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 0.25–0.4 mM of nitrophenols after 14 days of incubation. Simultaneously degradation of 3 mM of growth substrate during 1–3 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

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 ( ) • Esteban San Martin Filomena Gomes. CERNAS, Dep. Recursos Florestais, Escola Superior Agrária Coimbra, Bencanta, 3040-316, Coimbra, Portugal, Tel: 351 239 802940, Fax: 351 239 802979, Email: [email protected] Helena Machado INIAV, Instituto Nacional de Investigação Agrária e Veterinária, IP., Av. República, Quinta do Marquês 2780-159 Oeiras, Portugal A. Portugal • 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)