title: Antagonistic properties of two recombinant strains of Streptomyces melanosporofaciens obtained by intraspecific protoplast fusion.
abstract: Intraspecific protoplast fusion was used to produce stable prototrophic recombinants of Streptomyces melanosporofaciens EF-76, a biocontrol agent of plant disease producing geldanamycin. Two recombinant strains (FP-54 and FP-60) that differed with regard to their antagonistic properties against Bacillus cereus ATCC 14579, Streptomyces scabies EF-35 and Phytophthora fragariae var. rubi 390 were characterized. FP-60 lost the ability to inhibit the in vitro growth of these microbial strains while FP-54 exhibited higher antagonistic activities against them. FP-60 was deficient in geldanamycin biosynthesis whereas FP-54 was shown to produce, in addition to geldanamycin, at least two other antimicrobial compounds that were absent in the culture supernatants of strain EF-76. Like the wild-type strain EF-76, strain FP-54 reduced common scab symptoms on potato tuber but no significant difference was observed between the disease index attributed to tubers treated with strain EF-76 or with strain FP-54. Strain FP-60 showed no protective effect against common scab. The disease index of tubers treated with this recombinant was worse than the index associated with potato tubers from control treatments.
authors.affiliation: Centre d'étude et de valorisation de la diversité microbienne, Département de biologie, Université de Sherbrooke, 2500 Boulevard Université, J1 K 2R1, Sherbrooke, Québec, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Agbessi
authors.forename: J
authors.initials: J
authors.lastname: Beauséjour
authors.forename: C
authors.initials: C
authors.lastname: Déry
authors.forename: C
authors.initials: C
authors.lastname: Beaulieu
mesh_terms: D000900:Anti-Bacterial Agents / Q000096:biosynthesis; D016227:Benzoquinones; D047029:Lactams, Macrocyclic; D008561:Membrane Fusion; D010572:Pest Control, Biological; D010935:Plant Diseases / Q000382:microbiology; D011523:Protoplasts; D011809:Quinones / Q000378:metabolism; D011995:Recombination, Genetic; D013045:Species Specificity; D013302:Streptomyces / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D016227:Benzoquinones; D047029:Lactams, Macrocyclic; D011809:Quinones; C001277:geldanamycin