Degradation of Chloroquine by Ammonia-Oxidizing Bacteria: Performance, Mechanisms, and Associated Impact on N₂O Production

Since the mass production and extensive use of chloroquine (CLQ) would lead to its inevitable discharge, wastewater treatment plants (WWTPs) might play a key role in the management of CLQ. Despite the reported functional versatility of ammonia-oxidizing bacteria (AOB) that mediate the first step for biological nitrogen removal at WWTP (i.e., partial nitrification), their potential capability to degrade CLQ remains to be discovered. Therefore, with the enriched partial nitrification sludge, a series of dedicated batch tests were performed in this study to verify the performance and mechanisms of CLQ biodegradation under the ammonium conditions of mainstream wastewater. The results showed that AOB could degrade CLQ in the presence of ammonium oxidation activity, but the capability was limited by the amount of partial nitrification sludge (∼1.1 mg/L at a mixed liquor volatile suspended solids concentration of 200 mg/L). CLQ and its biodegradation products were found to have no significant effect on the ammonium oxidation activity of AOB while the latter would promote N2O production through the AOB denitrification pathway, especially at relatively low DO levels (≤0.5 mg-O2/L). This study provided valuable insights into a more comprehensive assessment of the fate of CLQ in the context of wastewater treatment

The crosstalk of different functional metabolic and signal transduction pathways that are involved in high temperature tolerance of <i>P</i>. <i>haitanensis</i>.

<p>Red arrows indicate upregulation, green arrows indicate downregulation.</p

Histogram presentation of clusters of orthologous groups (COG) classification of assembled unigenes mapped from contigs of the <i>P</i>. <i>haitanensis</i> transcriptome.

<p>Histogram presentation of clusters of orthologous groups (COG) classification of assembled unigenes mapped from contigs of the <i>P</i>. <i>haitanensis</i> transcriptome.</p

Summary of the <i>P</i>. <i>haitanensis</i> transcriptome.

<p>Summary of the <i>P</i>. <i>haitanensis</i> transcriptome.</p

Expression profiles of differentially expressed genes involved in ubiquitin-mediated proteolysis in the <i>P</i>. <i>haitanensis</i> transcriptome.

<p>1, 2, 3, 4, 5, 6, 7 in the X-axis of different expression diagram represent 0_VS_3h, 0_VS_6h, 0_VS_12h, 0_VS_24h, 0_VS_2d, 0_VS_4d, 0_VS_6d.</p

Gene Ontology (GO) classification of assembled unigenes mapped from contigs of the <i>P</i>. <i>haitanensis</i> transcriptome.

<p>Gene Ontology (GO) classification of assembled unigenes mapped from contigs of the <i>P</i>. <i>haitanensis</i> transcriptome.</p

Enrichment of differentially expressed photosynthesis-related genes in various comparison groups.

<p>‘+’ represents upregulation, and ‘-’ represents upregulation. The numbers between the parentheses represent the total number of upregulated and downregulated genes in the corresponding pathway, respectively.</p

Numbers of differentially expressed unigenes in each comparison.

<p>The numbers on each column show the quantity of up- (blue) and down- (yellow) regulated unigenes.</p

Transcriptomic study to understand thermal adaptation in a high temperature-tolerant strain of <i>Pyropia haitanensis</i>

<div><p><i>Pyropia haitanensis</i>, a high-yield commercial seaweed in China, is currently undergoing increasing levels of high-temperature stress due to gradual global warming. The mechanisms of plant responses to high temperature stress vary with not only plant type but also the degree and duration of high temperature. To understand the mechanism underlying thermal tolerance in <i>P</i>. <i>haitanensis</i>, gene expression and regulation in response to short- and long-term temperature stresses (SHS and LHS) was investigated by performing genome-wide high-throughput transcriptomic sequencing for a high temperature tolerant strain (HTT). A total of 14,164 differential expression genes were identified to be high temperature-responsive in at least one time point by high-temperature treatment, representing 41.10% of the total number of unigenes. The present data indicated a decrease in the photosynthetic and energy metabolic rates in HTT to reduce unnecessary energy consumption, which in turn facilitated in the rapid establishment of acclimatory homeostasis in its transcriptome during SHS. On the other hand, an increase in energy consumption and antioxidant substance activity was observed with LHS, which apparently facilitates in the development of resistance against severe oxidative stress. Meanwhile, ubiquitin-mediated proteolysis, brassinosteroids, and heat shock proteins also play a vital role in HTT. The effects of SHS and LHS on the mechanism of HTT to resist heat stress were relatively different. The findings may facilitate further studies on gene discovery and the molecular mechanisms underlying high-temperature tolerance in <i>P</i>. <i>haitanensis</i>, as well as allow improvement of breeding schemes for high temperature-tolerant macroalgae that can resist global warming.</p></div

Length distribution of all unigenes mapped from contigs of the <i>P</i>. <i>haitanensis</i> transcriptome.

<p>Length distribution of all unigenes mapped from contigs of the <i>P</i>. <i>haitanensis</i> transcriptome.</p