Study of the impact of mild detergents on the recovery and the activity of Chlorella variabilis’s Fatty acid photodecarboxylase

Details

Supervisors

Debecker, Damien P. ; Soumillion, Patrice

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en chimie et bioindustries

Abstract

In a world where everything is changing fast, the chemical industry in general has to evolve with new environmental restrictions. The society asks also for new sustainable ways in industrial productions. Therefore, biology is a great technical and inspirational support for a vast range of application. Currently, petroleum has an important role in various domains of our daily life. With its rarefication and the price increase of the barrel, alternatives are sought in bio-based processes and biomass valorization among others. In the domain of biofuels, interest in microalgae has increased in the last decade for their potential. Chlorella variabilis is one example that is studied in the fuel industry for the production of bioethanol. More recently, it appears that their oil composition would be more interesting for the production of FAMEs (Fatty acids methyl esters). As photoautotrophs, microalgae manage to build their oil composition up to 70% of their total weight. During the analysis of a heterogenous group of microalgae, researchers observed alkane and alkene production. After further investigation they came across an enzyme they baptized Chlorella variabilis’s Fatty acid Photodecarboxylase, or CvFAP. As indicated by its name, it is an enzyme that via illumination can decarboxylate fatty acids to produce alkanes or alkenes and carbon dioxide. This protein was first discovered in Chlorella variabilis but homologous proteins were found in other microalgae strains. One of the observations is that the purified enzyme is less active than when it is in the cell lysate. Adding FAD (Flavin adenine dinucleotide), its cofactor, helps the enzymatic activity. Yet the results are still not as good as in the lysate. The other researches use DMSO as cosolvent for the solubilization of the fatty acids in the medium. The DMSO can be replaced by mild detergents who will keep the role of solubilizing the substrates but are more environmentally friendly. In this paper, the focus is on the use of these surfactants. Firstly, the addition of detergents in the production and purification steps help recovering the photoenzyme from the cell debris in the pellet. Secondly, some clues are presented that those surfactants could be the enzymatic activity enhancer in the photocatalytic assays.