Size Exclusion Chromatography Protein Profile of Selenastrum capricornutum Culture Extracts Degrading Benzo(a)Pyrene

Abstract

Benzo[a]pyrene (B[a]P) is an environmentally ubiquitous, persistent, and carcinogenic pollutant belonging to the polycyclic aromatic hydrocarbons (PAHs) family. Several methods have been employed to follow PAH degradation by bacteria. However, there is very scarce information about microalgae as bioremediation species. In this work, we investigated the protein profile for B[a]P degradation by the Selenastrum capricornutum algae culture extract employing high-performance liquid chromatography (HPLC) in size exclusion chromatography mode (SEC) and electrophoresis (sodium dodecyl sulfate-polyacrylamide gel electrophoresis [SDS-PAGE]). We evaluated the degradation of crude extracts (CEs) and SEC fractions, and we found the presence of trace levels of 4, 5-dihydrodiolbenzo[a]pyrene (4,5-dB[a]P) and 7,8-dihydrodiolbenzo[a]pyrene (7,8-dB[a]P) in cis geometry as B[a]P degradation products. SEC chromatographic profile comparison of CEs and SEC fractions, both exposed to B[a]P along with the corresponding controls, allowed us the identification of molecular weights (MWs) of a multi-component system involved in the B[a]P biodegradation through protein over-production. Electrophoresis analysis showed several protein components, with MWs between 10 and 250 kDa, where two subunits of 38.15–41.97 and 82.73 ± 3.15 kDa suggested the presence of multi-component di-oxygenases in the early stages of B[a]P biodegradation by S. capricornutum cultures. This work extends the knowledge of the biodegradation process of high molecular PAHs by microalgae.

Keywords:

• B[a]P
• microalgae
• biodegradation
• SEC
• electrophoresis
• protein

Acknowledgments

Consejo Nacional de Ciencia y Tecnología de México (CONACYT) project CB No. 283377 is thanked for the budget support and the doctoral scholarship awarded to J. E. Becerril Mercado No. 577195. Dirección General de Asuntos de Personal Académico from Universidad Nacional Autónoma de México (DGAPA-UNAM) is also thanked for the PAPIIT IT202718 project and to the PAIP project 50009034 of the Faculty of Chemistry, UNAM. Finally, the authors thank R. Covarrubias Herrera for the technical assistance for liquid chromatography.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México; Universidad Nacional Autonoma de México, Facultad de Química.