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Biofilms attached to submerged macrophytes play an important role in improving the water quality of the water environment supplemented with reclaimed water. In order to explore the effects of reclaimed water quality and submerged macrophyte species on the characteristics of an epiphytic bacterial community, different types of submerged macrophytes were selected as research objects in this study. 16S rRNA high-throughput sequencing technology was used on the epiphytic bacteria and the surrounding environmental samples to analyze the bacterial community structure and functional genes. The results showed that approximately 20%-35% of the nitrogen and phosphorus nutrients were absorbed and utilized in the water environment supplemented with reclaimed water. However, the COD, turbidity, and chroma of the downstream water were significantly increased. The bacterial community of the biofilms attached to submerged macrophytes was significantly different from that in the surrounding environment (soil, sediment, and water body) and in the activated sludge that was treated by reclaimed water. In terms of bacterial community diversity, the richness and diversity were significantly lower than those of soil and sediment but higher than those of plankton bacteria in water. In terms of bacterial community composition, dominant genera and corresponding abundances were also different from those of other samples. The main dominant bacterial genera were Sphingomonas , Aeromonas , Pseudomonas, and Acinetobacter , accounting for 7%-40%, respectively. Both macrophyte species and the quality of reclaimed water (BOD 5 , TN, NH 4 + -N, and TP) could affect the bacterial community. However, the effect of water quality of the bacterial community was greater than that of macrophytes species. Additionally, the quality of reclaimed water also affected the abundance of functional genes in the bacterial community, and the relative abundance of nitrogen and phosphorus cycling functional genes was higher in areas with higher nitrogen and phosphorus concentrations.

Objective: To observe the oral acute toxicity of of (+)-usnic acid in mice and assess its cytotoxicity in rat cardiac fibroblasts., Methods: The mice with acute poisoning of (+)-usnic acid at different doses by oral administration were observed for toxic manifestations, and the LD(50) was determined. The survival time and survival rate of the mice receiving different doses of (+)-usnic acid were observed. Cultured rat cardiac fibroblasts were inoculated with different concentrations of (+)-usnic acid, and the cell growth inhibition rate was estimated and the IC(50) determined using MTT assay., Results: Higher dose of (+)-usnic acid resulted in more obvious symptoms of poisoning and shorter survival time of the mice. The LD(50) of (+)-usnic acid in mice by oral administration was 388 mg/kg. The manifestations of poisoning such as apathism, pilomotor, chill, dyspnea, torpidity and anorexia was observed. Rat cardiac fibroblasts incubated with (+)-usnic acid showed obvious growth inhibition, which was positively correlated to the dose of (+)-usnic acid, and high dose of (+)-usnic acid caused severe cell injuries. The IC(50) of (+)-usnic acid in rat cardiac fibroblasts was 322 microg/ml., Conclusion: (+)-usnic acid is a natural compound of low toxicity in mice, and low to medium dose of (+)-usnic acid dose not produce obvious cytotoxicity.

Objective: To explore the effect of usnic acid on Toxoplasma gondii tachyzoites in vitro., Methods: There are four groups named as (+)-usnic acid group, acetylspiramycin group, DMSO group and normal saline group. Groups of (+)-usnic acid and acetylspiramycin were further divided into 4 subgroups with final concentration of 5, 10, 25, 50 microg/ml respectively. Normal saline group and DMSO group were respectively given equal volume normal saline and 1% DMSO. Each group have 15 parallel tubes with 1 ml (1 x 10(6)/ml) T. gondii tachyzoites aqueous suspension. At 1 h, 2h and 4 h after drug treatment, tachyzoites were counted by light microscope with 0.4% Trypan blue staining. Tachyzoites in aqueous suspension was collected, and washed 3 times by PBS solution. Normal mice were inoculated intraperitoneally and observed for three generations. The cultivated rat cardiofibroblasts were then infected in vitro with T. gondii tachyzoites. At the same time, rat cardiomyocytes invasion by T. gondii tachyzoites was investigated., Results: At 4 h treated by 10, 25 and 50 microg/ml (+)-usnic acid, 100% T. gondii tachyzoites were stained. Some tachyzoites were swelling, blunt or round in the two ends; and granules appeared in the cytoplasm, the nuclei were deep stained. The changes of tachyzoites in acetylspiramycin group were similar to (+)-usnic acid group, 100% T. gondii tachyzoites were stained in 50 microg/ml acetylspiramycin subgroup. In inoculation tests, mice died at 8th to 9th days in 5 microg/ml (+)-usnic acid subgroup and numerous tachyzoites were detected in ascites. However, most mice survived to be killed in the other (+)-usnic acid subgroups and the tachyzoites were not found in ascites. All mice in acetylespirmycin groups died at 6th to 8th days after inoculation and many tachyzoites or pseudocysts were observed in mice ascites. In infecting cell tests, the cultivated rat cardiofibroblasts were infected in vitro by the tachyzoites after treated with 5 microg/ml (+)-usnic acid for 4 h, and pseudocysts were formed in infected cells. It was negative in the other subgroups of (+)-usnic acid. But the cultivated rat cardiofibroblasts were infected to varying degree in acetylspiramycin groups, normal saline group and DMSO group., Conclusion: (+)-Usnic acid has a remarkable effect on T. gondii tachyzoites.