Lake Chaohu, which is a large, shallow, hypertrophic freshwater lake in southeastern China, has been experiencing lake-wide toxic Microcystis blooms in recent decades. To illuminate the relationships between microcystin (MC) production, the genotypic composition of the Microcystis community and environmental factors, water samples and associated environmental data were collected from June to October 2012 within Lake Chaohu. The Microcystis genotypes and MC concentrations were quantified using quantitative real-time PCR (qPCR) and HPLC, respectively. The results showed that the abundances of Microcystis genotypes and MC concentrations varied on spatial and temporal scales. Microcystis exists as a mixed population of toxic and non-toxic genotypes, and the proportion of toxic Microcystis genotypes ranged from 9.43% to 87.98%. Both Pearson correlation and stepwise multiple regressions demonstrated that throughout the entire lake, the abundances of total and toxic Microcystis and MC concentrations showed significant positive correlation with the total phosphorus and water temperature, suggesting that increases in temperature together with the phosphorus concentrations may promote more frequent toxic Microcystis blooms and higher concentrations of MC. Whereas, dissolved inorganic carbon (DIC) was negatively correlated with the abundances of total and toxic Microcystis and MC concentrations, indicating that rising DIC concentrations may suppress toxic Microcystis abundance and reduce the MC concentrations in the future. Therefore, our results highlight the fact that future eutrophication and global climate change can affect the dynamics of toxic Microcystis blooms and hence change the MC levels in freshwater.

Microcystis blooms have become a ubiquitous phenomenon in freshwater ecosystems, and the size of Microcystis colonies varies widely throughout the year. In the present study, hydrogen peroxide (H₂O₂) was applied to test the effect of this algaecide on Microcystis colonies of different sizes and to evaluate the colonies' antioxidant strategy. The results showed that Microcystis populations collapsed under treatment with 5 mg/L H₂O₂ at colony sizes smaller than 25 μm. A dosage of 20 mg/L H₂O₂ was necessary to efficiently control Microcystis colonies larger than 25 μm. The enzymatic and non-enzymatic antioxidant systems of different colonies exhibited various strategies to mitigate oxidative stress. In small colonies, superoxide dismutase (SOD) activity was readily stimulated and operated with catalase (CAT) activity to eliminate reactive oxygen species (ROS). In colonies larger than 25 μm, the antioxidant enzyme CAT and antioxidant substance glutathione (GSH) played major roles in mitigating oxidative stress at H₂O₂ concentrations below 20 mg/L. In addition, application of the algaecide led to the release of intracellular-microcystins (MCs), and oxidatively-driven MCs reached high concentrations when colony size was larger than 100 μm. Algaecide control measures should be implemented before the formation of large colonies to limit the algaecide dosage and MC release.

Under the background of carbon neutrality, the constructed wetland-microbial fuel cell coupled system (CW-MFC) has attracted more and more attention in wastewater treatment. This study, the CW-MFC was developed for promoting nutrients removal in wastewater and electricity generation. The results showed that the average removal efficiencies of COD, NH₄⁺-N and TP in CW-MFC were 85.20%, 75.99% and 59.20%, respectively. While the average removal efficiencies of COD, NH₄⁺-N and TP in CW were 78.05%, 70.88% and 50.80%, which were all lower than those in CW-MFC. In addition, the maximum output voltage of 331 mV was achieved in CW-MFC, which could be used for the running of wastewater treatment plant in turn and further reduce the consumption of fossil fuel. Accordingly, the maximum power density of the CW-MFC system reached to 107.54 mW m^-3.

The expression of Pib gene in rice was induced by hormone, such as jasmonic acid and ethylene. In order to determine the necessary regions of sequence or motifs for response to jasmonic acid and ethylene in Pib promoter, the full length promoter of Pib (-3,572 approximately 2 bp) and three different 5' deletion fragments of Pib promoter (-2,692 approximately 2 bp, -1,335 approximately 2 bp, -761 approximately 2 bp) were synthesized by PCR and then were substituted for 35S upstream gus in a binary plasmid to construct re-combined plasmids of Pib promoter-gus fusions. Transgenic rice plants of the four recombined plasmids were produced by Agrobacterium-mediated transformation. Quality and quantum analysis of gus activities in transgenic plants at both protein and mRNA levels were conducted. The promotion activity of the full length promoter of Pib (-3,572 approximately 2 bp, pNAR901) was the highest in the four recombinants and the gus activities in its transgenic plant organs were enhanced obviously at 6 h after treatment with jasmonic acid or ethylene. The promotion activity of the deleted Pib promoters was significantly decreased and the response to jasmonic acid or ethylene treatment was not present when the -3,572 approximately -2,692 bp sequence was knocked out from the Pib promoter. Although the disparity in the lengths of the deleted Pib promoter of pNAR902 (-2,692 approximately 2 bp), pNAR903 (-1,335 approximately 2 bp), and pNAR904 (-761 approximately 2 bp) was more than 2 or 3 times, the response to jasmonic acid or ethylene treatment was not different among their transgenic plants. All these results indicated that the common deleted sequences (-3,572 approximately -2,692 bp) in the three deleted Pib promoter constructs were the essential region to the response to jasmonic acid and ethylene treatment. The result of pib promoter sequence searching indicated that there was only one GCCGCC motif at -2,722 bp of this common deleted segment in the Pib promoter sequence. Our rice transgenic results showed that the GCCGCC may be a cis-motif for Pib gene conferring response to jasmonic acid and ethylene for Pib gene.

To clarify the effects of nutrient addition on algal growth during the early stages of phytoplankton bloom, an microcosm experiment was conducted in early spring; it included two groups of in situ samples: sediment plus lake water (S+W), representing the nominal “control”, and sediment plus 50% BG11 medium and 50% lake water (S+BW), representing the treatment of nutrient addition. The results demonstrated the recruitment biomass of non-cyanobacteria in the treatment group was about 46.7% of that in the control group, and the recruitment biomass of cyanobacteria in the treatment group was approximately 5 times than that in the control. After recruitment, nutrient addition generated remarkable stimulation of the growth of all algae, especially cyanobacteria. The results suggested that the stimulation by nutrient addition of algal growth after recruitment may be responsible for the occurrence of phytoplankton blooms, and the more pronounced promotion of cyanobacteria than non-cyanobacteria was explainable for the strengthening of the dominance of cyanobacteria during eutrophication.