Cellulolytic and lipolytic fungi isolated from soil and leaf litter samples from the Cerrado (Brazilian Savanna) / Hongos celulolíticos y lipolíticos aislados a partir de muestras de suelo y de hojarasca del Cerrado (Sabana brasileña)

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.

Production of antioxidant xylooligosaccharides from lignocellulosic materials using Bacillus amyloliquifaciens NRRL B-14393 xylanase.

The present study aimed to evaluate the enzymatic production of XOS, antioxidant activities together with total phenolic contents from different lignocellulosic materials and birchwoodxylan using both crude and pure forms of Bacillus amyloliquifaciens NRRL B-14393 xylanase respectively. The mode of action of the pure xylanase was studied by HPLC and the end products analysis of birchwoodxylan revealed that xylose, xylobiose and xylotriose were the only end products. The resulted XOS mixture exhibited potent antioxidant activity of 87.36 % and high total phenolic content of 182.88 mg GAE/ liter of extract. XOS were obtained from different alkali pretreated agricultural residues by the crude xylanase action with a yield in a range from 54.4% to85.5%.Maximum scavenging abilities and total phenolic contents of XOS mixtures of all the tested materials were determined. XOS mixtures of orange and mango peels revealed relatively higher antioxidant activities (96% and 76.84%, respectively) and total phenolic acid contents (156.32 and 133.74 mg GAE/ liter of extract, respectively) compared to the other XOS mixtures. In conclusion, Bacillus amyloliquifaciens NRRL B-14393 xylanase could be a promising source for production of XOS with high phenolic contents and antioxidant activities.

Xylooligosaccharides: an economical prebiotic from agroresidues and their health benefits.

Oligosaccharides and dietary fibres are non-digestible food ingredients that preferentially stimulate the growth of prebiotic Bifidobacterium and other lactic acid bacteria in the gastro-intestinal tract. Xylooligosaccharides (XOS) provide a plethora of health benefits and can be incorporated into several functional foods. In the recent times, there has been an over emphasis on the microbial conversion of agroresidues into various value added products. Xylan, the major hemicellulosic component of lignocellulosic materials (LCMs), represents an important structural component of plant biomass in agricultural residues and could be a potent bioresource for XOS. On an industrial scale, XOS can be produced by chemical, enzymatic or chemo-enzymatic hydrolysis of LCMs. Chemical methods generate XOS with a broad degree of polymerization (DP), while enzymatic processes will be beneficial for the manufacture of food grade and pharmaceutically important XOS. Xylooligomers exert several health benefits, and therefore, have been considered to provide relief from several ailments. This review provides a brief on production, purification and structural characterization of XOS and their health benefits.

Propriedades físico-mecânicas de painéis aglomerados madeira-bambu / Physical mechanical properties of wood-bamboo particleboard

Foram avaliadas as propriedades físico-mecânicas de painéis aglomerados produzidos com diferentes proporções de madeira (Eucalyptus grandis) e bambu (Bambusa vulgaris). Os painéis foram produzidos utilizando o adesivo ureia-formaldeído com a adição de 0, 25, 50, 75 e 100% de bambu. Para cada tratamento, determinaram-se as propriedades físicas (massa específica; teor de umidade; absorção de água e inchamento em espessura após 2 e 24 horas de imersão em água) e mecânicas (flexão estática; ligação interna; e arrancamento de parafusos). Os resultados obtidos indicaram que o acréscimo das partículas de bambu proporcionou uma redução significativa na qualidade dos painéis para os parâmetros avaliados, apresentando uma maior absorção de água e uma menor resistência à flexão estática e ao arrancamento de parafuso.

It was evaluated the physical and mechanical properties of particleboard produced with different proportions of wood (Eucalyptus grandis) and bamboo (Bambusa vulgaris). The boards were produced using urea-formaldehyde adhesive with the addition of 0, 25, 50, 75 and 100% of bamboo. For each treatment were determined physical properties (specific gravity, moisture content, water absorption and thickness swelling after 2 and 24 hours water immersion) and mechanical properties (static bending, internal bond and screw withdrawal). The results indicated that the addition of particles of bamboo provided a significant reduction in the quality of panels for most parameters, showing higher water absorption and a lower resistance to static bending and screw withdrawal.

Influence of novel lignocellulosic residues in a biobed biopurification system on the degradation of pesticides applied in repeatedly high doses

Background: The biobed is a simple biopurification system used to prevent the point-source pesticide contamination that occurs at farm level. The typical composition of the biomixture used in this system is soil, peat and straw in volumetric proportions of 1:1:2. The principal component is straw due to its positive effects on biological activity and thus pesticide degradation. However, access to straw can be limited in some regions, so it must be replaced by other more readily available lignocellulosic residues. Results: Therefore, two alternate lignocellulosic materials (barley husks and pine sawdust) were evaluated as partial substitutes for straw. The degradation of a repeatedly applied mixture of six pesticides by these alternates was assessed. The microbial respiration and fluorescein diacetate (FDA) hydrolysis activity were also assessed. The results showed that the highest degradation efficiency was found in mixtures containing straw and barley husks. Each biomixtures tested achieved a high degradation (50 to 90%) of all the pesticides used except iprodione. Repeated applications of pesticides resulted in a slowing of the degradation rate of all pesticide types in all biomixtures. FDA activity and microbial respiration were higher in the biomixtures containing barley husks and straw compared to the mixture with pine sawdust, a result consistent with the pesticide degradations observed. Conclusions: This paper demonstrates that the straw in the traditional biomixture can be partially replaced by other lignocellulosic materials to efficiently degrade a mixture of pesticides, even when the pesticides are added in successive applications and high concentrations.