Dynamic human exposure to airborne bacteria-associated antibiotic resistomes revealed by longitudinal personal monitoring data.

Airborne antibiotic-resistant bacteria (ARB) can critically impact human health. We performed resistome profiling of 283 personal airborne exposure samples from 15 participants spanning 890 days and 66 locations. We found a greater diversity and abundance of airborne bacteria community and antibiotic resistomes in spring than in winter, and temperature contributed largely to the difference. A total of 1123 bacterial genera were detected, with 16 genera dominating. Of which, 7/16 were annotated as major antibiotic resistance gene (ARG) hosts. The participants were exposed to a highly dynamic collection of ARGs, including 322 subtypes conferring resistance to 18 antibiotic classes dominated by multidrug, macrolide-lincosamide-streptogramin, ß-lactam, and fosfomycin. Unlike the overall community-level bacteria exposure, an extremely high abundance of specific ARG subtypes, including lunA and qacG, were found in some samples. Staphylococcus was the predominant genus in the bacterial community, serving as a primary bacterial host for the ARGs. The annotation of ARG-carrying contigs indicated that humans and companion animals were major reservoirs for ARG-carrying Staphylococcus. This study contextualized airborne antibiotic resistomes in the precision medicine framework through longitudinal personal monitoring, which can have broad implications for human health.

[Difference of P content in different area substrate of constructed wetland].

Adsorption of substrate is the main removal mechanisms of phosphorus in constructed wetland. It is easily impacted by various environmental factors existing in the wetland bed. The contents of substrate TP and the main inorganic P in different areas of both horizontal sub-surface flow constructed wetland with plant and one without plant were measured after treating wastewater five months. Different areas of the wetland with plant differed greatly in the substrate TP. Rhizosphere substrate in front area had the highest TP content and achieved 0.75 g x kg(-1), and the TP content of non-rhizosphere substrate in back area was only 0.21 g x kg(-1). The TP content of substrate in different areas of the wetland without plant had a little variety and ranged only between 0.21 and 0.27 g x kg(-1). Averagely, the substrate TP content in the wetland with plant was higher than the one in the wetland without plant. The phosphorous with Fe-bound (Fe-P), Al-bound (Al-P), and Ca-bound (Ca-P) were main inorganic phosphorous existing in the substrate in both wetlands, their contents in different areas substrate all increased, compared with the one before experiment. Fe-P and Al-P in different substrates in both wetlands had a similar variety. Their content between rhizosphere and intermediate substrate of front area in the wetland with plant and other area substrate in both wetlands differed greatly because the former increased greatly. Compared with Fe-P and Al-P, the variety of Ca-P in different substrates in both wetlands was low. But the content of Ca-P in rhizosphere substrate in wetland with plant was higher than other two parts respectively in front and back areas. Obviously, the plant root had an impact on the phosphorous content of substrate in constructed wetland. For TP, Fe-P, Al-P, Ca-P and loosely sorbed phosphorous in substrate, it increased with distance of the root.

[Effects of allelochemical EMA isolated from Phragmites communis on algal cell membrane lipid and ultrastructure].

In order to reveal the antialgal mechanisms of allelochemicals, effects of the allelochemical eathyl-2-methyl acetoacetate (EMA) on cell membrane lipid and ultrastructure of Chlorella pyrenoidosa, Microcystis aeruginosa and Chlorella vulagaris were studied in this paper. The lipid fatty acids of the algal membrane were isolated following the Bligh and Dye method and quantified by gas chromatograph/mass spectrometry. The ultrastructure of algal cells was observed with TEM. The results showed that EMA increased the contents of linolenic acid and linolic acid with increment of 14%, while decreased the content of myristic acid and cetylic acid in C. pyrenoidosa, membrane. The content of unsaturated fatty acids C18:1 and C18:2 increased 12% and 10% in M. aeruginosa with the addition of EMA, while the content of saturated fatty acids C18:0 and C16:0 decreased. EMA showed no significant change in the fatty acid composition in C. vulagaris under the experiment condition. EMA broke off cell wall of C. pyrenoidosa and M. aeruginosa. EMA damaged the cell membrane and the inclusion of algal cell leaked out. Nuclear and mitochondrial structure was damaged with the addition of EMA. EMA showed no significant change in the ultrastructure of C. vulgaris.

[Effects of allelochemical isolated from Phragmites communis on algal membrane permeability].

