RESUMO
Abstract The Brazilian savanna, known as the Cerrado, is a biome with a high degree of endemism, with the potential to house many microorganisms suitable for biotechnological exploitation, especially fungi. The Cerrado soil, which is usually acidic, is a favorable environment for the growth of fungi capable of degrading lignocellulosic materials. The aim of the present study was to isolate cellulolytic filamentous fungi native to the Cerrado. Samples of soil and leaf litter were collected in three points of Cerrado State Park, located in the South of Brazil, during the rainy season in September 2014. Samples were stored in sterile plastic bags, transported at room temperature and kept at 4 ºC for three days. Filamentous fungi were isolated by successive inoculations in PDA (maintained at 30 ºC). Cellulase activity was tested in CMC (carboxymethyl cellulose) medium and lipase activity was assessed in medium containing phenol red and tween 20 (incubated at 37 °C), and in medium supplemented with Rhodamine B (kept at 30 °C). We isolated a total of 28 strains, 25 produced cellulase, detected with lugol in strains grown in CMC medium. The isolates were identified morphologically (color, form of growth) and by sequencing of the 18S rRNA region, with both techniques producing congruent results. One strain of Colletotrichum boninense and one strain of Trichoderma sp., both isolated from soil samples, presented the highest cellulolytic activity. All strains exhibited lipolytic activity, with enzyme production and activity influenced by temperature. The present study revealed new strains of known filamentous fungi that can be applied in biomass degradation. These strains are suitable for optimization of culture conditions, which could lead to the economic feasibility of the process. Rev. Biol. Trop. 66(1): 237-245. Epub 2018 March 01.
Resumen La sabana brasileña conocida como Cerrado, es un bioma con alto grado de endemismo con el potencial de albergar muchos microorganismos de alto interés biotecnológico. Los hongos producen muchas enzimas que se aplican ampliamente en procesos industriales. El suelo del Cerrado, que suele ser ácido, es un ambiente favorable para el crecimiento de hongos capaces de degradar materiales lignocelulósicos. El objetivo del presente estudio fue aislar los hongos celulolíticos filamentosos nativos del Cerrado. Muestras de suelo y de hojarasca fueron recolectadas en el Parque Estatal del Cerrado, ubicado en el sur de Brasil. De 28 cepas aisladas, 25 produjeron celulasa que fue detectada con lugol. Las cepas fueron cultivadas en medio CMC (carboximetilcelulosa). Los aislados fueron identificados morfológicamente (color, forma de crecimiento) y por secuenciación de la región 18S rRNA, produciendo resultados congruentes. Una cepa de Colletotrichum boninense y una cepa de Trichoderma sp., ambas aisladas de muestras de suelo, presentaron la mayor actividad celulolítica. Todas las cepas mostraron actividad lipolítica, la producción y la actividad se vieron influidos por la temperatura. El presente estudio revela nuevas cepas de hongos filamentosos conocidos con potencial de aplicación en la degradación de la biomasa, sin embargo, la optimización de las condiciones de cultivo es necesaria para lograr la viabilidad económica.