Xylanolytic complex from Aspergillus giganteus: production and characterization

Abstract

An Aspergillus giganteus strain was isolated as an excellent producer of xylanase associated with low levels of cellulase. Optimal xylanase production was obtained in liquid Vogel medium containing xylan as carbon source, pH 6.5 to 7.0, at 25 degrees C and under shaking at 120 rpm during 84 h. Among the several carbon sources tested, higher xylanase production was verified in xylan, xylose, sugar-cane bagasse, wheat bran and corn cob cultures, respectively. Optimal conditions for activity determination were 50 degrees C and pH 6.0. The xylanolytic complex of A. giganteus showed low thermal stability with T(50) of 2 h, 13 min and 1 min when it was incubated at 40, 50 and 60 degrees C, respectively, and high stability from pH 4.5 to 10.5, with the best interval between 7.0 to 7.5. This broad range of stability in alkali pH indicates a potential applicability in some industrial processes, which require such condition. Xylanolytic activity of A. giganteus was totally inhibited by Hg(+2), Cu(+2) and SDS at 10 mM. The analysis of the products from the oat spelts xylan hydrolysis through thin-layer chromatography indicated endoxylanase activity, lack of debranching enzymes and beta-xylosidase activity in assay conditions.

Purification and characterization studies of a thermostable β-xylanase from Aspergillus awamori

“…Nevertheless, an evident activity decrease was observed above 60°C. These findings are in agreement with those reported by Shah and Madamwar [55] and Coelho and Carmona [16], who reported that the optimum temperature was 50°C and the optimum pH was 5.3 and 6.0, respectively, for Aspergillus foetidus and Aspergillus giganteus xylanases. According to Table 3, the optimum temperature and pH value of xylanases from Aspergillus species ranges from 42 to 55°C and 4.0 to 6.0, respectively.…”

“…The observed protective effect of L-cysteine could be related to the presence of a reducing Fig. 4 Effect of pH and temperature on xylanase activity from the culture filtrate ( ) and on the PXII-1 xylanase preparation ( ) The half-lives for several fungi xylanases at 50°C have been reported as 1 h for Aspergillus foetidus [55], 13 min for A. giganteus [16], and 4 h for A. awamori NRRL 3112 [42]. Concerning stability at 55°C, xylanase II purified from A. caespitosus was fully stable for up to 90 min [54].…”

Optimization of fibrolytic enzyme production by Aspergillus japonicus C03 with potential application in ruminant feed and their effects on tropical forages hydrolysis

“…These results are in accordance to with results obtained by Coelho and Carmona [34], which obtained xylanase production 43% higher under static conditions and it was observed that xylanase activities peaks in 5 and 3.5 days cultures under static and shaking conditions, respectively, with xylan as carbon source by A. giganteus. Seyis and Aksoz [35] reported that T. harzianum 1073 D3 produced the maximum level of xylanase after 13 days with xylan as the only carbon source, under static conditions.…”

Partial purification and properties of cellulase-free alkaline xylanase produced by Rhizopus stolonifer in solid-state fermentation

“…Heck et al (2002) reported 5.19 U/mg protein for xylanase of a strain of Bacillus subtilis; Damaso et al (2002), using Thermomyces lanuginosus (IOC-4145), obtained 85 U/mg protein for the xylanase activity in a filtered culture. Coelho and Carmona (2003) reported 107.43 U/mg protein for xylanase, using A. giganteus. The specific activity of xylanase determined in our work was lower than the range cited in the literature; however, no cellulase activity was found in the fraction P-II, using cellulose microcrystalline Sigma 1% (w/v).…”