Light intensity affects tolerance of pyrene in Chlorella vulgaris and Scenedesmus acutus

Abbreviations : C – control; Chl – chlorophyll; F 0 – minimal fluorescence; F m – maximum fluorescence; F v /F 0 – efficiency of the water- splitting complex; F v /F m – maximal quantum yield of PSII photochemistry; HL – high light; LL – low light; PAHs – polycyclic aromatic hydrocarbons; PYR – pyrene; SP – saturation pulse; Y (II) – quantum yield of PSII; Y (NO) – yield of nonregulated energy dissipation; Y (NPQ) – yield of regulated energy dissipation. Acknowledgments : RST thanks the Council of Scientific and Industrial Research for the CSIR-RA fellowship [09/301/ (0134)/2018-EMR-I]. PR thanks University Grants Commission (UGC), India for awarding UGC–NET Junior Research Fellowship [F.16(DEC.2016)/2017(NET)]. Conflict of interest : The authors declare that they have no conflict of interest. and Scenedesmus acutus . Both species were cultured under low light, LL [50–60 µmol(photon) m –2 s –1 ], and high light, HL [100–110 µmol(photon) m –2 s –1 ] conditions to study the effects of pyrene (PYR) toxicity on growth parameters, the content of biomolecules, chlorophyll content, and photosynthetic efficiency. In the presence of PYR, S. acutus could grow well in LL and HL intensity. On the other hand, C. vulgaris showed a drastic decrease in growth and photosynthesis during HL conditions due to PYR toxicity. Regulation of nonphotochemical and photochemical quenching was responsible for the survival of S. acutus under PYR toxicity in LL and HL conditions. Thus, S. acutus seems to be a more promising candidate for pyrene degradation under varying light conditions.