Edgardo Albertó

Utilization of new naturally occurring strains and supplementation to improve the biological efficiency of the edible mushroom Agrocybe cylindracea

To evaluate the importance of searching new naturally occurring strains to raise yields in mushroom production, eight wild and four commercial strains of Agrocybe cylindracea were cultivated on wheat straw. The highest biological efficiencies (BE) (54.5–72.4%) were obtained with three wild and two commercial strains when cultured on non-supplemented wheat straw. Rolled oats or soybean flour supplementation were tested using three selected strains, increasing BEs up to 1.2, 0.5 and 0.7-fold, respectively. This effect of supplementation was stronger in the Asiatic wild strain, yielding up to 41.1 and 30% more than the two other strains with rolled oats and soybean flour, respectively. The Asiatic wild strain cultivated with soybean flour supplementation achieved an average biological efficiency of 179%, to our knowledge, the highest reported for this species. These results show the importance of searching for new naturally occurring strains in combination with supplemented wheat straw substrate for raising yields in A. cylindracea cultivation.

Ornithine and arginine decarboxylase activities and effect of some polyamine biosynthesis inhibitors on Gigaspora rosea germinating spores.

The pathways for putrescine biosynthesis and the effects of polyamine biosynthesis inhibitors on the germination and hyphal development of Gigaspora rosea spores were investigated. Incubation of spores with different radioactive substrates demonstrated that both arginine and ornithine decarboxylase pathways participate in putrescine biosynthesis in G. rosea. Spermidine and spermine were the most abundant polyamines in this fungus. The putrescine biosynthesis inhibitors alpha-difluoromethylarginine and alpha-difluoromethylornithine, as well as the spermidine synthase inhibitor cyclohexylamine, slightly decreased polyamine levels. However, only the latter interfered with spore germination. The consequences of the use of putrescine biosynthesis inhibitors for the control of plant pathogenic fungi on the viability of G. rosea spores in soil are discussed.

The genus Pleurotus in Argentina

Macro- and micromorphological characters of specimens of the genus Pleurotus (Fr.) P. Kumm. in Argentina obtained in the field and from different national herbaria were analyzed. Cultivation techniques were used to obtain basidiomata, allowing for a macro- and micromorphological study of fresh developing fruit bodies. We concluded that in Argentina there are, so far, six species, namely P. albidus, P. cystidiosus, P. ostreatus, P. pulmonarius, P. rickii and P. djamor, the latter with three varieties: var. djamor, var. cyathiformis and var. roseus.

Presence of different arbuscular mycorrhizal infection patterns in roots of Lotus glaber plants growing in the Salado River basin

Morphological types of arbuscular mycorrhizal (AM) fungi associated with Lotus glaber in sodic soils of the Salado River basin were studied. At least eight colonization patterns (IP) of AM fungi in roots of L. glaber were observed after 30 plants were analyzed. Arum- and Paris-type infection were found in the same plant species. This result supports the idea that AM morphology is not solely under plant control, but is also influenced by fungal identity. One infection pattern, presumably corresponding to Glomus intraradices, and a second, possibly assignable to Glomus tenue, were the most commonly found. Our results reinforce previous suggestions that G. intraradices is well adapted to sodic-saline conditions and may play a role in the resistance of L. glaber to these soils.

Polyporus tenuiculus: a new naturally occurring mushroom that can be industrially cultivated on agricultural waste.

Polyporus tenuiculus is a naturally occurring species from Central and South America that is consumed by different ethnic groups in the region. To determine the optimal conditions for fruiting body production, two strains were assayed on wheat straw and sawdust with or without supplements. Sixty days of incubation at 25°C were needed to produce a solid block. The highest yield was obtained with strain ICFC 383/00 grown on supplemented willow sawdust. In a second experiment the strain ICFC 383/00 and different supplements were used to improve the biological efficiency (BE) and to determine the quality traits and its biodegradation capacity. The highest yields were obtained on sawdust with 25% of supplements reaching 82.7% of BE. Supplements raised the number of flushes, generally from four to five, contributing to increased yields. The type of substrate had a significant effect on fruiting body diameters of P. tenuiculus, and the largest mushrooms were harvested on supplemented substrate with the highest BE coinciding with the highest dry matter loss in substrates. P. tenuiculus showed a capacity to degrade sawdust, causing a decrease of 67.2–74.5% in cellulose, 80.4–85.7% in hemicellulose, and 60.6–66.2% in lignin content at the end of the cultivation cycle. The decrease in hemicellulose was relatively greater than that of cellulose and lignin on supplemented substrates. This is the first report of the cultivation of P. tenuiculus on lignocellulosic waste, and it is a promising species both for commercial production and for its potential use in the degradation of other biowastes.

