Comparative Physiological and Biochemical Responses of Chlorella sorokiniana (PX796505) and Tetradesmus wisconsinensis (PX454383) under Arsenic Stress: Mechanistic Insights into a Sustainable Dual-Application Approach

Arsenic contamination of aquatic ecosystems constitutes one of the major environmental and public health concerns. Therefore, remediation strategies should be sustainable and low cost. The present study comprises a comparative physiological and biochemical evaluation of Chlorella sorokiniana (PX796505) and Tetradesmus wisconsinensis (PX454383) under arsenite [As(III)] and arsenate [As(V)] stress, with special emphasis on arsenic removal efficiency and bioenergy potential. Microalgal cultures were treated with arsenic concentrations ranging from 0 to 125 mg L⁻¹ for 28 days. Growth performance, chlorophyll content, biochemical composition (proteins, carbohydrates, and lipids), ultrastructural alterations, and arsenic removal efficiency were systematically evaluated. Both microalgae exhibited clear species- and speciation-dependent responses. Arsenite caused stronger early toxicity than arsenate. This resulted in pronounced growth inhibition and chlorophyll depletion, particularly in C. sorokiniana . Despite this initial sensitivity, C. sorokiniana expressed higher tolerance under environmentally relevant arsenate concentrations and reached higher arsenic removal efficiency, revealing its suitability for long-term bioremediation purposes. On the other hand, T. wisconsinensis had exhibited significant lipid amassment upon exposure to both arsenic species, which reflected a stress-induced carbon reallocation toward lipid biosynthesis, improving its biofuel aptitude. Ultrastructural analysis revealed active arsenic-induced cellular remodeling in both species, endorsing the activation of adaptive and detoxification mechanisms. In general, this study demonstrated that both studied microalgae could serve a dual functional role: C. sorokiniana as an efficient arsenic scavenger and T. wisconsinensis for value-added biomass toward bioenergy. This work provides an important mechanistic and application-oriented framework that merges arsenic bioremediation with renewable bioresource production.