Immobilization of Lipase-Producing Bacteria Acinetobacter baumannii on Paddy Straw Powder

The use of immobilized bacteria as biocatalyst is more interesting than pure enzyme because of its stability and low production cost. In this study, Acinetobacter baumannii isolated from oil contaminated soil in Pasar Anyar Singaraja Bali was immobilized on paddy straw powder to know the characteristics and stability of the lipase produced. The bacteria were grown in lipase production media with the composition of (w/v): 0.5% peptone, 0.5% yeast extract, 0.1% NaCl, 0.05% CaCl 2 , and then immobilized on the adsorbent which was activated by CaCl 2 solution with various concentrations (0 to 45% w/v). Immobilization was done by using adsorption technique by varying the culture age (8-24 hours). The activity of the lipase produced by the immobilized bacteria was tested and characterized by parameters of pH, temperature, catalysis stability and stability in ethanol and methanol. The results showed optimum immobilization was reached when using straw powder activated with 20% of CaCl 2 solution and at 20 hours of culture age. Immobilized bacteria showed optimum lipase activity at pH 8.5 and temperature of 45 °C with a value of 0.336 units/g. Immobilized bacteria were able to maintain their activity up to 51% after seven times of catalytic process. Interestingly, immobilized bacteria showed good stability in methanol, so it is best used as a biocatalyst in the production of biodiesel