Tailoring of an extracelular lipase activity from Aspergillus niger MYA 135 by submerged fermentation: medium optimization, performance and molecular characterization.

PERA, LICIA MARÍA; SALVATIERRA, NATALIA HEBE; REGNER, ERIKA LUCÍA; BAIGORI, MARIO DOMINGO

CABA

Congreso; Reunión conjunta de sociedades de biociencias; 2017

Reunión conjunta de sociedades de biociencias

Lipases (EC 3.1.1.3) are important industrial enzymes due to their versatile applications. In this work, the medium engineering strategy was used for tailoring an extracellular lipase activity from Aspergillus niger MYA ATCC 135. Previously, among eleven variables, the carbon/nitrogen ratio and the concentration of both olive oil and FeCl3 were identified as significant parameters. Thus, the level of those important input factors was optimized to maximize the lipase production using a central composite design. All experiments were performed in duplicate and analyzed with the Minitab software for Windows. The hydrolytic activity was measured with p-nitrophenyl palmitate (C16) as substrate. The molar extinction coefficient of p-nitrophenol (p-NP) under the given assay conditions was 0.00979 μM-1 cm-1. One unit of enzyme activity (U) was defined as the amount of biocatalyst that released 1 μmol of p-NP per min. The enzymatic activity was expressed as U per liter of supernatant. As a result, the optimal culture conditions were the following: 3 % olive oil (X1), 0.20 g/l FeCl3 (X2) and a carbon/nitrogen ratio (X3) of 0.37. The effect of each variable was also analyzed; the linear coefficient of X1 and X3, the interaction terms coefficients of X1and X2, and the quadratic coefficients of both X22 and X32 were significant, as their P values were below 0.05. In addition, the P-value for the lack-of-fit test (0.578) showed the adequacy of the model. This is also verified by the R2 (80.10 %) and the Adj R2 (73.24%) coefficients indicating the percentage of variability that is explained by the model. Besides, the thin layer chromatography was used to analyze the performance of these biocatalysts in the biodiesel synthesis. Finally, the gene encoding for the lipase activity was identified from cDNA obtained by retrotranscription using the saline medium with olive oil as inductor. This work was supported by FONCyT (PICT 2015- 2596), CONICET (PIP 339) and UNT (PIUNT E548/3).