title: 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 Mg(2+), but strongly inhibited by Hg(2+) and Cu(2+). 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.
authors.affiliation: Laboratório de Bioquímica e Microbiologia Aplicada, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista , São José do Rio Preto, SP , Brasil.
authors.forename: Marcelo A
authors.initials: MA
authors.lastname: Umsza-Guez
authors.forename: Ana B
authors.initials: AB
authors.lastname: Díaz
authors.forename: Ignacio
authors.initials: I
authors.lastname: de Ory
authors.forename: Ana
authors.initials: A
authors.lastname: Blandino
authors.forename: Eleni
authors.initials: E
authors.lastname: Gomes
authors.forename: Ildefonso
authors.initials: I
authors.lastname: Caro
keywords: Solid state fermentation (SSF); hydrolytic enzymes; plate-type bioreactor; tomato pomace; xylanase production
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