A Novel Sulfatase for Acesulfame Degradation in Wastewater Treatment Plants as Evidenced from <i>Shinella</i> Strains

The artificial sweetener acesulfame is a persistent pollutant in wastewater worldwide. So far, only a few bacterial isolates were recently found to degrade acesulfame efficiently. In <i>Bosea</i> and <i>Chelatococcus</i> strains, a Mn²⁺-dependent metallo-β-lactamase-type sulfatase and an amidase signature family enzyme catalyze acesulfame hydrolysis via acetoacetamide-<i>N</i>-sulfonate to acetoacetate. Here, we describe a new acesulfame sulfatase in <i>Shinella</i> strains isolated from wastewater treatment plants in Germany. Their genomes do not encode the Mn²⁺-dependent sulfatase. Instead, a formylglycine-dependent sulfatase gene was found, together with the acetoacetamide-<i>N</i>-sulfonate amidase gene on a plasmid shared by all known acesulfame-degrading <i>Shinella</i> strains. Heterologous expression, proteomics, and size exclusion chromatography corroborated the physiological function of the <i>Shinella</i> sulfatase in acesulfame hydrolysis. Since both acesulfame sulfatase types are absent in other bacterial genomes or metagenome-assembled genomes, we surveyed 73 tera base pairs of wastewater-associated metagenome raw data sets. <i>Bosea</i>/<i>Chelatococcus</i> sulfatase gene signatures were regularly found from 2013, particularly in North America, Europe, and East Asia, whereas <i>Shinella</i> sulfatase gene signatures were first detected in 2020. Moreover, signatures for the <i>Shinella</i> sulfatase and amidase genes co-occur only in six data sets from China, Finland, and Mexico, suggesting that the <i>Shinella</i> genes were enriched or introduced quite recently in wastewater treatment facilities.