Diversity of Bacteria Associated with Bursaphelenchus xylophilus and Other Nematodes Isolated from Pinus pinaster Trees with Pine Wilt Disease

Abstract

The pinewood nematode (PWN), Bursaphelenchus xylophilus, has been thought to be the only causal agent of pine wilt disease (PWD), however, since bacteria have been suggested to play a role in PWD, it is important to know the diversity of the microbial community associated to it. This study aimed to assess the microbial community associated with B. xylophilus and with other nematodes isolated from pine trees, Pinus pinaster, with PWD from three different affected forest areas in Portugal. One hundred and twenty three bacteria strains were isolated from PWN and other nematodes collected from 14 P. pinaster. The bacteria strains were identified by comparative analysis of the 16S rRNA gene partial sequence. All except one Gram-positive strain (Actinobacteria) belonged to the Gram-negative Beta and Gammaproteobacteria. Most isolates belonged to the genus Pseudomonas, Burkholderia and to the family Enterobacteriaceae. Species isolated in higher percentage were Pseudomonas lutea, Yersinia intermedia and Burkholderia tuberum. The major bacterial population associated to the nematodes differed according to the forest area and none of the isolated bacterial species was found in all different forest areas. For each of the sampled areas, 60 to 100% of the isolates produced siderophores and at least 40% produced lipases. The ability to produce siderophores and lipases by most isolates enables these bacteria to have a role in plant physiological response. This research showed a high diversity of the microbial community associated with B. xylophilus and other nematodes isolated from P. pinaster with PWD.

Bacteria associated with the pinewood nematode Bursaphelenchus xylophilus collected in Portugal

“…The genus Staphylococcus (1% of isolates) was the only representative of Firmicutes recovered from PWN. These results are in accordance with those presented by Proença et al (Proença et al 2010), who reported that the major phylogenetic groups of bacteria associated with B. xylophilus and other nematodes identified in three different PWD foci in Portugal, were Enterobacteriaeceae (genera Yersinia, Serratia, Pantoea, Erwinia and Ewingella), Burkholderiaceae (genus Burkholderia) and Pseudomonadaceae (genus Pseudomonas).…”

“…Initially, the affected area covered 510,000 ha of maritime pine (Pinus pinaster) forestland, mainly in the Setubal peninsula (Mota et al 1999), but more recently it has been detected in the center of Portugal, in Arganil and Lousã (Proença et al 2010). In Portugal, the bacterial community associated with diverse nematode species found together with PWD foci varies between sampling regions and is mainly composed of the genera Burkholderia and Pseudomonas, as well as other bacteria from the family Enterobacteriaceae (Proença et al 2010).…”

Specific Microbial Attachment to Root Knot Nematodes in Suppressive Soil

“…Genera or species of the bacterial attachments to J2 from the three soils were also found in association with different plantparasitic nematodes in previous studies (8,9,41,42). J2 from the most suppressive soil Kw were often associated with OTU similar to species that were reported to be involved in infectious diseases (Mycoplasma wenyonii, Peptoniphilus gorbachii, Brucella sp., Paracoccus yeei, Neisseria mucosa, and Shigella flexneri).…”

Draft Genome Sequence of Pseudomonas sp. Strain M47T1, Carried by Bursaphelenchus xylophilus Isolated from Pinus pinaster

“…strain M47T1 (classified as Pseudomonas sp. M47T1 [7]) killed B. xylophilus nematodes in vitro within 24 h of incubation (D. N. Proença, unpublished results).…”

“…strain M47T1 was achieved from trails made on R2A by B. xylophilus from a Pinus pinaster with PWD (7). Sequencing of the 16S rRNA gene was performed, and the strain was tested for the ability to kill nematodes (7). Culture supernatants of Gram-negative Pseudomonas sp.…”