N. Curvetto

Degradation of Metsulfuron Methyl by Agaricus blazei Murrill Spent Compost Enzymes

ABSTRACT Metsulfuron methyl (MM) is an herbicide used in cereal crops. The white rot mushroom Agaricus blazei Murrill is an important edible and medicinal mushroom reported to be a major laccase producer, a lignin-degrading enzyme with low substrate specificity. A search for assaying the potential use of A. blazei spent mushroom compost (SMC) as a remediation tool for cleaning MM polluted soils was carried out. A phytotoxic dose of this herbicide was separately incubated with two enzyme preparations obtained from the SMC after the second mushroom fruiting flush; the phytotoxicity of the resulting reaction mixtures was then assayed by using a plantlet growing test with Brassica napus L. Thus, the crude enzyme SMC extract preparation (I) or the partially purified enzyme SMC extract (II) and their dilutions, 1:10 and 1:100, were mixed with MM (5 × 10−3 ppm final concentration) and incubated at 25°C for 24, 48, 72, and 96 h. Plantlets separately exposed for 72 and 96 h to the resulting reaction mixtures between MM and those enzyme preparations showed a highly significant increase in their hypocotyl length with respect to plantlets exposed to MM alone. It was thus demonstrated the ability that complex enzyme fractions present in A. blazei SMC have to degrade MM during the right incubation time to compounds with no or lower phytotoxicity than this herbicide.

In Vitro Studies of Secondary Metabolite-Related Responses in Some Species of Genus Grifola (Agaricomycetes) from Argentina.

Grifola gargal Singer and Grifola sordulenta (Mont.) Singer mushrooms are related to Grifola frondosa (Dicks.) Gray, which is well known for its medicinal properties. In vitro studies were performed to find a useful guide for optimizing the environmental parameters through biotransformation of lignocellulosic materials and basidiome development, also considering secondary metabolism-related responses (SMRRs) associated with these processes and the variability among species and strains; this optimization is necessary to make the mushrooms industrial cultivation profitable. Morphological features of mycelial cultures revealed that intraspecific variability was of taxonomic relevance. A low ligninolytic capacity in studied Grifola species was observed when compared with 2 control species: G. frondosa and Ganoderma lucidum. Experiments with nutrient media containing different carbohydrate sources indicated that G. gargal mycelia grew better in xylulose and G. sordulenta, in xylulose or cellulose; in addition, the latter species presented cellobiose dehydrogenase activity. An additional study of SMRRs under different light conditions (aroma, pigmentation, and morphogenic manifestations) showed that white light was better than blue, green, or red-filtered light at inducing advanced SMRRs. The results of SMRR stimulation are proposed as useful guidance for optimizing the environmental parameters for bioprocesses aimed at metabolite production.

Towards genetic transformation of local onion varieties

as transfection vectors. Mature embryos from three varieties of ‘Valenciana’ onion, Torrentina, Cobriza INTA and Grano de oro were in vitro cultivated for callus induction. After three to four months an average of 57.4% success for the three varieties was reached. Transformation was carried out with Agl1 or LBA 4404 A.