Characterization And Optimization Of Lipase Production From Soil Microorganisms:- Ejike, Emmanuel N

ABSTRACT

Lipases are industrially important enzymes that are produced by a variety of microorganisms. Lipase reduction by lipolytic bacteria, isolated from soil in Ohuhu Community in Umuahia North Local iovemment Area of Abia State, was detected in a medium containing olive oil (3%) and rhodamine j. dye (1%)- Among the several bacteria screened, a strain was selected for lipase production as it ihowed the largest orange fluorescence under UV light, indicating effective production of lipase. Lipase production was carried out using a basal medium containing KH2PO4, Na2SC>4, MgSO4.7H2O, /east extract, K2HPO4, Peptone, Glucose and Olive oil. It was investigated in a shake flask culture at 37°C for 48hours. Morphological, biochemical and molecular characterization ofthe isolate identified it as Serratia marcescens. The study of different carbon sources on lipase production revealed that glucose yielded higher lipase production of 7.6Umf1 than sucrose (b^Umf1), fructose (4.9Umf1), starch (3.6Umr’), lactose (2.4Umr’) and maltose (l.dUmf1). Subsequently, 2.5% concentration of glucose yielded higher lipase activity than the other concentrations (0.5%-4%) of glucose tested. Screening for the best nitrogen source revealed that peptone gave the highest activity of 28.5Uml'1, others are tryptone (25.5Umr’), yeast extract (20.0Umr') and meat extract (22.4Umf'), while NH4CI showed the least activity of 7.0Uml'1. Also, 2.5% concentration of peptone gave the highest activity compared with other concentrations (0.5-4.5%) tested. Among the natural oils, olive oil gave the highest lipase activity of 25.2Umf' compared with other oils and 0.8% concentration of olive oil was found to increase lipase production by 36.2Umr'. Other lipid sources observed were palm oil (20.5Umf1), groundnut oil (19.5Umr’), soy oil (lb.dUmf1) and crude oil (14.8Umr‘). The most suitable source of metal ion was MgSO4 (29.5Umf’) followed by MnSO4 (27.9Umfl), KC1 had the least activity of 13.9Umr’. Organic solvents on lipase activity revealed that methanol yielded higher lipase activity of42.7Uml'1 than ethanol (30.5Umr’), isopropanol (IS.bUmf1) and acetone (5.2Umr*). Methanol showed significant high lipase activity at 1.5% concentrations. Various physicochemical parameters that were investigated such as pH, temperature and rate of agitation revealed that pH 6 and Temperature of40°C at 150 rpm gave optimal lipase activity. The results promises high production of lipase with an inexpensive and simple medium containing palm oil, peptone, and magnesium sulfate, at pH 6.0 and 150 rpm for 48hrs (2days). This could be employed in the enzyme industry for commercial purpose