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

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 <i>Chlamydomonas reinhardtii</i> strains by nuclear and plastid transformation using genes <i>ars</i>C, <i>ɣ</i>-<i>ecs</i>, and <i>acr</i>3 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.