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Braz J Microbiol. 2011 Oct-Dec; 42(4): 1585–1597.
Published online 2011 December 1. doi:  10.1590/S1517-838220110004000046
PMCID: PMC3768745

Xylanase production by Aspergillus awamori under solid state fermentation conditions on tomato pomace

Abstract

In this work, tomato pomace, a waste abundantly available in the Mediterranean and other temperate climates agro-food industries, has been used as raw material for the production of some hydrolytic enzymes, including xylanase, exo-polygalacturonase (exo-PG), cellulase (CMCase) and α-amylase. The principal step of the process is the solid state fermentation (SSF) of this residue by Aspergillus awamori. In several laboratory experiments, maximum xylanase and exo-PG activities were measured during the first days of culture, reaching values around 100 and 80 IU/gds (international units of enzyme activity per gram of dried solid), respectively. For CMCase and α-amylase production remained almost constant along fermentation, with average values of 19 and 21.5 IU/gds, respectively. Experiments carried out in a plate-type bioreactor at lab scale showed a clear positive effect of aeration on xylanase and CMCase, while the opposite was observed for exo-PG and α-amylase. In general, xylanase was the enzyme produced in higher levels, thus the optimum conditions for the determination of the enzyme activity was characterized. The xylanase activity shows an optimum pH of 5 and an optimum temperature of 50 ºC. The enzyme is activated by Mg2+, but strongly inhibited by Hg2+ and Cu2+. The enzymatic activity remains quite high if the extract is preserved in a range of pH from 3 to 10 and a temperature between 30 ºC to 40 ºC.

Keywords: Solid state fermentation (SSF), tomato pomace, hydrolytic enzymes, plate-type bioreactor, xylanase production

Articles from Brazilian Journal of Microbiology are provided here courtesy of Elsevier