Sunday, April 29, 2007

Penicillium simplicissimum: morphology and lipase production in solid-state fermentation and in submerged fermentation

Melissa L. E. Gutarra1, Mateus G. Godoy1, Iamê A. Guedes2, Ulysses Lins2, Leda R. Castilho3, Denise M. G. Freire1, and Jaqueline Do Nascimento Silva3. (1) Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil, (2) Departamento de Microbiologia Geral, Instituto de Microbiologia Prof. Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil, (3) Programa de Engenharia Química, COPPE, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil

Several advantages of solid state fermentation (SSF) over submerged fermentation (SmF) have been stressed in previous studies, including higher productivities and enzymes with higher thermal stability than in SmF. Although growth phenotypes and physiological characteristics can, in principle, explain the advantages of SSF over SmF, few studies on this subject are available. In this work, we evaluated lipase production by Penicillium simplicissimum in SSF and SmF, and investigated its physiological and morphological behavior in both systems. High maximum lipase and specific activities (80U/g of initial dry cake and 4.5 U/mg of protein) were obtained in SSF with babassu supplemented with 6.25 % sugar cane molasses or 1% olive oil, both with similar growth and lipase production profiles. In SmF, P. simplicissimum with synthetic and babassu-based media, supplemented with either sugar cane molasses or olive oil, presented specific activities 6-fold lower than in SSF. Furthermore, in SmF catabolic repression occurred for molasses supplementations as low as 1%, whereas in SSF it was not observed with 6.25% molasses. In SSF, the fungus was able to colonize and penetrate the substrate layer, growing on the grain surfaces with abundant spore production. In SmF with synthetic medium, the fungus formed densely interwoven mycelial masses, without spore production. In SmF with babassu cake, it grew as free mycelia and on the grain surfaces, with moderate spore production. Our data indicate that, in SSF, the low availability of nutrients and water dictates fungal morphology and physiology, being responsible for high spore and lipase production.