Bioremediation of Per- and Poly-Fluoroalkyl Substances (PFAS) by Synechocystis sp. PCC 6803: A Chassis for a Synthetic Biology Approach

Abstract

One of the main concerns in industrialized countries is represented by per- and poly-fluoroalkyl substances (PFAS), persistent contaminants hardly to be dealt with by conventional wastewater treatment processes. Phyco-remediation was proposed as a green alternative method to treat wastewater. Synechocystis sp. PCC6803 is a unicellular photosynthetic organism candidate for bioremediation approaches based on synthetic biology, as it is able to survive in a wide range of polluted waters. In this work, we assessed the possibility of applying Synechocystis in PFAS-enriched waters, which was never reported in the previous literature. Respirometry was applied to evaluate short-term toxicity of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), which did not affect growth up to 0.5 and 4 mg L−1, respectively. Continuous and batch systems were used to assess the long-term effects, and no toxicity was highlighted for both compounds at quite high concentration (1 mg L−1). A partial removal was observed for PFOS and PFOA, (88% and 37%, with removal rates of about 0.15 and 0.36 mg L−1 d−1, respectively). Measurements in fractionated biomass suggested a role for Synechocystis in the sequestration of PFAS: PFOS is mainly internalized in the cell, while PFOA is somehow transformed by still unknown pathways. A preliminary bioinformatic search gave hints on transporters and enzymes possibly involved in such sequestration/transformation processes, opening the route to metabolic engineering in the perspective application of this cyanobacterium as a new phyco-remediation tool, based on synthetic biology.

Biodegradation Potential of C7-C10 Perfluorocarboxylic Acids and Data from the Genome of a New Strain of Pseudomonas mosselii 5(3)

“…Most of this category is associated with the degradation of various aromatic compounds (including ethylbenzene, nitrotoluene xylene, styrene, naphthalene, polycyclic aromatic hydrocarbon, aminobenzoate, dioxin and atrazine). According to [ 57 ], laccases and dehalogenases emerge as the most promising contenders for PFCA biotransformation enzymes. These enzymes are currently under the scrutiny of scientists investigating biocatalysis as a tool for removing persistent pollutants, including PFCA.…”

Environmental Contaminants of Emerging Concern: Occurrence and Remediation

“…The uptake of the PFAS family compounds was observed and mechanism behind the sequestration was not proposed yet. They found PFAS in the membrane fractions and the bioinformatic analysis found laccases and dehalogenases in the proteome of the blue green alga [52]. A bioinspired #D nanostructure consisting of cellulose and lignin fibres nanofibers was fabricated initially and then the fungus Irpex lacteus was cultured on the nanocomposite could effectively adsorb and remove PFAS.…”

Removal of PFAS by Biological Methods

“…In case of using synthetic biology as a bioremediation approach, Marco et al (2021) [31] proposed Phycoremediation as a green alternative approach to wastewater treatment. In this study, the possibility of using Synechocystis sp.…”