Use of lignocellulose biomass for endoxylanase production by Streptomyces termitum.

Actinobacteria isolates from Brazilian Cerrado soil were evaluated for their ability to produce enzymes of the cellulolytic and xylanolytic complex using lignocellulose residual biomass. Preliminary semiquantitative tests, made in Petri plates containing carboxymethylcellulose and beechwood xylan, indicated 11 potential species producing enzymes, all belonging to the genus Streptomyces. The species were subsequently grown in pure substrates in submerged fermentation and analyzed for the production of enzymes endoglucanase, ß-glucosidase, endoxylanase, and ß-xylosidase. The best results were obtained for endoxylanase enzyme production with Streptomyces termitum(UFLA CES 93). The strain was grown on lignocellulose biomass (bagasse, straw sugarcane, and cocoa pod husk) that was used in natura or acid pretreated. The medium containing sugarcane bagasse in natura favored the production of the endoxylanase that was subsequently optimized through an experimental model. The highest enzyme production 0.387 U mL-1, (25.8 times higher), compared to the lowest value obtained in one of the trials, was observed when combining 2.75% sugar cane bagasse and 1.0 g L-1 of yeast extract to the alkaline medium (pH 9.7). This is the first study using S. termitum as a producer of endoxylanase.

Biological detoxification of different hemicellulosic hydrolysates using Issatchenkia occidentalis CCTCC M 206097 yeast.

This work had as its main objective to contribute to the development of a biological detoxification of hemicellulose hydrolysates obtained from different biomass plants using Issatchenkia occidentalis CCTCC M 206097 yeast. Tests with hemicellulosic hydrolysate of sugarcane bagasse in different concentrations were carried out to evaluate the influence of the hydrolysate concentration on the inhibitory compounds removal from the sugarcane bagasse hydrolysate, without reduction of sugar concentration. The highest reduction values of inhibitors concentration and less sugar losses were observed when the fivefold concentrated hydrolysate was treated by the evaluated yeast. In these experiments it was found that the high sugar concentrations favored lower sugar consumption by the yeast. The highest concentration reduction of syringaldehyde (66.67%), ferulic acid (73.33%), furfural (62%), and 5-HMF (85%) was observed when the concentrated hydrolysate was detoxified by using this yeast strain after 24 h of experimentation. The results obtained in this work showed the potential of the yeast Issatchenkia occidentalis CCTCC M 206097 as detoxification agent of hemicellulosic hydrolysate of different biomass plants.

Fracionamento químico da matéria orgânica e características de ácidos húmicos de solos com horizonte a antrópico da amazônia (Terra Preta) / Chemical fractionation of organic matter and humic acid characteristic in anthropogenic dark earth soils of brazilian amazonic region

Os solos da Amazônia que possuem horizonte A antrópico (Au) apresentam elevada fertilidade natural geralmente atribuída ao teor elevado de matéria orgânica e à sua elevada reatividade. Neste estudo foram quantificadas as substâncias húmicas e caracterizados os ácidos húmicos (AH) extraídos da camada 0-20 cm de solos com horizonte Au do estado do Amazonas (Terra Preta de índio) sob floresta e cultivo agrícola. Também foram investigadas amostras de solos adjacentes sem o horizonte antrópico. A caracterização dos AH foi realizada através de análise termogravimétrica, análise da composição elementar e quantificação dos grupos funcionais (total, carboxílica e fenólica). Os horizontes A de solos antropogênicos apresentaram maior teor de carbono total, comparados aos de solos adjacentes. Entre as frações húmicas, a mais abundante foi a humina. A fração de ácidos húmicos (AH) foi a dominante das frações alcalino-solúveis nos solos estudados. Os AH dos solos antropogênicos tanto sob floresta como sob cultivo agrícola apresentaram maior grau de humificação quando comparados aos AH dos solos sem o horizonte Au. O cultivo agrícola também teve efeito na estabilidade e reatividade dos AH nos solos antropogênicos.

Amazonian dark earth soils that have anthropogenic A horizon (Au) present high natural fertility usually attributed to their high organic matter content and to their higher reactivity. In this study humic substances were quantified and the humic acids (HA) extracted from the 0-20 cm layer of Amazonian dark earth soils (Terra Preta do índio) under forest and agricultural use were characterized. Adjacent soils with no Au horizon were also investigated. The HA were characterized through the thermogravimetric analysis, elemental composition analysis and characterization of functional groups (total, carboxylic, and phenolic). The A horizon of the anthropogenic soils presented higher total carbon level compared to adjacent soils. Among the humic fractions, the humin was the most abundant. The humic acid fraction (HA) was the dominant among the alkaline soluble fractions. The humic acids of the anthropogenic soils, both under forest and cultivation, showed higher humification degree compared to the non-anthropogenic soils. The agricultural cultivation affected the humic acids stability and reactivity in the anthropogenic soils.