Industrial Crops and Products 42 (2013) 236–242 Contents lists available at SciVerse ScienceDirect Industrial Crops and Products journa l h o me pag e: www.elsevier.com/locate/indcrop Effect of initial moisture content on two Amazon rainforest Aspergillus strains cultivated on agro-industrial residues: Biomass-degrading enzymes production and characterization Priscila da Silva Delabona a,b , Rosangela Donizete Perpetua Buzon Pirota a,b , Carla Aloia Codima a,b , Célia Regina Tremacoldi c , André Rodrigues d , Cristiane Sanchez Farinas a,∗ a Embrapa Instrumentac ¸ ão, Rua XV de Novembro 1452, 13560-970 São Carlos, São Paulo, Brazil b Universidade Federal de São Carlos, 13565-905 São Carlos, São Paulo, Brazil c Embrapa Amazônia Oriental, Trav. s/n o . Caixa Postal 48, Belém, Pará, Brazil d Universidade Estadual de Santa Cruz, 45662-900 Ilhéus, Bahia, Brazil a r t i c l e i n f o Article history: Received 9 February 2012 Received in revised form 27 May 2012 Accepted 30 May 2012 Keywords: Aspergillus Cellulases Xylanases Enzymes Agro-industrial residues Solid-state fermentation a b s t r a c t Production of biomass-degrading enzymes using inexpensive and readily available agricultural residues as substrates for solid-state fermentation (SSF) can contribute to a broader application of enzymes for the conversion of biomass into biofuels and chemicals. Among the operational parameters that affect SSF process efficiency, moisture content is one of the most important. This work evaluates the effect of initial moisture content on two Aspergillus strains (Aspergillus niger P47C3 and Aspergillus fumigatus P40M2), isolated from the Amazon rainforest and grown under SSF. Analyses were made of the biomass- degrading enzymes produced using different agro-industrial residues as carbon sources (wheat bran, sugar cane bagasse, soybean bran, and orange bagasse). The enzymatic complex produced by a selected strain of A. fumigatus was characterized in terms of optimum pH and temperature, and thermal stability. The most effective carbon sources for multienzyme production during Aspergillus cultivation were wheat and soybean bran, as well as a 1:1 mixture of sugar cane bagasse and wheat bran. Much higher activity values were achieved for -glucosidase (105.8 IU/g) and xylanase (1055.6 IU/g) when wheat bran with 50% initial moisture content was used as substrate. Under this condition, endoglucanase and total cellu- lase activity values were 56.6 IU/g and 5.0 FPU/g, respectively. Characterization of the crude enzymatic complex showed that the A. fumigatus P40M2 enzymes were active in the acidic pH range, with maximal activities at the range of 50–65 ◦ C, demonstrating the potential of the organism for the production of acidophilic and thermophilic biomass-degrading enzymes. © 2012 Elsevier B.V. All rights reserved. 1. Introduction The conversion of lignocellulosic materials into biofuels and other chemicals can be achieved using a multienzyme system composed predominantly of cellulases and xylanases, acting in synergy. However, the major bottleneck for a broader application of enzymes in the process of biomass conversion is their high cost. Cellulolytic enzyme production under solid-state fermentation (SSF), using inexpensive and easily available agricultural residues as substrates, can contribute to cost reduction (Sukumaran et al., 2009). In addition, growth of filamentous fungi using SSF is advan- tageous since the solid medium simulates the natural habitat of these organisms (Singhania et al., 2009). This benefit is extended to the production of enzymes, with SSF yielding greater productivity ∗ Corresponding author. Tel.: +55 16 2107 2908; fax: +55 16 2107 2902. E-mail address: cristiane@cnpdia.embrapa.br (C.S. Farinas). when compared to submerged fermentation (SmF) (Raghavarao et al., 2003). In SSF processes, the water content is one of the most important operational parameters affecting process efficiency. If the moisture content is too high, the void spaces in the solids are filled with water, resulting in oxygen limitation. At the other extreme, if the moisture content is too low, microorganism growth will be hindered (Raghavarao et al., 2003). Consequently, identi- fication of the optimal moisture content for each solid substrate is crucial to promote favorable growing conditions and maximize the production of metabolites. The effect of the initial moisture content of the substrate on the production of biomass-degrading enzymes by SSF has been described in the literature. Singhania et al. (2007) found that higher initial moisture levels had a negative effect on cellulase production by Trichoderma reesei grown on wheat bran under SSF. Mamma et al. (2008) evaluated enzyme production in SSF using orange peel as substrate and the fungus Aspergillus niger, and were able to significantly increase enzyme activities after optimizing 0926-6690/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.indcrop.2012.05.035