Sated by a Zero-Calorie Sweetener: Wastewater Bacteria Can Feed on Acesulfame

Abstract

The widely used artificial sweetener acesulfame K has long been considered recalcitrant in biological wastewater treatment. Due to its persistence and mobility in the aquatic environment, acesulfame has been used as marker substance for wastewater input in surface water and groundwater. However, recent studies indicated that the potential to remove this xenobiotic compound is emerging in wastewater treatment plants worldwide, leading to decreasing mass loads in receiving waters despite unchanged human consumption patterns. Here we show evidence that acesulfame can be mineralized in a catabolic process and used as sole carbon source by bacterial pure strains isolated from activated sludge and identified as Bosea sp. and Chelatococcus sp. The strains mineralize 1 g/L acesulfame K within 8–9 days. We discuss the potential degradation pathway and how this novel catabolic trait confirms the “principle of microbial infallibility.” Once the enzymes involved in acesulfame degradation and their genes are identified, it will be possible to survey diverse environments and trace back the evolutionary origin as well as the mechanisms of global distribution and establishment of such a new catabolic trait.

Effect of concentration and hydraulic reaction time on the removal of pharmaceutical compounds in a membrane bioreactor inoculated with activated sludge

“…Furthermore, evolution seems to be slow due to low concentrations and complexity in chemical structures. Recently, two studies described a putative evolution of acesulfame degradation in WWTPs all around the world (Kahl et al ., 2018; Kleinsteuber et al ., 2019). Acesulfame was considered recalcitrant in WWTPs until 2014, when several studies started to observe good biodegradation of this compound.…”

A Review of the Environmental Fate and Effects of Acesulfame‐Potassium

“…It appears that if the WWTP operating conditions are suitable, including mesophilic temperature ranges and perhaps longer retention times, there may be an emerging trend for the biodegradation of ACE‐K in WWTPs worldwide. Following up on these emerging findings, Kleinsteuber et al (2019) have recently provided additional preliminary mechanistic evidence that ACE‐K can be mineralized in a catabolic process and used as the sole C source by pure strains of bacteria isolated from activated sludge. Three slow‐growing strains of ACE‐K biodegraders were isolated and degraded 1 g/L ACE‐K within 8 to 9 d.…”

Effect of concentration and hydraulic reaction time on the removal of pharmaceutical compounds in a membrane bioreactor inoculated with activated sludge

“…Since then more reports showed the decent removal of this compound in WWTPs. In follow-up studies, microorganisms able to use acesulfame as carbon source were isolated (Kahl et al, 2018;Kleinsteuber et al, 2019). This example demonstrates the on-going adaptation of microorganisms towards OMP biodegradation in WWTPs.…”