title: Candidate nematicidal proteins in a new Pseudomonas veronii isolate identified by its antagonistic properties against Xiphinema index.
abstract: The nematode Xiphinema index affects grape vines and transmits important viruses associated with fanleaf degeneration. Pseudomonas spp. are an extensive bacterial group in which important biodegradation and/or biocontrol properties can occur for several strains in the group. The aim of this study was to identify new Pseudomonas isolates with antagonist activity against X. index. Forty bacterial isolates were obtained from soil and root samples from Chilean vineyards. Thirteen new fluorescent pseudomonads were found and assessed for their antagonistic capability. The nematicide Pseudomonas protegens CHA0 was used as a control. Challenges of nematode individuals in King's B semi-solid agar Petri dishes facilitated the identification of the Pseudomonas veronii isolate R4, as determined by a 16S rRNA sequence comparison. This isolate was as effective as CHA0 as an antagonist of X. index, although it had a different lethality kinetic. Milk-induced R4 cultures exhibited protease and lipase activities in cell supernatants using both gelatin/tributyrin Petri dish assays and zymograms. Three proteins with these activities were isolated and subjected to mass spectrometry. Amino acid partial sequences enabled the identification of a 49-kDa protease similar to metalloprotease AprA and two lipases of 50 kDa and 69 kDa similar to LipA and ExoU, respectively. Electron microscopy analyses of challenged nematodes revealed degraded cuticle after R4 supernatant treatment. These results represent a new and unexplored property in this species associated with the presence of secretable lipases and protease, similar to characterized enzymes present in biocontrol pseudomonads.
authors.affiliation: Biotechnology Doctoral Program, Universidad Técnica Federico Santa María-Pontificia Universidad Católica de Valparaíso.
authors.forename: Hayron
authors.initials: H
authors.lastname: Canchignia
authors.forename: Fabiola
authors.initials: F
authors.lastname: Altimira
authors.forename: Christian
authors.initials: C
authors.lastname: Montes
authors.forename: Evelyn
authors.initials: E
authors.lastname: Sánchez
authors.forename: Eduardo
authors.initials: E
authors.lastname: Tapia
authors.forename: María
authors.initials: M
authors.lastname: Miccono
authors.forename: Daniel
authors.initials: D
authors.lastname: Espinoza
authors.forename: Carlos
authors.initials: C
authors.lastname: Aguirre
authors.forename: Michael
authors.initials: M
authors.lastname: Seeger
authors.forename: Humberto
authors.initials: H
authors.lastname: Prieto
mesh_terms: D000818:Animals; D000898:Antibiosis; D000969:Antinematodal Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D002677:Chile; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004798:Enzymes / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D013058:Mass Spectrometry; D008854:Microscopy, Electron; D008970:Molecular Weight; D009348:Nematoda / Q000187:drug effects* / Q000648:ultrastructure; D010802:Phylogeny; D018517:Plant Roots / Q000382:microbiology; D011506:Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D011549:Pseudomonas / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D016019:Survival Analysis
chemical_list: D000969:Antinematodal Agents; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D004798:Enzymes; D011506:Proteins; D012336:RNA, Ribosomal, 16S