초록
<P><B>Abstract</B></P> <P>This study sets out to compare three techniques for extracting polygalacturonase (PG) from <I>Aspergillus aculeatus</I> URM4953, namely, precipitation by organic solvent (ethanol and acetone), precipitation by ammonium sulfate salt and extraction by aqueous two-phase systems (ATPS) PEG/Citrate using a factorial design 2<SUP>4</SUP>. Afterwards, a central composite design (CCD) was used to optimize PG extraction by ATPS. The variables studied were concentrations of PEG (C<SUB>PEG</SUB>) and citrate (C<SUB>CIT</SUB>), PEG molar mass (M<SUB>PEG</SUB>) and pH. The responses analyzed were the partition coefficient (K), the activity yield (Y) and the purification factor (PF). The thermodynamic parameters of the optimized ATPS partition were estimated as a function of temperature. Among the techniques used, only the ATPS was able to pre-purify the PG (PF = 1.8) with an 85% yield. Optimization increased the PF value to 2.3. The best condition was 23% C<SUB>CIT</SUB>, 19% C<SUB>PEG</SUB> with the M<SUB>PEG</SUB> and pH set to 8000 g/mol and 8, respectively. The mathematical models of the CCD showed a high adjustment to predict the extraction of polygalacturonase from <I>Aspergillus aculeatus</I> URM4953 by ATPS. The thermodynamic parameters ΔG°<SUB>m</SUB> (−3.15 kJ/mol), ΔH°<SUB>m</SUB> (9.14 kJ/mol) and ΔS°<SUB>m</SUB> (41.2 J/Kmol) of partition showed that the preferential migration of almost all proteins from the crude extract to the salt rich-phase by increasing the temperature was spontaneous, while the PG preferred the PEG-rich phase. The ATPS showed the best performance as a first step for pre-purifying the PG from <I>Aspergillus aculeatus</I> URM4953.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The precipitation techniques showed the highest PG yield but did not pre-purified it. </LI> <LI> Among the techniques used only ATPS pre-purified the PG from <I>A. aculeatus</I> URM4953. </LI> <LI> The ATPS optimized extraction pre-purified the PG in 2.3 with a yield of 77.6%. </LI> <LI> The thermodynamic parameters showed the preference of the PG to PEG rich Phase. </LI> </UL> </P>