Mycelium-bound lipase production from Aspergillus niger MYA 135, and its potential applications for the transesterification of ethanol

Abstract

The potential biotecnological applications of both constitutive and inducible lipase sources from Aspergillus niger MYA 135 were evaluated. To this end, the effect of environmental conditions on mycelium-bound lipase production from this strain was studied, when cultured either in the absence or presence of 2% olive oil. It was previously reported that mycelium-bound lipase from Aspergillus niger MYA 135 possess high stability in reaction mixtures containing ethanol; which could be especially important for their use in biodiesel synthesis. In this connection, the performance of the lipase sources produced in the transesterification of ethanol using p-nitrophenyl palmitate as acyl donor was also explored. Under our assay conditions, hydrolytic and synthetic activity of the mycelia produced in the absence or presence of olive oil were not highly correlated. While the hydrolytic activity was strongly increased by the addition of lipid to the culture medium, the best performance in the transesterification reactions of ethanol were associated with mycelia produced in absence of olive oil. Interestingly, the supplementation of the culture medium with Fe+3 increased the transesterification activity by 71%, as compared to the activity previously reported for this strain. Therefore, the constitutive lipase sources from Aspergillus niger MYA 135 are considered to be promising for industrial biodiesel-fuel production.