Poster Presentation 1B-37

High Yield Bacillus subtilis Protease Production by Solid-state Fermentation using Soybean Waste

V.F. Soares,¹ L.R. Castilho,² E.P.S. Bon,¹ and D.M.G Freire³

¹ Laboratório de Tecnologia Enzimática – D

epto. de Bioquímica – IQ – UFRJ

² Programa de Engenharia Química – COPPE – UFRJ

³ Laboratório de Biotecnologia Microbiana – Depto. de Bioquímica – IQ – UFRJ

E-mail: freire@iq.ufrj.br

A protease producer strain of Bacillus subtillis, isolated from the guts of the larvae Brucludae pachymerus, a parasite of the babassu coconut, was comparatively cultivated in submerged (SmF) and solid state fermentations (SSF) aiming at the production of a high yield, low cost protease preparation. In optimised submerged fermentation the microorganism was cultivated using a derepressive growth medium containing peptone 1%, yeast extract 0.5 % and soy oil 0.1 % (w/v) and incubated at 37°C, 200 rpm for 24 hours. Protease concentration in the culture supernatant, using azocasein as substrate, reached 12 U/mL within 10 hours of incubation. This same culture, incubated for 7 hours was used as inoculum in solid-state fermentation having as substrate the agricultural residues soybean cake or babassu cake. The tray reactors process was conducted at 30^oC and substrate moisture content was kept at 67 % w/w. The maximum levels of protease in the extracts of the solid-state fermentation, utilizing soybean cake, reached 120 U/mL (960 U/g of substrate). These values were ten fold higher than that observed in the supernatants of the SmF process. Moreover the productivity figures for the SSF process, of 15.4 U/g.h or 1.93 U/mL.h, were 45% higher in comparison to the submerged fermentation data, around 1.33 U/mL.h.