Artificial Sweeteners in Pig Feed: A Worldwide Survey and Case Study in Pig Farms in Tianjin, China

Taste traces: Capsaicin and sweeteners as anthropogenic markers in municipal wastewater

Dietary-derived substances possess significant potential as anthropogenic markers owing to the large consumption and different intake habit. To investigate and evaluate such markers, wastewater samples from 35 wastewater treatment plants across 29 Chinese cities were collected to analyze artificial sweeteners (acesulfame and cyclamate) and natural spicy compounds (capsaicin and dihydrocapsaicin). Acesulfame (mean: 14.6 μg/L), cyclamate (mean: 24.3 μg/L), and capsaicin (mean: 101 ng/L) can be further investigated as anthropogenic markers due to their high detection frequency at high concentrations. Spatial use patterns revealed that acesulfame (5.31 g/d/1000 inhabitants (inh)) and cyclamate (8.16 g/d/1000 inh) use in northern China notably surpassed that in southern China (1.79 g/d/1000 inh and 3.23 g/d/1000 inh, p < 0.05). Conversely, chili pepper use was significantly higher (p < 0.05) in southern China (6702 g/d/1000 inh) than in northern China (2751 g/d/1000 inh), signifying a preference for sweetness in the northern regions and a predilection for spiciness in the southern regions. The total annual use of acesulfame (1842 t), cyclamate (3110 t), and chili (18.4 million tonnes) in China was estimated by this study, which was close to the national statistical production. In addition, sweetener use was negatively associated with the elderly population ratio, suggesting that the elderly population might not consume sweet foods. This study reveals the dietary sources of anthropogenic markers, highlighting the need for further research on the environmental implications of such markers.

Artificial Sweetener Enhances the Spread of Antibiotic Resistance Genes During Anaerobic Digestion

Artificial sweeteners have been frequently detected in the feedstocks of anaerobic digestion. As these sweeteners can lead to the shift of anaerobic microbiota in the gut similar to that caused by antibiotics, we hypothesize that they may have an antibiotic-like impact on antibiotic resistance genes (ARGs) in anaerobic digestion. However, current understanding on this topic is scarce. This investigation aimed to examine the potential impact of acesulfame, a typical artificial sweetener, on ARGs in anaerobic digestion by using metagenomics sequencing and qPCR. It was found that acesulfame increased the number of detected ARG classes and the abundance of ARGs during anaerobic digestion. The abundance of typical mobile genetic elements (MGEs) and the number of potential hosts of ARGs also increased under acesulfame exposure, suggesting the enhanced potential of horizontal gene transfer of ARGs, which was further confirmed by the correlation analysis between absolute abundances of the targeted ARGs and MGEs. The increased horizontal dissemination of ARGs may be associated with the SOS response induced by the increased ROS production, and the increased cellular membrane permeability. These findings indicate that artificial sweeteners may accelerate ARG spread through digestate disposal, thus corresponding strategies should be considered to prevent potential risks in practice.

Use of artificial sweeteners and caffeine in a population of Hanoi: An assessment by wastewater-based epidemiology

Monitoring the consumption of artificial sweeteners in the population is essential to help public health authorities understand the level of sugar consumption. There is a gap in knowledge of patterns and levels of artificial sweetener consumption in Vietnam. Using wastewater-based epidemiology (WBE), this study aims to evaluate the use of artificial sweeteners in an urban population in Hanoi, Vietnam. A total of 184 wastewater samples were collected at two sampling sites in an urban canal, receiving sewage from over 400,000 people in three different periods between 2018 and 2020. The population normalized per capita consumption of the five detected artificial sweeteners varied from 0.87 mg d^-1 p^-1 (sucralose) to 5.2 mg d^-1 p^-1 (aspartame). The daily consumption of artificial sweeteners was found to be stable throughout the week, however the consumption of artificial sweeteners was influenced by season with higher consumption in summer. Significant correlations (p < 0.01) were found among levels of artificial sweeteners and caffeine in urban canal samples, suggesting these chemicals had common sources. Population-weighted consumption load of artificial sweeteners and caffeine was compared in Vietnam, China and Australia, and the per capita consumption load mainly depended on the habitual of tea/coffee drinking in different countries. This was the first study that provided information on the artificial sweetener consumption by wastewater analysis in Vietnam. However, several sources of uncertainty (sample collection, population estimation, other sources of artificial sweeteners in wastewater, etc.) were acknowledged in this study. Further investigations on the spatial-temporal variation of artificial sweetener consumption with more intensive sampling scheme in Vietnam are recommended.

