BACKGROUND: With the rapid development of modern industry and agriculture, large amounts of sewage of various types are being discharged into water bodies every year, causing huge environmental pressure and posing a threat to organisms. Amongst different solutions to this problem, microalgae can remove pollutants including pesticides and antibiotics from water. In this work, an algal strain designated as Scenedesmus sp. TXH. was isolated from the Tangxun Lake Sewage Treatment Plant (Wuhan, China) and used to remove imidacloprid (IMI) from sewage. The removal efficiency, degradation products, removal of conventional contaminants [total dissolved nitrogen (TDN) ammonia nitrogen (NH 4 + -N), total dissolved phosphorus (TDP)], the biochemical response of the microalgae, and the effects of environmental factors such as light intensity and temperature were investigated.
RESULTS:The results showed that: (i) the highest IMI removal efficiency of ≈60% was achieved under 80 ∼mol m −2 s −1 at 25 °C;(ii) the removal of NH 4 + -N, TDP and TDN in the sewage reached 90%, 90% and 65%, respectively; (iii) there was a significant linear relationship between the concentration of total chlorophyll and the removal of IMI in the sewage; and (iv) finally, based on the analysis of degradation products by mass spectrometer, three potential IMI degradation pathways were proposed.CONCLUSION: In summary, our results showed that Scenedesmus sp. TXH can remove IMI and conventional nutrients efficiently from sewage, implying a potential application in sewage treatment in the near future.
Probiotic supplementation is a key therapeutic strategy for promoting gut health and maintaining gut homeostasis by modulating functional microbiota. In this study, we isolated two lactic acid bacteria (LAB) strains, Pediococcus pentosaceus TCM-3 and Lacticaseibacillus paracasei TDM-2, from Qinghai-Tibetan plateau, and evaluated their probiotic properties and antioxidant bioactivity. In which, TDM-2 had higher T-AOC activity than either TCM-3 or LGG (4.10 μmol/mL vs. 3.68 and 3.53 μmol/mL, respectively, p < 0.05). These strains have shown high antioxidant activity compared to the LAB strains and were found to be acid and bile salt tolerant, confronting the safety issues of antibiotic resistance and the capability of surviving in simulated gastric and intestinal juices. In vitro fermentation experiments with human gut microbiota revealed significant differences in microbial community composition between samples supplemented with TCM-3 and TDM-2 and those without. The addition of these two strains resulted in an enrichment of beneficial taxa, such as the Pediococcus, Lactobacillus, and Clostridium_sensu_strictos at the genus level, and Firmicutes and Proteobacteria at the phylum level. Notably, the TCM-3 group exhibited higher short-chain fatty acid production than the TDM-2 group and untreated controls (acetic acid at 12 h: 4.54 mmol L−1 vs. 4.06 mmol L−1 and 4.00 mmol L−1; acetic acid at 24 h: 4.99 mmol L−1 vs. 4.90 mmol L−1 and 4.82 mmol L−1, p < 0.05). These findings demonstrate that LAB supplementation with high antioxidant capacity and probiotic properties can promote gut health by modulating functional microbiota and is enriching for beneficial taxa. Our study provides guidance for therapeutic strategies that use novel LAB strains to maintain gut homeostasis and functional microbiota modulation.
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