Efflux of K+, Mg2+, Ca2+ ions from algal cells as signals of cell membrane permeability, inductively coupled plasma mass spectrometry (ICP-MS) as detection method of ions, the present research investigated effects of allelochemical eathyl-2-methyl acetoacetate (EMA) isolated from Phragmites communis on cell membrane permeability of Microcystis aeruginosa, Chlorella pyrenoidosa and Chlorella vulagaris. The results showed that, when the cells were boiled for 10 min and the membrane was destroyed absolutely, the K+ efflux of M. aeruginosa and C. pyrenoidosa were 1.45 and 1.59 microg x (10(9) cell) (-1), respectively. When the concentration of EMA was 2 mg x L(-1), the K+ efflux of M. aeruginosa and C. pyrenoidosa were 1.38 and 1.40 microg x (10(9) cell)(-1), respectively. The K+ efflux of M. aeruginosa and C. pyrenoidosa reached 1.44 and 1.58 microg x (10(9) cell)(-1) while the EMA was 4 mg x L(-1). When the concentrations were 2 mg x L(-1) or 4 mg x L(-1) the K+ efflux reached more than 95% of the total ion amount in M. aeruginosa and C. pyrenoidosa cells. But when EMA concentration was 4 mg x L(-1), K+ efflux of C. vulagaris was 0.64 microg x (10(9) cell)(-1), which was only 31.5% of total K+ amount in C. vulagaris. Effects EMA on efflux of Mg2+ and Ca2+ were similar to those of K+. The results indicated that EMA destroyed the cell membrane of M. aeruginosa and C. pyrenoidosa but not C. vulagaris. This is one of the mechanisms of EMA species-selective antialgal.

[Hydrodynamic effects of the oxidation ditch on the removal efficiency and energy consumption].

The hydrodynamic characteristics in the oxidation ditch have great effects on the distributions of the dissolved oxygen and the velocity gradient, and then make important effects on the removal efficiency and energy consumption. The single-ditch Passver oxidation ditch with the capacity of 500 m3/d was investigated. The measurement and computer simulation were carried out on the velocity gradient and degrees, 180 degrees, respectively, which lied on the corner of the downriver of the aerator. The local energy consumption could be decreased by 10% after the guided wall with 180 degrees opening angle was installed. Under the condition that the velocity of the aerator was 72 r/min, the installation of the 180 degrees guided wall could not effect the distribution of DO concentration. According to the operation results of treating the municipal wastewater with low concentration, the IAWPRC model was used to simulate the water qualities in the oxidation ditch with the 180 degrees guided wall or not, respectively. The simulation results showed that the water qualities in the effluent didn't change a lot after the 180 degrees guided wall installed.

[Effect of environment and nutrient factors on the content of nitrogen and phosphorus in two duckweeds species: Spirodela polyrrhiza and Lemna aequinoctialis].

Effects of temperature, light density, nitrogen level and phosphorus level of medium to the content of two species Spirodela polyrrhiza and Lemna aequinoctialis were researched. The results showed that the content of nitrogen in two species kept constant when the concentration of nitrogen was higher than 3 mg x L(-1) and temperature higher than 25 degrees C. It decreased under lower concentrations of nitrogen and lower temperature. Photon flux density had no effect on it. But weak photon flux density and low temperature led to reduce the content of phosphorus of duckweed. The content of phosphorus in two duckweed species kept constant when photon flux density was higher than 8 000 1x and temperature higher than 25 degrees C. The relationship between the content of phosphorus and concentrations of phosphorus in medium could be described by Monod model. The saturated phosphorus content of Spirodela polyrrhiza was higher than Lemna aequinoctialis.

[Growth feature of biomass of Lemna aequinoctialis and Spirodela polyrrhiza in medium with nutrient character of wastewater].

Duckweeds have an important potential in nutrient recovery from wastewater because of their rapid multiplication and high protein content in biomass. The growth rate of duckweed biomass has a direct relationship with nutrient removal and recovery. With laboratory experiments of batch culture and continuous culture, the growth curves of two duckweed species, Lemna aequinoctialis and Spirodela polyrrhiza, cultivated in different media were gotten and fitted by Logistic model. The effect of nitrogen on growth of duckweed was evaluated. Experimental results indicated that the growth curve had characteristic of sigmoidal shape and the growth rate had density-dependent characteristic. Results of statistical analysis demonstrated that Logistic model is suitable to describe the growth of single duckweed specie. The maximal growth rate from regression in medium with ammonia nitrogen was lower than those in medium with nitrate nitrogen. The maximal growth rate of Lemna aequinoctialis was higher than Spirodela polyrrhiza The paper also discussed the application of Logistic model in harvesting of duckweed biomass from wastewater.