Biogeografía de especies de Fusarium en el litoral mediterráneo de España

El trabajo presentado estudia la presencia de Fusarium oxysporum, F.solani(sensulato), F. equiseti y F.acuminatum en puntos del litoral de Almería, Alicante, Gerona e Islas Baleares (Menorca, Ibiza, Espalmador). Se analizaron tanto arenas de las playas (zonas intermareal y supramareal) como fondos marino situados a 27,9 y 7,2 metros de profundidad en Almería y a 10 m de profundidad en las Islas Baleares. Exceptuando el litoral de Gerona, en el resto de los enclaves se presentaron varias especies de Fusarium que se aislaron de las arenas de las playas, confirmando así resultados obtenidos con anterioridad. Lo más novedoso fue encontrar especies de Fusarium a diferentes profundidades marinas. En Almería F.oxysporum y F.equisti se aislaron a 27,9 y7,2 m profundidad. F. acuminatum se aisló de la muetra recogida a 27m de profundidad. En las islas Baleares, a10m de profundidad, se aislaron F. oxysporum, F. solani (sensulato), F.equiseti y F.acuminatum. El efecto antrópico, el comportamiento como "airborne" o los arrastres de aguas por las ramblas y torrentes podría explicar la presencia de estas especies en los hábitats mencionados. La permanencia de estas especies en los hábitats mencionados, especialmente en la zona intermareal de las playas y en los fondos marinos donde soportan elevadas presiones osmóticas por la alta salinidad del agua del mar Mediterráneo, permitirá estudios específicos sobre el comportamiento de estos hongos en medios muy salinos. Otros hongos aislados de arenas de playa y fondos marinos fueron: Acremonium, Alternaria, Aspergillus, Cladosporium, Dreschlera, Gliocladium Humicola, Penicillium, Phialophora, Rhizopus, Stemphylium, Trichoderma, Trichocladium y Ulocladium. Muchos de ellos fueron aislados del fondo marino, testimoniando así que estos hábitats no son exclusivos de Fusarium.

In vitro evaluation of commercial fibrolytic enzymes for improving the nutritive value of low-quality forages.

The aim of this work was to assess the effects of four doses of three commercial fibrolytic enzymes on ruminal fermentation of rice straw, maize stover and Pennisetum purpureum clon Cuba CT115 hay in batch cultures of ruminal micro-organisms from sheep. One enzyme was produced by Penicillium funiculosum (PEN) and two were from Trichoderma longibrachiatum (TL1 and TL2). Each liquid enzyme was diluted 200 (D1), 100 (D2), 50 (D3) and 10 (D4) - fold and applied to each substrate in quadruplicate over time and incubated for 120 h in rumen fluid. The D4 dose of each enzyme increased (P<0.05) the fractional rate of gas production and organic matter effective degradability for all substrates, and TL2 had similar effects when applied at D3. In 9 h incubations, PEN at D4, TL1 at all tested doses, and TL2 at D2, D3 and D4 increased (P<0.05) volatile fatty acid production and dry matter degradability for all substrates. The commercial enzymes tested were effective at increasing in vitro ruminal fermentation of low-quality forages, although effective doses varied with the enzyme.

Treatment of tropical forages with exogenous fibrolytiic enzymes: effects on chemical composition and in vitro rumen fermentation

The effects of three treatments of fibrolytic enzymes (cellulase from Trichoderma longibrachiatum (CEL), xylanase from rumen micro-organisms (XYL) and a 1:1 mixture of CEL and XYL (MIX) on the in vitro fermentation of two samples of Pennisetum clandestinum (P1 and P2), two samples of Dichanthium aristatum (D1 and D2) and one sample of each Acacia decurrens and Acacia mangium (A1 and A2) were investigated. The first experiment compared the effects of two methods of applying the enzymes to forages, either at the time of incubation or 24 h before, on the in vitro gas production. In general, the 24 h pre-treatment resulted in higher values of gas production rate, and this application method was chosen for a second study investigating the effects of enzymes on chemical composition and in vitro fermentation of forages. The pre-treatment with CEL for 24 h reduced (p < 0.05) the content of neutral detergent fibre (NDF) of P1, P2, D1 and D2, and that of MIX reduced the NDF content of P1 and D1, but XYL had no effect on any forage. The CEL treatment increased (p < 0.05) total volatile fatty acid (VFA) production for all forages (ranging from 8.6% to 22.7%), but in general, no effects of MIX and XYL were observed. For both P. clandestinum samples, CEL treatment reduced (p < 0.05) the molar proportion of acetate and increased (p < 0.05) that of butyrate, but only subtle changes in VFA profile were observed for the rest of forages. Under the conditions of the present experiment, the treatment of tropical forages with CEL stimulated their in vitro ruminal fermentation, but XYL did not produce any positive effect. These results showed clearly that effectiveness of enzymes varied with the incubated forage and further study is warranted to investigate specific, optimal enzyme-substrate combinations.