6%-19.8% and 3.9%-36.0%, respectively, thus resulting in a lack of essential trace elements or pollution of heavy metals; hence, the impact of O3 on rice food quality and safety requires a comprehensive evaluation.The ammonia oxidation process is a rate-limiting step in nitrification. Ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) are the major drivers of ammonia oxidation. Their distribution and relative contributions to nitrification are the research highlights in the nitrogen cycle. Real-time quantitative polymerase chain reaction (qPCR) was used to study the distribution of aerobic ammonia-oxidizing microorganisms in the surface sediments of mangrove in the Sanya River, and the relative contribution rates of AOB and AOA to nitrification were calculated through the determination of the potential nitrification rates (PNR). The results showed that, in most sampling sites, the abundance of AOA amoA genes was higher than that of AOB amoA genes. The abundance of AOB was higher during the winter, whereas that of AOA was higher during the summer, and the ratio of AOA to AOB abundance was lower during the winter. The dissolved oxygen (DO) content, pH, total organic carbon (TOC) content, and nitrate concentration greatly influenced the abundance of AOB and AOA. The potential nitrification rates of AOB and AOA were both higher during the summer than during the winter, and the relative contribution rate of AOA to nitrification was higher during the winter, whereas that of AOB was higher during the summer. There were no significant correlations between the PNR and amoA genes abundance of AOB and AOA.Mn(Ⅱ)-oxidizing microorganisms can catalytically increase the oxidation rate of divalent manganese by several orders of magnitude, and affect the valence state and fate of elemental manganese. In addition to Mn(Ⅱ)-oxidization by a single microbial strain, our previous studies revealed that interspecies interactions between two bacterial strains (Sphingopyxis sp. QXT-31 and Arthrobacter sp. QXT-31) could trigger the Mn(Ⅱ)-oxidizing activities of Arthrobacter sp. QXT-31.  https://www.selleckchem.com/products/su5402.html  In order to further explore its universality, mechanism, and potential engineering applications, research was conducted on three other Sphingopyxis strains using culture-dependent experiments, comparative genomic analysis, and transcriptome analysis. The results showed that one Sphingopyxis strain could also trigger the Mn(Ⅱ)-oxidizing activity of Arthrobacter sp. QXT-31, which could be regarded as a hint for the prevalence of Mn(Ⅱ) oxidation triggered by microbial interspecies interactions in the natural environment. Furthermore, the upregulation of the antibiotic synthesis pathway in Sphingopyxis was observed just before the Mn(Ⅱ)-oxidizing activity of Arthrobacter sp. QXT-31 was triggered, thus suggesting its possible involvement in stimulating the Mn(Ⅱ)-oxidizing activity of Arthrobacter sp. QXT-31. Finally, we demonstrated that using microbial interspecies interactions to enhance the oxidative removal of Mn(Ⅱ) in a manganese removal reactor is potentially feasible.In order to further understand the influence of high temperature shock on the microbial community structure of activated sludge during the process of nitrite oxidation, the enriched nitrifying activated sludge under different NO2--N concentration was taken as the research object in this study. 16S rRNA high-throughput sequencing technology was used to analyze the changes in the microbial community abundance and structural characteristics of activated sludge by changing the environmental temperature. The results of high-throughput sequencing showed that microorganisms were more likely to grow at 25℃, and the diversity of the microbial community in the activated sludge was the most abundant. With increased temperature, the richness, evenness, and diversity of the flora in the system decreased. In addition, it was found that the main nitrifying bacterium in the system was Nitrospira of Nitrospirae, whereby 35℃ was more suitable for its growth. Meanwhile, a higher temperature also caused differences in the structure of non-nitrifying functional microorganisms (e.g., Bacteroidetes, Chlorofulexi, Halomonas, and Pseudomonas) in the activated sludge. The results of this study provide some theoretical reference for the investigation of the distribution characteristics of microbial flora during the process of nitrite oxidation under high temperature shock, and can also be used as reference for relevant high temperature shock tests.The effective inhibition of nitrite oxidizing bacteria (NOB) is the key to realizing satisfactory nitrite accumulation and achieving effective nitritation. In order to explore the selective effect of hydroxylamine (NH2 OH) on ammonia oxidizing bacteria (AOB) and NOB, a sequencing batch reactor (SBR) with the operation mode of anaerobic/aerobic/anoxia (A/O/A) was used to observe the start-up of nitritation at different concentrations and frequencies of NH2 OH. The results showed that when 5 mg·L-1 of NH2 OH was added once every 2 cycles, the nitrite accumulation rate (NAR) increased from 0.1% to 57.4% in 6 days, and was maintained at (62.0±4.6)% until the end of the trials. In the typical cycle on day 6, the NN4+-N dropped from 26.05 mg·L-1 to 8.06 mg·L-1, thus producing 9.02 mg·L-1 of NO2--N and 6.70 mg·L-1 of NO3--N. Meanwhile, the ratio of the maximum activity of AOB (rAOB) to NOB (rNOB) increased from 1.05 on day 1 to 4.22 on day 9. Moreover, qPCR results indicated that the abundance of AOB and NOB decreased to 30.2% and 19.1%, respectively, on day 9 in comparison to the original sample. The results indicate that the selective effect of AOB and NOB based on NH2 OH is expected to provide a feasible application for the rapid start-up nitritation of municipal wastewater.The tetracycline (TC) antibiotic has been widely found in different environmental matrices. The tetracycline resistant bacterium (TRB) of Shigella flexneri was screened and purified from activated sludge, and was then used to study the impact of TC stress on the gene abundances and expression levels of TC resistance genes (TC-ARGs), including tetC, tetO, and tetX, which were respectively quantified by quantitative PCR and reverse transcriptional PCR. Correlations between the TC concentration and gene abundances of TC-ARGs and their expression levels were discussed. The results showed that TC stress had an inhibiting effect on the growth of Shigella flexneri during the entire culture cycle (24 h) and that the growth rate of the bacterial concentration decreased with increasing TC concentration. However, less impact on the gene abundance of TC-ARGs was found. TC stress could promote the expression of TC-ARGs in Shigella flexneri, and the expression levels of tetC, tetO, and tetX genes first increased and then decreased.