| Popis: |
Aim: Consequent from increased demands for lipase enzymes for various purposes, the soil environment of Jos North LGA of Plateau State, Nigeria was surveyed for lipase-producing fungi. Materials and Methods: Soil samples (300 g each) were collected randomly in triplicates from five locations (Terminus, Agwan Rukuba, Gada Biu, Farin Gada and Katako) in Jos North metropolis. Physicochemical properties (soil type, pH, temperature) and fungal counts of the soils were determined. Fungal isolates from the soil samples were preliminarily screened on phenol red agar for lipase production. Lipase activities of isolates with higher lipolytic potentials were determined using the spectrophotometric method with p-nitrophenyl dodecanoate serving as lipid substrate. Results: The soil samples were mostly of sandy and loamy types. Mean pH and temperature ranges of the soils were 6.7-7.5 and 23.5ºC - 26.8ºC respectively. Total fungal counts of the soil samples ranged between 2.0 x 103 cfu/g and 3.9 x 104 cfu/g with Angwan Rukuba having the highest count. Fungal isolates from the study included Aspergillus niger (100%), Aspergillus ochraceus (60%), Fusarium sp. (20%), Penicillium sp. (40%), Rhizopus stolonifer (60%) and Rhizopus sp (60%). R. stolonifer produced the highest lipolysis zone diameter (3.69 mm) on phenol red agar. A lipase activity of 0.183µmol/min/ml was recorded for R. stolonifer while A. niger, Fusarium sp. and Rhizopus sp. had equal lipase activities of 0.184µmol/min/ml. Conclusion: The findings show that the soil environment of Jos North LGA contain lipase-producing fungi which could be harnessed for industrial and environmental purposes after optimising the lipase production process. |
