Estudo com Xilanase de Thermomyces lanuginosus na produção de Xilooligossacarídeos a partir de sorgo biomassa e seu efeito prebiótico.

Abstract

Endoxylanase is one of the enzymes of the xylanolytic complex produced by the fungus Thermomyces lanuginosus with great industrial interest, mainly due to its stability at high temperatures and its wide biotechnological application. Thus, the present work aimed to investigate the production of xylooligosaccharides from sorghum biomass pre-treated with the free and immobilized endoxylanase of T. lanuginosus as well as to test its prebiotic action in culture with the probiotic Lactobacillus acidophilus. Initially, the extracellular endoxylanase obtained from the liquid culture of T. lanuginosus was purified by chromatographic columns and immobilized with sodium alginate, forming spheres through the drip method in a 300 mM calcium chloride solution, which obtained 78.5 % of immobilization income. The immobilized enzyme exhibited reuse for 11 cycles, with a residual catalytic activity of 30 %. The thermal stability for the free form of the enzyme was 100 % activity at temperatures of 65 ºC and 75 ºC for 5 hours, and 3 hours at 85 ºC with a residual activity of 70 %. However, the immobilized form was 100 % stable for 5 hours at 65 °C, and a half-life of 5 hours at 85°C. Both forms showed excellent stability in the range of pH 4.0 to 9.0, however, at pH 9.0 the enzyme in its free form obtained 66% of residual activity after 96 hours of incubation. Free endoxylanase immobilized in calcium alginate was used to hydrolyze the xylan obtained from sorghum biomass previously treated with 5 % hydrogen peroxide and 2 % NaOH with a yield of 11.7 % of xylan. The high performance liquid chromatography (HPLC) analysis of xylan hydrolysis products by free and immobilized endoxylanase after 1 hour of enzymatic reaction showed 6.778 g/L and 5.076 g/L of xylooligosaccharides, respectively. Among the xylooligosaccharides found were xylobiose, xylotriose, xylotetraose, xylopentose and xylohexaose, with the highest concentrations of xylotetraose and xylopentaose. The prebiotic effect of the produced XOs was verified by their consumption as a carbon source for the growth of the Lactobacillus acidophilus bacteria. Therefore, the endoxylanase enzyme from the fungus T. lanuginosus is promising in the production of XOS with prebiotic action with a good response when immobilized, thus being an alternative for employability in more sustainable biotechnological industrial processes.