Bio-degraded of sulfamethoxazole by microbial consortia without addition nutrients: Mineralization, nitrogen removal, and proteomic characterization

Exploring the role of carbon source types in trace-level sulfamethoxazole removal and greenhouse gas emissions in AnMBRs

The efficient removal of trace-level sulfamethoxazole (SMX) from wastewater remains a significant challenge. Different carbon sources can enrich distinct microbiomes, leading to variations in the functional capacity of the community. This makes it possible to select appropriate carbon sources that are conducive to enhancing SMX removal, thereby improving the overall SMX removal efficiency in WWTPs. In this study, acetate, citrate, and glucose were tested as carbon sources in anaerobic membrane bioreactors (AnMBRs) to investigate their effects on trace-level SMX removal. Glucose, as a carbon source, achieved the highest SMX removal efficiency, reduced the risk of resistance gene transmission, and maintained stable nutrient removal performance. The higher abundance of SMX-degrading bacteria and the higher content of extracellular polymeric substances in glucose-fed cultures are the reasons for the higher SMX removal rate. Additionally, GHG emissions, primarily methane, increase with the increase of SMX concentration within the range of 10-250 μg L-1. Methane production is predominantly driven by the acetate-to-methane pathway (M00357 KEGG). Higher SMX concentrations led to an increase in the abundance of SMX-resistant bacteria, causing a large amount of CH4 emissions. These findings provide valuable insights into optimizing carbon source selection and deepen our understanding of the relationship between trace-level SMX removal and GHG emissions in wastewater treatment processes.

Anoxic desulfurization of biogas rich in hydrogen sulfide through feedback control using biotrickling filters: Operational limits and multi-omics analysis

Biodesulfurization is crucial for sustainable biogas purification from hydrogen sulfide (H2S). This study investigates the operational limits of anoxic biotrickling filters (BTFs) for treating biogas with high H2S concentrations (up to 20,000 ppmv) using nitrite, along with simulated interruptions in H2S supply. The BTF achieved a maximum elimination capacity of 312 g S-H2S m-3 h-1 with an H2S removal efficiency of 98 % at an empty bed residence time of 284 s. A proportional-integral-derivative (PID) feedback control system was successfully employed to maintain an H2S outlet concentration close to the requisite setpoint (100 and 500 ppmv) by adjusting the nitrite flow rate, thereby minimizing its accumulation. Continuous nitrite feeding after interruptions in H2S supply was essential to avoid H2S release due to sulfate-reducing bacteria. Multi-omics analyses, combining metagenomics and proteomics, revealed Sulfurimonas as the dominant sulfur-oxidizing bacteria, which downregulates most enzyme genes involved in nitrogen and sulfur metabolism in response to substrate starvation. These findings underscore the resilience of BTFs under extreme conditions and the value of multi-omics approaches in understanding microbial population dynamics, positioning BTFs as a robust solution for large-scale biogas purification.

Construction of a microalgal-fungal spore co-culture system for the treatment of wastewater containing Zn(II) and estrone: Pollutant removal and microbial biochemical reactions

The co-culture system of Chlorella sorokiniana and Aspergillus oryzae has demonstrated exceptional tolerance and efficiency in the removal of pollutants from swine manure. This study evaluates the ability of the co-culture system to remove Zn(II) and estrone, while assessing the impact of these pollutants on the system's overall functionality. Results indicated that co-cultivation achieved higher biomass accumulation, peaking at 0.88 g/L after 96 h. Increasing estrone exposure concentration reduced photosynthetic activity and chlorophyll content, whereas Zn(II) exposure initially enhanced and later inhibited chlorophyll synthesis. Co-cultivation secreted extracellular polymeric substances, including protein-like and humus-like substances, to alleviate environmental stress and form algal-fungal community. After 96 h of cultivation, the removal efficiencies reached 86.44% for 1.5 mg/L Zn(II) and 84.55% for 20 mg/L estrone. The Quantitative Structure Activity Relationship model revealed a reduction in the ecotoxicity of estrone intermediate products to varying degrees. Metabolomics analysis showed that exposure to estrone and Zn(II) significantly boosted the production of Gibberellic acid, Indole-3-acetic acid, and Zeatin riboside in Chlorella sorokiniana, while reducing Abscisic Acid levels. Furthermore, the exposure led to an increase in various metabolites in the Tricarboxylic acid cycle of the co-cultivation system, influencing the synthesis and metabolism of key biochemical components like carbohydrates, lipids, and proteins. These findings elucidate the biochemical responses of Chlorella sorokiniana-Aspergillus oryzae co-culture system to pollutants and provide insights into its potential application in the treatment of wastewater containing endocrine disrupting chemicals and heavy metals.