Microplate assay for endo-polygalacturonase activity determination based on ruthenium red method.

Endo-polygalacturonase (endo-PGase) activity determinations generally rely on viscosity changes or reducing sugar ends produced by this activity over polygalacturonic acid. Torres and coworkers [Enzyme Microb. Technol. 48 (2011) 123-128] showed that ruthenium red (RR) is useful for endo-PGase determination. In this article, we present a high-throughput liquid-based endo-PGase assay based on the RR method and compare it with the viscosity determination method. The reduced assay uses a small volume of enzyme solution, 40 μg of polygalacturonic acid, and 45 μg of RR for each sample determination. Furthermore, we obtained an interconversion factor for RR and viscosity activities.

Mating tests in Agrocybe cylindracea sensu lato. Recognition of Agrocybe wrightii as a novel species

Mating compatibility tests among seven collections of A. cylindracea (Basidiomycetes, Agaricales) from distant geographic origins were carried out with the aim of determining if A. cylindracea includes one or more taxons from a biological perspective. Fruit body production was used to obtain spore prints, monosporic cultures and to evaluate the fructification potential of compatible crossings. Protoplast isolation, purification and regeneration were used to attempt obtaining monokaryotic isolates from 2-spored specimens. Mating tests evidenced inter-fertility of Asian, American and European strains and the inter-sterility of the Argentinean strain WT-54. These results, in addition to mitochondrial small subunit variable domains phylogeny and morphological data, lead us to consider this strain as a novel species, A. wrightii. The European, Asian and the rest of the American strains belong to A. cylindracea. The concept of A. cylindracea sensu lato includes at least two different species: A. cylindracea and A. wrightii.

Biotransformation of 1,8-cineole by solid-state fermentation of Eucalyptus waste from the essential oil industry using Pleurotus ostreatus and Favolus tenuiculus.

Biotechnological conversion of low-cost agro-industrial by-products, such as industrial waste or terpenes from the distillation of essential oils from plants into more valuable oxygenated derivatives, can be achieved by using microbial cells or enzymes. In Argentina, the essential oil industry produces several tons of waste each year that could be used as raw materials in the production of industrially relevant and value-added compounds. In this study, 1,8-cineole, one of the components remaining in the spent leaves of the Eucalyptus cinerea waste, was transformed by solid-state fermentation (SSF) using the two edible mushrooms Pleurotus ostreatus and Favolus tenuiculus. As a result, two new oxygenated derivatives of 1,8-cineole were identified: 1,3,3-trimethyl-2-oxabicyclo [2.2.2]octan-6-ol and 1,3,3-trimethyl-2-oxabicyclo [2.2.2]octan-6-one. Additionally, changes in the relative percentages of other aroma compounds present in the substrate were observed during SSF. Both fungal strains have the ability to produce aroma compounds with potential applications in the food and pharmaceutical industries.

A Comparative Study of New Aspergillus Strains for Proteolytic Enzymes Production by Solid State Fermentation

A comparative study of the proteolytic enzymes production using twelve Aspergillus strains previously unused for this purpose was performed by solid state fermentation. A semiquantitative and quantitative evaluation of proteolytic activity were carried out using crude enzymatic extracts obtained from the fermentation cultures, finding seven strains with high and intermediate level of protease activity. Biochemical, thermodynamics, and kinetics features such as optimum pH and temperature values, thermal stability, activation energy (E a), quotient energy (Q 10), K m, and V max were studied in four enzymatic extracts from the selected strains that showed the highest productivity. Additionally, these strains were evaluated by zymogram analysis obtaining protease profiles with a wide range of molecular weight for each sample. From these four strains with the highest productivity, the proteolytic extract of A. sojae ATCC 20235 was shown to be an appropriate biocatalyst for hydrolysis of casein and gelatin substrates, increasing its antioxidant activities in 35% and 125%, respectively.

Checklist of the Argentine Agaricales 7. Cortinariaceae and Entolomataceae

A checklist of species belonging to the families Cortinariaceae and Entolomataceae was made for Argentina. The list includes all species published until the year 2012. Nineteen genera and 444 species were recorded, 370 species from the family Cortinariaceae and 74 from Entolomataceae. All of them are distributed in 19 genera, the most important being Cortinarius (240 species), Galerina (51), Entoloma (39) and Inocybe (40). With the exception of Hebeloma (13 species), Gymnopilus (12) and Clitopilus (11), the rest of the 13 genera have less than 10 species each. Galeropsis , Locellina , Nolanea and Pseudogymnopilus have only one species recorded so far.