Enhanced lipolytic activity potential of mutant Bacillus niacini EMB-5 Grown on Palm Oil Mill Effluent (POME) and biochemical characterization of purified lipase
2019
Oyedele, Solomon A. | Ayodeji, Adeyemi O. | Bamidele, Olufemi S. | Ajele, Joshua O. | Fabunmi, Temitope B.
Palm oil mill effluent (POME) is a major waste from oil-palm industries often disposed indiscriminately into surrounding water bodies, adding up to retarding soil health and environmental pollution. Here, POME was beneficially used for lipase production by newly isolated microorganisms from oil-polluted soil. The identified microorganisms, using 16S rRNA gene analysis, were screened for lipolytic activity and treated with ethidium bromide for possible mutation in nucleotide sequence and enhancement of their lipolytic potential. A mutant strain of Bacillus niacini as confirmed by CodonCode aligner software showed the highest lipolytic activity compared to the wild type organisms. The crude lipase produced from the mutant strain was purified to apparent homogeneity using ammonium sulphate precipitation, ion-exchange chromatography on DEAE-Sephadex A-50 and gel-filtration on Sephadex G-100. Some biochemical properties of the lipase were studied prior to its application for the hydrolysis of different oils. The 59 kDa purified lipase exhibited optimal activity at pH 9.0 and 40 °C. The enzyme is alkaline thermostable being active at pH 8.0–12 and retained about 60% of initial activity after 60 min of incubation at 90 °C. At 10 mM salt concentration, Al3+ and Ca2+ modulated the activity of the enzyme but inhibited by Cu2+, Hg2+, EDTA, β-mercaptoethanol, SDS and Urea. The Km and Vmax of the lipase with olive oil as substrate are respectively, 6.12 mg/mL and 59.64 μmol/min/mg as the enzyme was able to hydrolyze various natural oils. These remarkable properties make the purified EMB-5 lipase employable for biotechnological applications in lipid-utilizing industries.
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