Characterization of a Polyphenol Oxidase and Lipase Produced by Microbes Derived from Palm Oil Sludge

Abstract

Introduction: The waste-to-wealth concept was applied in this study. Our main objective was to identify and evaluate several microorganisms responsible for the production of important industrial enzymes using sludge from palm oil processing. We were able to isolate several bacteria that are tyrosinase producers: Bacillus cereus, Acinobacter seifertii, Klebsiella variicola and Pseudomonas stutzeri. Laccase producers Trametes polyzona, Bacillus subtilis, Bacillus pumilus and Staphylococcus condimenti, as well as lipase producers. Methods: In addition, we focused specifically on B. cereus because we knew that it produces tyrosinase. Lipase is another target enzyme, and S. condimenti was found to be a hyperproducer. Production conditions included a 24-hour incubation period at 40°C and a pH of 6.0, while typical substrates such as starch and coconut oil were used. Results: Preliminary protein purification studies identified a 43 kDa lipase that is active at pH 7.0 and 40°C. Salts such as NaCl, various detergents such as Triton X-100 and Tween-80 as well as many metal ions enhanced the activity and made the enzyme unique in its biological function. Conclusion: Even with EDTA (2.5 mM), which does not completely block its function, only 40% inhibition was observed. Only a few organic solvents such as butanol, acetone and DMF are involved in inhibiting its activity.