Assessing Nursery-Finishing Pig Manures on Growth of Black Soldier Fly Larvae

Livestock manure is an important component of agricultural organic waste, and in recent years, with the development of research on the bioconversion of manure, BSFs have been proven to be useful in the treatment of a variety of livestock wastes. In-depth research on the composition of manure and its effect on the development of BSFL is, however, very scarce. The purpose of this study was to identify the parameters that influenced the growth of BSFL that was fed fattening pig manure. The pH, moisture, and nutrients of the fattening manures (namely, nursery, growing, and finishing pig manures) were measured. To examine the influence of manure types on larval growth, 100 larvae were inoculated in 100 g of each type of manure in triplicate. According to the findings, larvae fed finishing pig manure had the lowest dry weight (30.2 ± 6.1 mg) compared to those fed growing (58.2 ± 7.3 mg) or nursery (65.5 ± 6.2 mg) pig manure. The correlation coefficients (r) between the nutrients in the manure and the weight of the larvae were calculated. Hemicellulose had the greatest |r| value (0.9569). Further research revealed that larvae raised on hemicellulase-pretreated finishing pig manure frequently weighed 21-30% (days 2-8) more than larvae raised on control manure. In conclusion, hemicellulose was a significant component that might hinder larval growth. The results of this study could be used to improve the system before it is put into use.

Young population consume twice as much artificial sweetener than the general population - A wastewater-based assessment in China

Understanding artificial sweetener consumption patterns and levels in different demographics is important for formulating public health policies on controlling sugar consumption. There is a considerable knowledge gap with respect to the pattern of artificial sweetener consumption in China. To narrow this gap, wastewater analysis was used to assess the temporal patterns of consumption of seven artificial sweeteners in an urban population and a university town in a megacity in South China over a one-year period. Daily influent wastewater samples were collected from an urban catchment and weekly samples collected from a university sub-catchment. Population normalized per capita consumption of the four detected artificial sweeteners (cyclamate, acesulfame, sucralose and saccharin) in the university catchment (1.0-5.9 mg d^-1 p^-1) was much higher than those in urban catchment (0.5-1.3 mg d^-1 p^-1), indicating younger population consume more artificial sweeteners than the general population. The daily consumption of artificial sweeteners was found to be stable throughout the week in the urban catchment. Time-series analysis showed that an average increase in temperature of 1 °C was associated with an increase consumption of 33 μg d^-1 p^-1 for acesulfame, 15 μg d^-1 p^-1 for sucralose and 14 μg d^-1 p^-1 for saccharin. This was the first study that objectively quantified the greater consumption of artificial sweeteners (proxy for consumption of artificially sweetened food and beverages) in a younger age group when compared to the general population, which could potentially pose a risk of health related diseases.

Extra benefit of microalgae in raw piggery wastewater treatment: pathogen reduction

BACKGROUND

Monitoring microbial communities especially focused on pathogens in newly developed wastewater treatment systems is recommended for public health. Thus, we investigated the microbial community shift in a pilot-scale microalgal treatment system for piggery wastewater.

RESULTS

Microalgae showed reasonable removal efficiencies for COD and ammonia, resulting in higher transparency of the final effluent. Metagenome and microbial diversity analyses showed that heterotrophic microalgal cultivation barely changed the bacterial community; however, the mixotrophic microalgal cultivation induced a sudden change. In addition, an evaluation of risk groups (RGs) of bacteria showed that raw piggery wastewater included abundant pathogens, and the microalgal treatment of the raw piggery wastewater decreased the RG2 pathogens by 63%. However, co-cultivation of microalgae and the most dominant RG2 pathogen, Oligella, showed no direct effects between them.

