Bacterial Metabolites Produced Under Iron Limitation Kill Pinewood Nematode and Attract Caenorhabditis elegans

Abstract

Pine Wilt Disease (PWD) is caused by Bursaphelenchus xylophilus, the pinewood nematode, and affects several species of pine trees worldwide. The ecosystem of the Pinus pinaster trees was investigated as a source of bacteria producing metabolites affecting this ecosystem: P. pinaster trees as target-plant, nematode as disease effector and its insect-vector as shuttle. For example, metals and metal-carrying compounds contribute to the complex tree-ecosystems. This work aimed to detect novel secondary metabolites like metallophores and related molecules produced under iron limitation by PWD-associated bacteria and to test their activity on nematodes. After screening 357 bacterial strains from Portugal and United States, two promising metallophore-producing strains Erwinia sp. A41C3 and Rouxiella sp. Arv20#4.1 were chosen and investigated in more detail. The genomes of these strains were sequenced, analyzed, and used to detect genetic potential for secondary metabolite production. A combinatorial approach of liquid chromatography-coupled tandem mass spectrometry (LC-MS) linked to molecular networking was used to describe these compounds. Two major metabolites were detected by HPLC analyses and described. One HPLC fraction of strain Arv20#4.1 showed to be a hydroxamate-type siderophore with higher affinity for chelation of Cu. The HPLC fraction of strain A41C3 with highest metal affinity showed to be a catecholate-type siderophore with higher affinity for chelation of Fe. LC-MS allowed the identification of several desferrioxamines from strain Arv20#4.1, in special desferrioxamine E, but no hit was obtained in case of strain A41C3 which might indicate that it is something new. Bacteria and their culture supernatants showed ability to attract C. elegans. HPLC fractions of those supernatant-extracts of Erwinia strain A41C3, enriched with secondary metabolites such as siderophores, were able to kill pinewood nematode. These results suggest that metabolites secreted under iron limitation have potential to biocontrol B. xylophilus and for management of Pine Wilt Disease.

Characterization of the Skin Cultivable Microbiota Composition of the Frog Pelophylax perezi Inhabiting Different Environments

“…Four Acinetobacter strains from different species resisted 75% of AMD and two of them produced a high yield of EPS. Among the mechanisms of detoxification recognized in bacteria, the sequestration of extracellular (biosorption) and intracellular (bioaccumulation) metals [ 65 , 66 ], and the production and secretion of chelating molecules such as siderophores [ 67 ] are considered efficient. A Serratia strain was found among the ones particularly resistant to AMD exposure.…”

Flavin-dependent N-hydroxylating enzymes: distribution and application

“…3a). It is produced by various actinobacteria and often the major component of a metabolite cocktail of related desferrioxamines or bisucaberins secreted by the producer strain (Senges et al 2018;Schwabe et al 2018;Proença et al 2019). The production starts from lysine via cadaverine as a substrate of an N-hydroxylating flavoprotein to yield N 5 -hydroxycadaverine.…”

Screening for Microbial Metal-Chelating Siderophores for the Removal of Metal Ions from Solutions

“…The metal binding spectrum of the Nocardioides siderophore corresponds to the literature, assuming the production of desferrioxamine siderophores. Apart from iron, DFOB and DFOE have been reported to form stable complexes with Ga, Al, In [ 82 , 83 , 84 ], V [ 83 , 85 ], Cr [ 86 ], and REE [ 87 ]. DFOB exhibits higher binding affinities towards Ga(III) (logβ 110 = 28.1) than In(III) (logβ 110 = 20.1) [ 82 ].…”