Sunday, April 29, 2007
2-46

Lipase production in solid state fermentation monitoring biomass growth of Aspergillus niger using digital image processing

Júlio C.V. Dutra1, Selma da C. Terzi2, Juliana Vaz Bevilaqua3, Mônica C.T. Damaso4, Sônia Couri2, Marta A.P. Langone5, and Lilian F. Senna1. (1) Química Analítica, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier 524, PHLC, IQ, sl 427, Maracanã, Rio de Janeiro, Brazil, (2) Embrapa Agroindústria de Alimentos, Avenida das Américas 29501, Rio de Janeiro, Brazil, (3) Cenpes, PETROBRAS, Av. Jequitiba 950 radial 5 sala 552, Rio de Janeiro, Brazil, (4) Tecnologia de Alimentos, Universidade Federal Rural do Rio de Janeiro, BR 465, Km 7, Seropédica, Brazil, (5) Química Analítica, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier 524, PHLC, IQ, sl 427, Maracanã, Rio de Janeiro, Brazil

Fungal species have been easily cultured in solid state fermentation (SSF). This culture mode offers many advantages over commonly submerged fermentation processes. However the biomass growth monitoring of filamentous fungi in SSF is laborious.  Design and operation of a fermentation process could be improved by using methodologies for biomass estimation, which permit investigate the relationship among growth kinetic, biomass morphology and the fermentation product. The aim of this study was to monitor of biomass growth in Aspergillus niger SSF for lipase production using digital image processing technique. The strain A. niger (11T53A14) was cultivated for lipase production in SSF using wheat bran as support, which was enriched with liquid culture medium containing 0.91% (m/v) of ammonium sulphate. As the production of lipase can be inducer-dependent, the addition of different oils (castor, soybean, olive, corn, and palm oils) was tested. The lipase activity was determined by titration method and the maximum activity was obtained using 2% castor oil. In these conditions the growth was evaluated at each 24 hour for five days and the total area occupied by the hyphae was used for analysis. The images were acquired with a stereomicroscope coupled to a digital camera, and the results were processed using the software KS400â.  Glicosamine content and lipase activity were also determined. The results indicate that the digital process technique can be used for indirect biomass estimation in a solid-state fermentation process and that it will be possible to obtain a correlation between biomass and enzyme activity.

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