Cellulase production by Aspergillus fumigatus A4112 and the potential use of the enzyme in cooperation with surfactant to enhance floating oil recovery and methane production from palm oil mill effluent

Abstract

This research performed cellulase production by Aspergillus fumigatus A4112 and evaluated its potential use in palm oil mill effluent (POME) hydrolysis to recover oil simultaneously with the generation of fermentable sugar useful for biofuel production under non-sterilized conditions. Empty fruit bunch (EFB) without pretreatment was used as carbon source. The combination of nitrogen sources facilitated CMCase production. The maximum activity (3.27 U/mL) was obtained by 1.0 g/L peptone and 1.5 g/L (NH4)2SO4 and 20 g/L EFB at 40 °C for 7 days. High level of FPase activity (39.51 U/mL) was also obtained. Interestingly, the enzyme retained its cellulase activities more than 60% at ambient temperature over 15 days. In enzymatic hydrolysis, Triton X-100 was an effective surfactant to increase total oil recovery in the floating form. High yield of reducing sugar (50.13 g/L) and 21% (v/v) of floating oil was recoverable at 65 °C for 48 h. Methane content of the raw POME increased from 41.49 to 64.94% by using de-oiled POME hydrolysate which was higher than using the POME hydrolysate (59.82%). The results demonstrate the feasibility of the constructed process for oil recovery coupled with a subsequent step for methane yield enhancement in biogas production process that benefits the palm oil industry.