The expression of arsC, ɣ-ecs, and acr3 in Chlamydomonas reinhardtii resulted in an enhanced arsenic removal efficiency compared to a wild-type strain.

Abstract

Arsenic in groundwater is a severe problem in México, where its concentration in drinking water exceeds the limit established by the World Health Organization's reference value, and represents a public health problem in the San Luis Potosí, where the affected populations live in semiarid areas without access to arsenic reduction technologies. We developed transgenic Chlamydomonas reinhardtii strains by nuclear and plastid transformation using genes arsC, ɣ-ecs, and acr3 as a cost-effective and noninvasive phytoremediation strategy. The capacity to remove arsenic was evaluated under diverse As(V) concentrations (0.5-2 mg/L) and two phosphate levels (375 and 37.5 µM). The plastid and the double-recombinant strains exhibited substantial As(V) removal capabilities, with a 20% and 80% increase versus wild-type (WT) strain, at the lowest phosphate concentration, the double-recombinant strain exhibited an arsenic uptake rate up to 12 times higher than that of the wild-type (WT) strain, indicating that the genetic modifications enhanced arsenic removal. The double-recombinant microalgae demonstrated exceptional tolerance to As(V), maintaining a µ_max value comparable to that of other strains, indicating sustained cell growth under arsenic stress. This strategy offers a viable platform for arsenic phytoremediation and holds promise for future implementation in public-scale systems.