Estudo da produção de celulases por fermentação semisólida em bagaço de caju (Anarcadium orcidentalle Lineu) utilizando o microorganismo Trichoderma sp.

Abstract

Despite the widespread use of cellulases, their high cost has made some processes become expensive. The cashew apple is a lignocellulosic material which has an estimated production in Brazil around 1.8 million tons/year concentrating primarily in the Northeast and with industrial use of only 15% of its total. Within this context, this work aimed to study the production of cellulase by semisolid fermentation of cashew apple waste using microorganism Trichoderma sp. The first step was to perform a physical-chemical characterization of cashew bagasse and characterization of the moisture adsorption isotherm of bagasse at a temperature of 30°C. Then it was studied the semisolid fermentation of the cashew bagasse for production of the enzyme, using the design methodology of factorial type 22 with three replications at the central point to evaluate the influence of the dependent variables, initial moisture and concentration of nitrogen source on enzyme activity. The fermentation process was developed for the cashew bagasse, washed and unwashed, using the microorganism Trichoderma sp. with a concentration of 107 spores/g at a temperature of 30°C with the initial moisture content ranging from 45, 55 and 65% in wet basis, nitrogen source concentration ranging from 0.50, 0.75 and 1.00% and samples were collected throughout the process in order to analyze the pH, moisture, reducing sugars and enzyme activity, expressed in carboxymethylcellulase until a time of 73 hours. The physical-chemical characterization showed that the cashew bagasse is a suitable substrate for the production process of the enzyme cellulase for presenting favorable conditions for the fermentation process with an acidic pFI optimal for enzyme production in semisolid fermentation with fungi (4.84 for the washed bagasse and 3.94 for the unwashed bagasse) and a carbon source represented by reducing sugars (0.31% for the washed bagasse and 25.53% for the unwashed bagasse) and cellulose (22.75% for the washed bagasse and 21.32% for the unwashed bagasse). The experimental design showed that the fermentation process was reproductive for both washed bagasse as for the unwashed because they had coefficients of variation less than 10%o for replications at the central point. The major enzyme activity obtained for the washed bagasse was 1.173 U/g in 42 hours of fermentation when it was used 45% of initial moisture and 1.00% of added nitrogen source and the unwashed bagasse, the highest activity enzyme was 1.896 U/g in 18 hours of fermentation when it was used 55% of initial moisture and 0.75% of added nitrogen source. The major productivity obtained for the washed and unwashed bagasse was when used 55% of initial moisture and 0.75% of added nitrogen source with 0.064 U/g.h and 0.105 U/g.h, respectively.