Temperature and pH-Driven Lipase Dynamics of Penicillium spp. and Aspergillus niger for Sustainable Treatment of Agro-industrial Wastewater

Abstract

The increasing environmental burden of palm oil mill effluent (POME) has necessitated the search for eco-friendly remediation strategies. This study investigated the potential of Penicillium spp. and Aspergillus niger isolated from palm oil mill press fibre (PPF) for lipase production and their application in the biodegradation of POME. The fungi were screened for lipase activity using Tween 80 agar, Tributyrin agar, and Phenol Red agar. Conventional identification methods were employed. PPF from a local oil mill was processed for solid-state fermentation (SSF). Lipase production involved moistening 3 g of PPF with 10 mL of basal medium, sterilizing at 121°C and 15 psi for 20 minutes, and inoculating with 2 mL of spore suspension (1.0 × 10⁷ spores/mL). Lipase activity was measured spectrophotometrically using p-nitrophenyl laurate (p-NPL) over 15 days at varying temperatures (25°C – 45°C ) and pH levels (3.0 – 7.5). Initial lipase yields were 104 U/mL for Penicillium spp. and 398 U/mL for A. niger. Optimisation significantly enhanced enzyme production. Penicillium spp. peaked at 35°C (373 U/mL) and pH 6.5 – 7.0 (771 U/mL), while A. niger peaked at 25°C (387 U/mL) and pH 7.0 – 7.5 (755 U/mL). Statistically significant differences (P =.05) were observed. Crude lipases showed effective POME degradation, with Penicillium spp. achieving 99.77% at pH 7.0, and A. niger 88.77% at pH 6.5. These findings demonstrate that fungal-derived lipases are promising tools for sustainable bioremediation of lipid-rich effluents, and that PPF is a viable substrate for enzyme production.