CONCLUSIONS

Thus, a microbial interaction network was constructed to elucidate algae-bacteria interrelationships, and the decrease in Oligella was indirectly connected with microalgal growth via Brevundimonas, Sphingopyxis, and Stenotrophomonas. In a validation test, 3 among 4 connecting bacterial strains exhibited inhibition zones against Oligella. Therefore, we showed that microalgal wastewater treatment causes a decrease in RG2 bacteria, which is an indirect impact of microalgae associated with bacteria. Video abstract.

Non-caloric artificial sweeteners exhibit antimicrobial activity against bacteria and promote bacterial evolution of antibiotic tolerance

Non-caloric artificial sweeteners are being widely used as safe table sugar substitutes with highly intensive sweetness but low calories. Previous studies have suggested that some of the sweeteners can alter the gut microbiota composition and promote horizontal transfer of antibiotic resistance genes across bacterial genera. However, little is known about whether these sweeteners could show antibiotic-like antimicrobial activity against bacteria, especially gut relevant bacteria. Whether they could affect evolutional trajectory of antibiotic resistance or tolerance in bacteria is also not clear yet. Here we investigated four commonly used artificial sweeteners (saccharin, sucralose, aspartame, and acesulfame potassium) against both Gram-negative (Escherichia coli and Klebsiella pneumoniae) and positive (Bacillus subtilis) strains. Results show that all four sweeteners exhibit antimicrobial effects on these strains. The antimicrobial mechanism is due to increased reactive oxygen species (ROS) and cell envelope damage. Compared to sucrose and glucose, the treatment of artificial sweeteners stimulates bacterial efflux pumps and promotes bacterial evolution of antibiotic tolerance. Collectively, our finding provides insights into roles of artificial sweeteners in the emergence of antibiotic tolerance and calls for a re-evaluation of risks due to their intensive usage.

Enhancement of antibiotic resistance dissemination by artificial sweetener acesulfame potassium: Insights from cell membrane, enzyme, energy supply and transcriptomics

The abuse of antibiotics on animals could induce the development of antibiotic resistant genes (ARGs) and antibiotic resistant bacteria (ARB), and acesulfame potassium (ACE) is the widely used artificial sweetener in animal feed. Generally speaking, ACE and ARB often coexist in livestock wastewater, however, the impact of the co-occurrence of ACE and ARB on the transmission of ARGs is still unknown. In this study, the effects of ACE on vertical gene transfer (VGT) and horizontal gene transfer (HGT) were both evaluated. For VGT, ACE may hinder the spread of sul gene in Pseudomonas HLS-6 by blocking ARB growth. As for HGT (from Escherichia coli DH5α to Pseudomonas HLS-6), environmentally relevant ACE concentration could facilitate the conjugative transfer. The underlying mechanisms of HGT were characterized by enhanced cell membrane permeability, reactive oxygen species overproduction, SOS response, energy supply, which were all further verified by the changes in transcription levels of related genes. Interestingly, intracellular Mg²⁺ in donor strain was found for the first time as an indicator for the conjugation occurrence in ACE treated mating system. This study may provide new insights into the role of ACE on ARGs proliferation and highlight its potential environmental impacts.

Artificial sweeteners stimulate horizontal transfer of extracellular antibiotic resistance genes through natural transformation

Antimicrobial resistance has emerged as a global threat to human health. Natural transformation is an important pathway for horizontal gene transfer, which facilitates the dissemination of antibiotic resistance genes (ARGs) among bacteria. Although it is suspected that artificial sweeteners could exert antimicrobial effects, little is known whether artificial sweeteners would also affect horizontal transfer of ARGs via transformation. Here we demonstrate that four commonly used artificial sweeteners (saccharin, sucralose, aspartame, and acesulfame potassium) promote transfer of ARGs via natural transformation in Acinetobacter baylyi ADP1, a model organism for studying competence and transformation. Such phenomenon was also found in a Gram-positive human pathogen Bacillus subtilis and mice faecal microbiome. We reveal that exposure to these sweeteners increases cell envelope permeability and results in an upregulation of genes encoding DNA uptake and translocation (Com) machinery. In addition, we find that artificial sweeteners induce an increase in plasmid persistence in transformants. We propose a mathematical model established to predict the long-term effects on transformation dynamics under exposure to these sweeteners. Collectively, our findings offer insights into natural transformation promoted by artificial sweeteners and highlight the need to evaluate these environmental contaminants for their antibiotic-like side effects.

