Toxic Pyrene No Match for Chlorella Sorokiniana

RUDN University chemists, together with colleagues from India, Russia, and South Africa, have demonstrated that the green microalgae Chlorella sorokiniana can be used to clean toxic pyrene from wastewater, according to an announcement in the India Education Diary.

Pyrene is a cyclic organic compound formed in combustion processes such as in the internal combustion engine of a car. Algae absorb pyrene and at the same time change their metabolism to adapt to stressful conditions. As a result, more lipids are formed, from which safe biofuels can be efficiently synthesized, say the researchers.

Pyrene is one of the most common anthropogenic pollutants. One of the methods of cleaning the environment from pyrene is via bioremediation, i.e., cleaning with the help of plants, fungi and animals. RUDN University chemists along with their international colleagues have shown that water purification from pyrene with microalgae not only helps to get rid of harmful pollutants, but also to get eco-friendly biofuels.

The chemists studied the metabolism of Chlorella sorokiniana algae under the effect of pyrene. For 16 days, the algae were grown in a pyrene-contaminated environment and in a clean environment. The lipids that the algae produced during that time were then converted into biofuels.

Too high of a pyrene concentration (0.05%) almost destroyed the microalgae. At a concentration of 0.023%, 50% of the algae cells survived, and they showed high resistance to the pollutant.

During the experiment, algae from contaminated water gained almost as much weight as algae from water without pyrene — 444 mg per liter versus 449 mg. The composition of algae from the pyrene medium had less protein, but 21.2% more carbohydrates and 24.5% more lipids. The composition of these lipids was suitable for the synthesis of biofuels — the conversion efficiency was about 81%.

“This investigation reveals the promising potential of the oleaginous microalgae C. sorokiniana for the bioremediation of pyrene in conjunction with the induction of cellular lipids for biofuels,” said Dr. Kumar. Furthermore, the exploitation of lipids is not a limited product either, but rather reopens the enticements of biofuels from de-oiled biomass by hydrothermal liquefaction, pyrolysis, etc.

“In addition to these, various value-added products (such as carbohydrates, proteins, pigments, vitamins, etc.) as well as fertilizers are also potentially possible applications. Therefore, this research work demonstrates a diverse potential for further research and application opportunities.”