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

• Published in: Brazilian journal of microbiology Vol. 42; no. 4; pp. 1585 - 1597
• Main Authors: Umsza-Guez, Marcelo A, Díaz, Ana B, de Ory, Ignacio, Blandino, Ana, Gomes, Eleni, Caro, Ildefonso
• Format: Journal Article
• Language: English; Portuguese
• Published: Brazil Springer Nature B.V 01.10.2011; Sociedade Brasileira de Microbiologia
• Subjects: Agricultural biotechnology; Fermentation; Fungi; Membrane reactors; MICROBIOLOGY; Tomatoes; Brazil; tomato pomace; xylanase production; Solid state fermentation (SSF); hydrolytic enzymes; plate-type bioreactor
• ISSN: 1517-8382; 1678-4405; 1678-4405
• DOI: 10.1590/S1517-83822011000400046

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.