Monday, April 30, 2007

Screening of microorganisms as potential inulinase production using agroindustrial residues and optimization of culture conditions using response surface methodology

Marcio Antonio Mazutti1, Helen Treichel1, Yemiko Makino2, Maria Isabel Rodrigues2, and Francisco Maugeri Filho2. (1) Department of Food Engineering, URI - Campus de Erechim, Av. Sete de Setembro, 1621, Erechim, Brazil, (2) Department of Food Engineering, UNICAMP, CP 6121, 3083-970, Campinas, Brazil

The use of agroindustrial residues in exchange of synthetic medium is a good alternative to reduce the production costs of inulinase, since the production is improved and the downstream step will be viable technical and economically. Nevertheless, is necessary to realize screening of microorganisms that are able to over produce inulinase using agroindustrial residues. Based on these aspects, the objective of this work was to select different strains of yeasts of genus Kluyveromyces able produce inulinase employed agroindustrial residues. The results obtained on fementative screening using synthetic medium, from the 10 strain tested, pointed out that six microorganisms have potential on inulinase production. These strains were selected to carried out fermentations replace the synthetic medium for agroindustrial residues. The results of screening showed that two microorganisms were able to over produce the enzyme: the strain NCYC 587 and NRRL Y-7571. To optimize the production of inulinase by the strain NCYC 587 a fractional experimental design (25-1) and a 23 full factorial design were realized. To optimize the production by the strain NRRL Y-7571 a fractional experimental design (24-1) and a 22 full factorial design were realized. The production optimized for the two strains was approximately of 720 U mL-1. The composition optimized (for both strains) of agroindustrial residues were (g L-1): molasses 90.0, CSL 45.0 and YE 4.0.  The temperature optimal was 30C for both strains and pH optimal was 3.5 for strain NCYC 587 and 5.5 for strain NRRL Y-7571. The production was improved seven times employed agroindustrial residues.