Potencial biotecnológico de fungos filamentosos celulolíticos isolados de restinga

Abstract

The objectives of this study were to isolate, quantify, identify and assess the cellulolytic ability of cellulolytic fungi of sandy sediment in the thicket of Guaibim sandbank in the town of Valença, Bahia. Were collected monthly sediment, in a total of four collections, these collections were obtained two samples of different points. To isolate was taken to the serial dilution technique and the inoculum was transferred to dilution plates with selective medium mineral salts 1% (w/v) microcrystalline cellulose. The plates were incubated at 28°C for 10 days. For morphological identification at genus level was performed microculture technique. The isolates were tested for potential cellulolytic submerged in filter paper containing as the sole carbon source and mineral salts medium for subsequent detection of whole cellulase activity (FPase) and Endoglicanase (CMCase), by quantification of reducing sugars. The isolated promising was tested for production of cellulase using sugar cane bagasse in natura as the carbon source and corn steep as nitrogen source such, according to the factorial design CCRD 23 array. The enzyme production was optimized and validated according to the analyzes provided by the program STATSOFT ® 7.0 and the enzyme extract was characterized as the optimal temperature and pH. 50 cellulolytic fungi were isolated from the thicket of Guaibim sandbank. Most identified fungi belong to the phylum Ascomycota, and the genus Penicillium, Aspergillus and Trichoderma, more frequent. About 44% of the isolates tested showed enzyme activity FPase greater than 100 U.L-1 and 32% showed CMCase activity greater than 500 U.L-1. The most promising isolate was Aspergillus sp. IS-17 which produced 880 U.L-1 FPase activity and 5016 U.L-1 CMCase activity in submerged fermentation containing filter paper as the sole carbon source, and therefore selected for fermentation using sugar cane bagasse in natura. The isolate tested produced satisfactory levels of enzymatic activity, reaching 3518 U.L-1 after three days of fermentation under optimized conditions of enzyme production. Biochemical characterization revealed that the endoglucanase enzyme produced by Aspergillus sp. IS-17 has optimum activity at 70 ° C, pH 6.0 using sodium citrate as buffer. The isolates of the thicket of Guaibim showed a high biotechnological potential and may be used in various industrial processes, however, new studies should be conducted in order to detail the action of the enzyme, determine the economic viability and composition of waste used.