Resumo

Microbial enzymes are biocatalyst substances with a highly promising market. The endo-1-4-β-xylanase (EC 3.2.1.8), also called xylanase, has applications in various industries, such as animal feed, food, textiles, paper, production of ethanol from biomass, among others. The production of these enzymes may have its cost reduced to levels of 40-60% if derived from agro-industrial waste, particularly lignocellulosic generated during the industrial process, for example the volumes of waste created in the industries of peach-palm palmetto (Bactris gasipaes Kunth.) and sugarcane (Saccharum officinarum L.). The present work aims screening of xylanase producing fungi from different habitats of southern of Bahia State, in Brazil using simple plate assay method and submerged fermentation process. The screening of fungi capable producing xylanase was carried out using Czapeck minimal medium and xylan as sole carbon source at 30°C for up to 72 hours and stained with Congo red dye. Those plates that showed a translucent halo of hydrolysis in the medium after staining were considered positive, indicating the isolates utilization of xylan by producing xylanase enzyme. The selected fungi was used in the culture in submerged fermentation in a Czapeck minimal medium with peach-palm residue and sugarcane residue of 1% as the unique carbon sources at 30°C, 120 rpm for seven days. Among the 44 isolates tested, were pre-selected 3, which showed an index of relative enzyme (diameter discolored halo / colony diameter) greater than 2cm. The identified fungi as Trichoderma deliquescens produced the better hydrolysis halo and was used in the culture in submerged fermentation. T. deliquescens produced xylanase in presence of agroindustrial residues as sole carbon source, showed activity of 7 U/ mL and 62.8 U/mL in medium with sugarcane and peach-palm as substrate, respectively. These results demonstrate this fungi has great potential for industrial application, since they produced large quantities of xylanase compared to literature in culture conditions not yet optimized.