Biosourcing and optimization of fungal lipase production from cheap agro waste via solid state fermentation

The quest for economically viable sources of microbial lipases has been a primary focus for microbial enzymologists. This research aimed to screen, identify, and produce lipase from fungi using inexpensive agro-wastes as substrates. Samples of palm oil mill effluent were screened for lipolytic fungi using solid agar and submerged fermentation. Morphological and molecular methods were employed for isolate identification. Lipase activity was measured via spectrophotometric assays with p-nitrophenyl palmitate (p-NPP) as the substrate. The effect of medium composition on lipase production, the mineral and proximate compositions of the agro waste used as carbon sources via solid state fermentation were evaluated, followed by lipase purification and kinetic studies. Out of the 25 fungi screened, isolate GP11 identified as Aspergillus oryzae (Accession number: MN416218) exhibited the highest lipase activity and was selected for further studies. Medium composition significantly affected (p ≤ 0.05) lipase and biomass production across six fermentation media yielding 148.75 ± 2.94^e to 274.05 ± 13.70^a (U/mL) and 28.5 ± 1.41^c to 35.4 ± 1.77^a (g/L) respectively. Production media having glucose and peptone as carbon and organic nitrogen sources supported the highest lipase production. Agro waste composition influenced lipase production which ranged from 103.97 ± 2.88^g to 259.78 ± 8.45^a (U/mL). Wheat bran (WTB) (230.78 ± 7.79 U/mL) and rice bran (RCB) (211.62 ± 3.20 U/mL) with the highest carbohydrate contents supported the highest lipase production compared to orange peel, unripe plantain peel, ripe banana peel, ripe plantain peel, and sugar cane bagasse respectively. The purified lipase had 12.74- and 50.81%-fold purification and yield via Sephadex G-100 chromatography with a molecular weight of 53 kDa.