32 research outputs found
Induction of aromatic ring: cleavage dioxygenases in Stenotrophomonas maltophilia strain KB2 in cometabolic systems
Stenotrophomonas maltophilia KB2 is known to produce different enzymes of dioxygenase family. The aim of our studies was to determine activity of these enzymes after induction by benzoic acids in cometabolic systems with nitrophenols. We have shown that under cometabolic conditions KB2 strain degraded 0.25â0.4Â mM of nitrophenols after 14Â days of incubation. Simultaneously degradation of 3Â mM of growth substrate during 1â3Â days was observed depending on substrate as well as cometabolite used. From cometabolic systems with nitrophenols as cometabolites and 3,4-dihydroxybenzoate as a growth substrate, dioxygenases with the highest activity of protocatechuate 3,4-dioxygenase were isolated. Activity of catechol 1,2- dioxygenase and protocatechuate 4,5-dioxygenase was not observed. Catechol 2,3-dioxygenase was active only in cultures with 4-nitrophenol. Ability of KB2 strain to induce and synthesize various dioxygenases depending on substrate present in medium makes this strain useful in bioremediation of sites contaminated with different aromatic compounds
Arbutoid mycorrhizas of the genus Cortinarius from Costa Rica
Arbutoid mycorrhizas of Comarostaphylis arbutoides (Arbutoidea, Ericaceae) from neotropical montane forests are rarely described. To date, only mycorrhizal associations with the fungal species Leccinum monticola, Leotia lubrica and Sebacina sp. are known from literature. The genus Cortinarius is one of the most species-rich ectomycorrhizal taxa with over 2000 assumed species. In this study, two sites in the Cordillera de Talamanca of Costa Rica were sampled, where Com. arbutoides is endemic and grows together with Quercus costaricensis. Using a combined method of rDNA sequence analysis and morphotyping, 33 sampled mycorrhizal systems of Cortinarius were assigned to the subgenera Dermocybe, Phlegmacium and Telamonia. Specific plant primers were used to identify the host plant. Here, we present the phylogenetic data of all found Cortinarii and describe four of the arbutoid mycorrhizal systems morphologically and anatomically
Leotia cf. lubrica forms arbutoid mycorrhiza with Comarostaphylis arbutoides (Ericaceae)
Arbutoid mycorrhizal plants are commonly found as understory vegetation in forests worldwide where ectomycorrhiza-forming trees occur. Comarostaphylis arbutoides (Ericaceae) is a tropical woody plant and common in tropical Central America. This plant forms arbutoid mycorrhiza, whereas only associations with Leccinum monticola as well as Sebacina sp. are described so far. We collected arbutoid mycorrhizas of C. arbutoides from the Cerro de la Muerte (Cordillera de Talamanca), Costa Rica, where this plant species grows together with Quercus costaricensis. We provide here the first evidence of mycorrhizal status for the Ascomycete Leotia cf. lubrica (Helotiales) that was so far under discussion as saprophyte or mycorrhizal. This fungus formed arbutoid mycorrhiza with C. arbutoides. The morphotype was described morphologically and anatomically. Leotia cf. lubrica was identified using molecular methods, such as sequencing the internal-transcribed spacer (ITS) and the large subunit (LSU) ribosomal DNA regions, as well as phylogenetic analyses. Specific plant primers were used to confirm C. arbutoides as the host plant of the leotioid mycorrhiza
Mycorrhizal synthesis between Pisolithus arhizus and adult clones of Arbutus unedo in vitro and in nursery
Arbutoid mycorrhizae were synthesized between adult selected
clones of Arbutus unedo L. and Pisolithus arhizus. Two micropropagated
clones were tested: AL1, in vitro and C1 (acclimatized plants)
in nursery and later in a field trial. In vitro, rooted shoots were transferred
to test tubes containing the substrate previously inoculated with
mycelium cultured on agar. In the nursery, two inoculation treatments
were tested (vegetative inocula or dry sporocarps) and compared to control
plants. In the field trial, plants from nursery inoculation treatments
were compared and an additional control treatment using seedlings was
implemented. Plant height was evaluated 4 months later in the nursery
and 20 months later in the field trial. Roots were examined by morphological
and histological studies: a) in vitro plantlets one month after
inoculation and nine months after acclimatization; and b) 20 months after
the field trial was established. Arbutoid mycorrhizae were observed in
vitro one month after inoculation, indicating compatibility between A.
unedo and P. arhizus. These showed the presence of a mantle, Hartig net,
and intracellular hyphal complexes confined to the epidermal root cells.
Arbutoid mycorrhizae were also observed nine months after acclimatiza-
Fund project: This work was supported by a PhD fellowship
(SFRH/BD/37170/2007) from the Portuguese Foundation for Science
and Technology (FCT)
The online version is available at http://link.springer.com
Filomena Gomes ( ) âą Esteban San Martin
Filomena Gomes. CERNAS, Dep. Recursos Florestais, Escola Superior
AgrĂĄria Coimbra, Bencanta, 3040-316, Coimbra, Portugal, Tel: 351 239
802940, Fax: 351 239 802979, Email: [email protected]
Helena Machado
INIAV, Instituto Nacional de Investigação Agråria e Veterinåria, IP.,
Av. RepĂșblica, Quinta do MarquĂȘs 2780-159 Oeiras, Portugal
A. Portugal âą Jorge M. Canhoto
Centre of Functional Ecology, Department of Life Sciences, University
of Coimbra, Ap. 3046, 3001-401 Coimbra, Portugal.
Corresponding editor: Chai Ruihai
tion in inoculated and control plants. In order to confirm the identity of
mycorrhizae, molecular techniques were used, in previously inoculated in
vitro plants, 12 months after acclimatization. Thelephora and Hebeloma
mycorrhizae, two types of highly competitive and widespread mycorrhizae
on nurseries were identified. In the nursery, dry sporocarp
treatment improved plant height after four months. In a field trial (20
months later), plants growth did not show significant differences. By this
time, mycorrhized roots with Cenococcum geophilum and other types
were identified. These results and their implications on A. unedo breeding
program are discussed.F. Gomes was supported by a PhD fellowship
(SFRH/BD/37170/2007) from the Portuguese Foundation for
Science and Technology (FCT)