Removal of Phenanthrene by some microalga species and study of antioxidative compounds in Nostoc calcicola ISC 89

Purpose The accumulation of polycyclic aromatic hydrocarbons (PAHs) can cause adverse effects on the environment and human health. Microalgae species have the ability to remove and degrade PAHs. The present research provides novel insights to discover microalgae responses against phenanthrene (as a PAH) through an antioxidant defense response underlying reactive oxygen species detoxification and scavenging. Materials and methods This research was carried out to investigate the phenanthrene (PHE) removal by five microalgal species, namely, Scenedesmus sp. ISC 94, Chlorella sp. ISC 23, Nostoc calcicola ISC 89, Anabaena sp. ISC 88, and Leptolyngbya fragilis ISC 108. Screening of microalgal species for the PHE removal was done based on GC analysis and growth parameters under control conditions (without PHE) and at 0.1% PHE. Results and discussion The results showed that the tolerance of N. calcicola ISC 89 to PHE was more significant than other species under the studied condition. Antioxidant enzyme activity, total lipid, proline, and phenolic acid content increased significantly in PHE-treated N. calcicola ISC 89. It was also observed that there was a decrease in malondialdehyde (MDA) and H 2 O 2 contents with an increase of specific growth rate and dry weight in the tolerant species. Conclusions This research can provide new insights into the mechanism of N. calcicola ISC 89 tolerance against PHE-induced oxidative damage. Overall, this study suggests that N. calcicola ISC 89 can be used to remediate PAH-contaminated regions.