Researchers from the Chinese University of Hong Kong (CUHK) found a novel and cost-efficient way of generating enzymes in high yield used in the production of biodiesel.
Researchers from the School of Life Sciences at the Chinese University of Hong Kong (CUHK) recently published a noteworthy paper in the Journal of the American Chemical Society, reporting a new technique that improves the efficiency and lowers the cost of producing biodiesel. This method focusses on obtaining key enzymes for biodiesel production from bacteria and provides a higher-yield alternative to the conventional method of biodiesel production.
Enzymes are biocatalysts – small biomolecules that speed up the rate of essential biochemical processes in many organisms. Leveraging on this characteristic, custom-built enzymes are employed widely by chemists to expedite chemical processes like the manufacture of medicines and in industrial processes like the production of biodiesel.
Biodiesel is a relatively new eco-friendly and renewable fuel. It is often mixed with petroleum diesel for its use as fuel and emits lower levels of harmful environmental pollutants as compared to pure diesel, which is still currently widely used.
Animal fats, vegetable oils or methanol are usually the base ingredients for biodiesel production. These substances are traditionally converted to biodiesel with the help of a base catalyst. However, the utilization of base catalysts is neither energy efficient nor environmentally-friendly, as it requires high temperatures for base catalyst activation and generates waste materials that contribute to water pollution in the process. Enzymes, on the other hand, present a more eco-conscious option that also consumes less energy. Enzymes are able to achieve the same effect as base catalysts but at a lower temperature and can convert lipids in animal fats or vegetable oils directly into biodiesel, hence overcoming some of the challenges of using base catalysts in biodiesel production.
However, currently, the use of enzymes is not optimized in terms of cost-effectiveness and efficiency as time-consuming purification and subsequent immobilization procedures are needed to allow the recycling and reutilisation of enzymes for the next round of production. Hence, the high production cost of using enzymes is a main deterrent for biodiesel production firms to switch from base catalysts to enzymes as an eco-friendly alternative.
The CUHK team comprising of Dr Bradley Heater, Dr Zaofeng Yang and Dr Marianne Lee from the School of Life Sciences, led by Professor Michael Chan championed this innovative way of retaining enzymes in the pores of the naturally-occurring Cry3Aa protein crystals in the strain of bacteria – Bacillus thuringiensis. Subsequently these enzymes were isolated in a one-step procedure, which simplifies the isolation process considerably.
The ingenuity of this new technique lies in the fact that when the Cry3Aa crystals are formed in the same bacterial cell, multiple copies of enzymes will be produced and maintained within the pores of the crystals, from which they can be extracted for biodiesel production. The retention of such enzymes within the pores of the crystals increases their stability, hence prolonging the period of use of these enzymes.
Dr Bradley Heater, the lead author of the paper commented, “the real elegance of this technology is that the bacteria cells do all the hard work of producing the catalyst – all we have to do is separate the crystals from the cell debris. Currently, we can use this method to produce an enzyme that converts waste cooking oil to biodiesel, but we should be able to trap other enzymes to perform different chemistry as well.”
Funded by the Research Grants Council and Innovation and Technology Fund, Prof Chan’s team will continue to investigate the feasibility and efficiency of using Cry3Aa crystals to produce recyclable catalysts for biodiesel production and its potential application in the production of other commodity chemicals. [APBN]