Metabolic Effects of Sucralose on Environmental Bacteria

Sucralose was developed as a low cost artificial sweetener that is nonmetabolizable in humans. Sucralose can withstand changes in pH and temperature and is not degraded by the wastewater treatment process. Since the molecule can withstand heat, acidification, and microbial degradation, it is accumulating in the environment and has been found in wastewater, estuaries, rivers, and the Gulf Stream. Environmental isolates were cultured in the presence of sucralose looking for potential sucralose metabolism or growth acceleration responses. Sucralose was found to be nonnutritive and demonstrated bacteriostatic effects on all six isolates. This growth inhibition was directly proportional to the concentration of sucralose exposure, and the amount of the growth inhibition appeared to be species-specific. The bacteriostatic effect may be due to a decrease in sucrose uptake by bacteria exposed to sucralose. We have determined that sucralose inhibits invertase and sucrose permease. These enzymes cannot catalyze hydrolysis or be effective in transmembrane transport of the sugar substitute. Current environmental concentrations should not have much of an effect on environmental bacteria since the bacteriostatic effect seems to be consecration based; however, as sucralose accumulates in the environment, we must consider it a contaminant, especially for microenvironments. 1. Introduction Sucralose was the first noncalorie sweetener made from natural sugar, being manufactured by the selective chlorination of sucrose, which substitutes three of the hydroxyl groups with chlorines [1]. Sucralose is stable under increased heat and over a broad range of acidic and alkaline conditions. Therefore, sucralose can be used in baking or in products that require a longer shelf-life [2]. Sucralose causes exactly zero caloric increase in mammals [1]. Artificial sweeteners have been considered contaminants by environmental scientists only recently [3]. Due to the human inability to metabolize these molecules, they are passed on to the environment via human excrement, and the highest concentration (2,800 ± 1,000？ng/L) of combined artificial sweetener contaminants is found in wastewater treatment reservoirs [4]. Artificial sweeteners such as saccharin and cyclamates are found mostly degraded by the wastewater treatment process. Sucralose, however, is found in higher concentrations and was degraded minimally [4]. Degradation only occurs to a limited extent during hydrolysis, ozonation, and microbial processes indicating that breakdown of sucralose will likely be slow and incomplete