Purification and characterisation of Bacillus thuringiensis lipase isolated from palm kernel processing site for biodiesel production

The increase in global energy consumption led in the use of fossil fuels, which increased the carbon footprint in the environment. This has increased the need for biodiesel as a sustainable energy source. Recent advances in biodiesel production have highlighted lipase as a sustainable biocatalyst that eliminates the need for chemical catalysts. However, the rising cost of producing biodiesel as a result of substrate and lipase costs underscores the need for alternative local sourcing for microbial lipase and its feedstock.

This study isolated, partially purified, and characterized a lipase-producing bacterium, Bacillus thuringiensis, from a palm kernel processing site to evaluate the catalytic potential of its lipase for biodiesel synthesis.

The enzyme was employed to catalyze the transesterification of palm kernel oil into biodiesel. The resulting biodiesel was characterized using Fourier Transform Infrared (FTIR) spectroscopy, and Gas Chromatography Mass spectroscopy, its fuel properties were evaluated in accordance with American Society for Testing and Materials (ASTM) standards.

The partially purified Bacillus thuringiensis lipase (70.26 kDa) presents optimal activity at pH 7.5 and 55 °C, remaining stable for 45 min at 45 °C. It demonstrated enhanced catalytic activity in all polar solvents used in this work. Biodiesel produced in this study presents spectra with the functional group of biodiesel on both FTIR and GCMS with a conversion yield of 76.7 ± 9.8% The fuel and chemical properties of the produced biodiesel such as Pour point − 7 °C, cloud point − 3 °C, viscosity of 6.9 mm²/s. complied with international specification (ASTM).

The study demonstrated that the Bacillus thuringiensis strain isolated from the palm kernel processing site produced an alkaline, thermostable lipase with efficient catalytic activity for the transesterification of palm kernel oil into biodiesel.