Poster (Painel)
Autores:Priscila Ferreira Pires Eustachio (UFVJM - Universidade Federal dos Vales do Jequitinhonha e Mucuri) ; Alexandre Soares dos Santos (UFVJM - Universidade Federal dos Vales do Jequitinhonha e Mucuri) ; Lilian Araújo Pantoja (UFVJM - Universidade Federal dos Vales do Jequitinhonha e Mucuri) ; Ana Paula de Figueiredo Conte Vanzela (UFVJM - Universidade Federal dos Vales do Jequitinhonha e Mucuri)


Lipases belong to a special class of ester hydrolysing enzymes presenting a variety of applications, including food preparation, incorporation in detergents and esterification of fat acids with simple alcohols like ethanol or methanol (biodiesel production). In this work, a central composite experimental design was prepared with the software Statistica 7.0 to determine the critical values of soy oil and ammonium sulphate for lipase production by Penicillium sp. T9.1. Soy oil concentration varied from 0.8 (-1) to 3.2% (+1) and ammonium sulphate varied from 0.8 (-1) to 4.2 g/l (+1), according to information previously obtained through factorial planning. It were conducted 4 fermentations combining high and low levels of both variables, 4 axial points (α = 1.41) and 5 central value fermentations. Temperature and agitation were kept at 30 ºC and 150 rpm. Lipase activity (triplicate) were determined in the filtrates by titration after triglyceride hydrolysis. Most of the fermentations yielded maximum lipase production after 72 h, whereas the highest activities were obtained in the central points (0.9 U . ml-1 . min-1) and in fermentations 4 (1.2 U . ml-1 . Min-1) and 6 (1 U . ml-1. Min-1). Fermentation 4 contained the high levels of soy oil and ammonium sulphate, while fermentation 6 combined an axial point of soy oil (3.7%) and the central value of ammonium sulphate (2.5 g/l). In fermentation 7, it was determined 1.3 U . ml-1. Min-1of lipase activity, but the time of fermentation was increased to 96 h. Data analysis with the software Statistica 7.0 showed that both variables presented quadratic effects that were significant for the lipase activity (R2= 0.96). Surface response graphics showed that a maximum lipase activity would be produced in media supplemented with approximately 2.5-4% soy oil and 2-3.5% ammonium sulphate. The software gave a maximum solution of 1.14 U . ml-1. Min-1for the critical values 3.5% soy oil and 3.5 g/l ammonium sulphate. Thus, the strain T9.1 may be used to produced above 1 U . ml-1. Min-1of true lipase activity, which is promising since the time of production was short in comparison to fermentation with other strains, whereas many of these produce esterases, not true lipases. Other variables (pH, temperature, agitation) will be further analyzed to increase the magnitude of lipase production.

Palavras-chave:  central composite design, fermentation, lipase, optimization, Penicillium sp.