title: Diversity of culturable bacterial populations associated to Tuber borchii ectomycorrhizas and their activity on T. borchii mycelial growth.
abstract: Isolation and physiological and molecular characterisation of culturable bacterial strains belonging to actinomycetes, pseudomonads and aerobic spore-forming bacteria were carried out on mycorrhizal root tips of Quercus robur var. peduncolata infected by Tuber borchii. Cellular density of the three bacterial groups in ectomycorrhizal root tips was estimated to be 1.3+/-0.11 x 10(6) cfu g(-1) dry weight for total heterotrophic bacteria and 1.08+/-0.6 x 10(5) (mean+/-S.E.), 1.3+/-0.3 x 10(5) and 1.4+/-0.2 x 10(5) cfu g(-1) dry weight for pseudomonads, actinomycetes and spore-forming bacteria respectively. Identification of pseudomonads by the Biolog system indicated, besides the most represented species Pseudomonas fluorescens (biotypes B, F and G), the occurrence of strains belonging to Pseudomonas corrugata. Amplified ribosomal DNA restriction analysis of actinomycetes and spore formers revealed at least three and six different groups of patterns, respectively. Many bacterial isolates were able to induce variations in growth rates of T. borchii mycelium; among these, 101 strains showed antifungal activity, whereas 17 isolates, belonging to spore formers, were able to increase mycelial growth up to 78% when compared to uninoculated mycelial growth. The potential role of these populations in the development and establishment of mycorrhizas is discussed.
authors.affiliation: Istituto di Biologia e Biotecnologia Agraria C.N.R. (formerly Centro di Studio per la Microbiologia del Suolo, C.N.R.) - Sezione di Pisa, via del Borghetto 80, 56124 Pisa, Italy.
authors.forename: Cristiana
authors.initials: C
authors.lastname: Sbrana
authors.forename: Monica
authors.initials: M
authors.lastname: Agnolucci
authors.forename: Stefano
authors.initials: S
authors.lastname: Bedini
authors.forename: Annamaria
authors.initials: A
authors.lastname: Lepera
authors.forename: Annita
authors.initials: A
authors.lastname: Toffanin
authors.forename: Manuela
authors.initials: M
authors.lastname: Giovannetti
authors.forename: Marco P
authors.initials: MP
authors.lastname: Nuti
mesh_terms: D000192:Actinomycetales / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D001203:Ascomycota / Q000235:genetics / Q000254:growth & development*; D001419:Bacteria / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification*; D018407:Bacterial Physiological Phenomena; D025282:Mycelium / Q000254:growth & development / Q000378:metabolism; D012150:Polymorphism, Restriction Fragment Length; D011549:Pseudomonas / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D013171:Spores, Bacterial / Q000235:genetics / Q000302:isolation & purification; D013559:Symbiosis