and two ripening stages of harvest, first green and first brown achenes. In the silage, produced with experimental mini-silos, additional treatments were the wilting of the forage (at 35% dry matter) and the addition of Lactobacillus plantarum as inoculum. The concentration of rutin and quercetin decreased between ripening stages. Flavonoid content was different among varieties, 'Lileja' had the highest rutin concentration (about 20 g kg-1), while 'Bamby' had the highest quercetin concentration (about 0.2 g kg-1). Rutin and quercetin yield reached about 70 kg ha-1 and 500 g ha-1, respectively. The haymaking process reduced the rutin and quercetin concentration in the forage, however, the extent of reduction was higher at the green (-43% for rutin and -55% for quercetin) than at the brown achenes stage (-13% rutin and -26% quercetin). The ensiling process, with the associated bacterial activities, led to the transformation of rutin into quercetin. The decrease of rutin in the silage, compared to fresh forage, ranged between -84 and -99%, while in contrast, the quercetin concentration increased by about 140-200 times. However, the loss of total rutin plus quercetin during ensiling was limited (approximately 5%). Forage wilting negatively affected rutin transformation in quercetin, while bacterial inoculum improved it. These results highlight that the forage of buckwheat could be considered like a dietary supplement rich of flavonoids, with the potential to be used as functional feed

Tourisme et territoire : gérer le passé et préparer l'avenir

Tourisme et territoire : gérer le passer pour préparer l'aveni

Fiches touristiques, Recueil – Volume 1.

editorial reviewedCe recueil de fiches consiste en une caractérisation des équipements touristiques parmi les plus importants en termes de territoire dédié en Wallonie. Le premier volume est principalement consacré aux attractions touristiques. Après un premier chapitre expliquant comment a été conçu le modèle de fiche, quatre types d'attractions sont caractérisées : « Attractions du pôle d'intérêt culturel », « Attractions du pôle d'intérêt naturel », « Attractions du pôle d'intérêt récréatif » et « Golfs ». Une dernière fiche s’intéresse aux « Infrastructures pour foires, salons et congrès ». La description proposée aborde notamment la répartition spatiale de ces différents types d’infrastructures (dont l'emprise au sol pour les équipements de grande taille), leurs caractéristiques touristiques (capacité d'accueil ou fréquentation, reconnaissance officielle et des utilisateurs), leur rapport au territoire (accessibilité, contraintes physiques et légales…) et leur dynamique spatio-temporelle. Avec ces fiches, le premier objectif de la recherche « Tourisme et Territoire : gérer le passé et préparer l'avenir (2020-2022) » était de mobiliser les données disponibles, voire de les créer, afin d’acquérir une meilleure connaissance territoriale du tourisme wallon. Les traitements ont également abouti à des recommandations quant à des améliorations possibles dans la gestion des données touristiques et à des pistes pour approfondir les liens entre les infrastructures touristiques et l’aménagement du territoire.Tourisme et territoire: gérer le passé et préparer l'aveni

Fiches touristiques, Recueil – Volume 2.

editorial reviewedCe recueil de fiches consiste en une caractérisation des équipements touristiques parmi les plus importants en termes de superficies consommées en Wallonie. Ce deuxième volume est dédié aux hébergements utilisés par les touristes. Onze types d’hébergement y sont caractérisés : « Aires d'accueil pour motor-homes », « Campings touristiques », « Centres de tourisme social », « Endroits de camp », « Hébergements issus de plateformes d'échanges (Airbnb, Vrbo / HomeAway) », « Hébergements touristiques de terroir et meublés de vacances », « Hôtels », « Parcs résidentiels de week-end », « Résidences secondaires cadastrales », « Terrains de caravanage », « Villages de vacances ». La description de ces différentes infrastructures aborde notamment leur répartition spatiale (dont l’emprise au sol pour les équipements de grande taille), leurs caractéristiques touristiques (capacité d’accueil ou fréquentation, reconnaissance officielle et par les utilisateurs), leur rapport au territoire (accessibilité, contraintes physiques et légales…) et leur dynamique spatio-temporelle. Avec ces fiches, le premier objectif de la recherche « Tourisme et Territoire : gérer le passé et préparer l'avenir (2020-2022) » était de mobiliser les données disponibles, voire de les créer, afin d’acquérir une meilleure connaissance territoriale du tourisme wallon. Les traitements ont également abouti à des recommandations quant à des améliorations possibles dans la gestion des données touristiques et à des pistes pour approfondir les liens entre les infrastructures touristiques et l’aménagement du territoire. Le premier volume de ce recueil est quant à lui principalement consacré aux attractions touristiques et explique comment a été conçu le modèle de fiche.Tourisme et territoire: gérer le passé et préparer l'aveni