Tracking the fate of artificial sweeteners within the coastal waters of Shenzhen city, China: From wastewater treatment plants to sea

Artificial sweeteners (ASs), as a new emerging pollutant, the fate from wastewater treatment plants (WWTPs) to sea is growing concerned. In this study, the distribution and polluted loading of six typical ASs were analyzed based on the measurement in influent, primary effluent, secondary effluent, tertiary effluent, suspended particulate matter (SPM), and sludge from four WWTPs and receiving waters near the coast of Shenzhen city, China. Elevated levels of ASs were detected in WWTPs located near a highly populated area (about 14,000 people km^-2). Sucralose was predominant in all water samples (0.1-22.2 μg L^-1), and had a 1.6-704.0 times higher concentration than the means of other ASs detected. Aspartame were mainly distributed in SPM and sludge, and the fractions in offshore water exceeded 45%. Acesulfame, sucralose, cyclamate and saccharin could be effectively removed by secondary biochemical treatment. The average daily loading (4.2 g d^-1 1000people^-1) and discharge loading (0.4 g d^-1 1000people^-1) of sucralose in WWTPs was higher than those of the other ASs. Dissolved organic carbon and UV₂₅₄ can affect the fate of ASs, and SPM mainly affects the distributions of aspartame and neotame. As a potential sewage indicator, neotame deserves further attention.

Aqueous degradation of artificial sweeteners saccharin and neotame by metal organic framework material

The artificial sweeteners (ASs) saccharin (SAC) and neotame (NEO) are widely used across the globe and are considered as emerging contaminants in surface, ground, and drinking waters. To degrade SAC and NEO, the metal organic framework material Co-based bio-MOF-11 was prepared by hydrothermal reaction and used with peroxymonosulfate (PMS) activator. The effects of the initial concentration of SAC and NEO, bio-MOF-11-Co dosage, PMS concentration, initial pH, temperature, and competitive anions were determined. The results revealed that bio-MOF-11-Co effectively catalyzed the degradation of SAC and NEO and possessed good stability and recycling efficiency. The degradation reaction was effective from pH 3.6-9.8 and followed quasi-first-order kinetics with degradation rate constants of 0.001-0.013 min^-1 for SAC and 0.03-0.52 min^-1 for NEO. Increased temperature was conducive to the degradation of both artificial sweeteners. The presence of Cl^- inhibited the degradation of SAC and NEO, while the presence of CO₃^2- promoted their degradation. Electron paramagnetic resonance (EPR) and free radical quenching demonstrated that the primary free radicals were sulfate radicals ( [Formula: see text] ) and hydroxyl radicals (HO). The change of cobalt oxidation state and electron transfer in bio-MOF-11-Co mainly induces the production of [Formula: see text] . A plausible mechanism for degradation is [Formula: see text] and HO attack on CS bonds, NS bonds, and benzene rings.

Emission and Mass Load of Artificial Sweeteners from a Pig Farm to Its Surrounding Environment: Contribution of Airborne Pathway and Biomonitoring Potential

An investigation was conducted by determining artificial sweeteners (ASs) in 80 samples from various environmental matrices, including dry deposition, rainfall, soil, leaf, and bark samples around a pig farm in Tianjin, China. Saccharin, cyclamate, and acesulfame were predominant in dry deposition and rainfall samples. Spatially, the distribution of ASs showed a consistent trend of farm center > downwind sites > upwind sites > reference site. The annual total mass loads of saccharin (70%), cyclamate (25%), and acesulfame (5%) via dry deposition and precipitation within a 5 km radius of the pig farm were estimated at 3.9 and 6.2 kg in the average-case and worst-case scenarios, respectively, accounting for 12-18% of the overall emission, indicating that pig farms are a significant source of ASs to the atmosphere and to the vicinal environment via dry and wet deposition. The distribution trends of ASs in tree bark and leaves were similar and tree bark performed better in passively biomonitoring the AS contamination. Overall, pig farms were predicted to release 65-114, 22-38, 2.0-3.5, and 0.6-1.1 tons by feed application in China, Europe, Latin America, and North America, respectively, to the vicinal environment via dry deposition and precipitation.