Harnessing SDS as a source of sulfur: a bioremediation strategy of Fischerella sp. lmga1.

Sodium dodecyl sulfate (SDS), a widely used anionic surfactant, is a pervasive aquatic pollutant with documented ecotoxicity and persistence in the environment. In this study, we investigated metabolic response of the filamentous, heterocytous cyanobacterium Fischerella sp. lmga1 under sulfur starvation, focusing on its capacity to degrade SDS and utilize it as an alternative sulfur source. Sulfur-deprived cultures supplemented with 150 µM SDS initially exhibited chlorosis and physiological stress, but showed significant recovery by 14 days, including increased growth and better photosynthetic performance. A significant rise in intracellular sulfur content was observed, suggesting active sulfur acquisition. Expression analysis revealed strong induction of genes involved in sulfur uptake and assimilation (e.g., cysT, cysW, sbp, sat), alongside an ~ 880-fold upregulation of sdsA1 on day 10, encoding an SDS hydrolase. Correlation analyses showed that increased sdsA1 expression coincided with improvements in viability and sulfur status. This underscored a coordinated mechanism of SDS degradation and concomitant sulfur assimilation in Fischerella, indicating towards a novel adaptive strategy. Thus, this study establishes Fischerella as a promising candidate for bioremediation of sulfonated pollutants in aquatic systems and expands the knowledge of metabolic plasticity of cyanobacteria.