Microbes as Resources to Remove PPCPs and Improve Water Quality

The inadequate removal of pharmaceuticals and personal care products (PPCPs) by traditional wastewater treatment plants (WWTPs) poses a significant environmental and public health challenge. Residual PPCPs find their way into aquatic ecosystems, leading to bioaccumulation in aquatic biota, the dissemination of antibiotic resistance genes (ARGs), and contamination of both water sources and vegetables. These persistent pollutants can have negative effects on human health, ranging from antibiotic resistance development to endocrine disruption. To mitigate these risks, there is a growing interest in exploiting microorganisms and their enzymes for bioremediation purposes. By harnessing the metabolic capabilities of microbial communities, PPCPs can be efficiently degraded, transformed, or sequestered in water systems. Additionally, microbial communities exhibit remarkable adaptability and resilience to diverse PPCP contaminants, further underscoring their potential as sustainable and cost-effective solutions for water treatment. This review explores the promise of microbial bioremediation as an approach to addressing the complex challenges posed by persistent PPCP contamination, emphasising its potential to safeguard both environmental integrity and human well-being.

Co-metabolism of microorganisms: A study revealing the mechanism of antibiotic removal, progress of biodegradation transformation pathways

The widespread use of antibiotics has resulted in large quantities of antibiotic residues entering aquatic environments, which can lead to the development of antibiotic-resistant bacteria and antibiotic-resistant genes, posing a potential environmental risk and jeopardizing human health. Constructing a microbial co-metabolism system has become an effective measure to improve the removal efficiency of antibiotics by microorganisms. This paper reviews the four main mechanisms involved in microbial removal of antibiotics: bioaccumulation, biosorption, biodegradation and co-metabolism. The promotion of extracellular polymeric substances for biosorption and extracellular degradation and the regulation mechanism of enzymes in biodegradation by microorganisms processes are detailed therein. Transformation pathways for microbial removal of antibiotics are discussed. Bacteria, microalgae, and microbial consortia's roles in antibiotic removal are outlined. The factors influencing the removal of antibiotics by microbial co-metabolism are also discussed. Overall, this review summarizes the current understanding of microbial co-metabolism for antibiotic removal and outlines future research directions.

Effects of sulfamethoxazole and copper on the natural microbial community from a fertilized soil

Cattle manure or its digestate, which often contains antibiotic residues, can be used as an organic fertilizer and copper (Cu) as a fungicide in agriculture. Consequently, both antibiotics and Cu are considered soil contaminants. In this work, microcosms were performed with soil amended with either manure or digestate with Cu and an antibiotic (sulfamethoxazole, SMX) co-presence and the planting of Lactuca sativa. After the addition of the organic amendments, a prompt increase in the microbial activity and at the same time of the sul1 and intI1 genes was observed, although ARGs generally decreased over time. In the amended and spiked microcosms, the microbial community was able to remove more than 99% of SMX in 36 days and the antibiotic did not bioaccumulate in the lettuce. Interestingly, where Cu and SMX were co-present, ARGs (particularly sul2) increased, showing how copper had a strong effect on resistance persistence in the soil. Copper also had a detrimental effect on the plant-microbiome system, affecting plant biomass and microbial activity in all conditions except in a digestate presence. When adding digestate microbial activity, biodiversity and lettuce biomass increased, with or without copper present. Not only did the microbial community favour plant growth, but lettuce also positively influenced its composition by increasing bacterial diversity and classes (e.g., Alphaproteobacteria) and genera (e.g., Bacillus), thus indicating a good-quality soil. KEY POINTS: • Cattle digestate promoted the highest microbial activity, diversity, and plant growth • Cattle digestate counteracted detrimental contaminant effects • Cu presence promoted antibiotic cross-resistance in soil.