Evaluation of genotoxic effects caused by extracts of chlorinated drinking water using a combination of three different bioassays.

Potential genotoxic effects of chlorinated drinking water now are of a great concern. In this study, raw water, finished water, and tap water from a water plant in Wuhan, China were collected in two different sampling times of the year (January and July). Genotoxic effects of water extracts were evaluated using a combination of three different bioassays: SOS/umu test, HGPRT gene mutation assay, and micronucleus assay, which were separately used to detect DNA damage, gene mutation, and chromosome aberration. The results of three different bioassays showed that all water samples in January and July induced at least one types of genotoxic effects, of which the DNA-damage effects were all detectable. The levels of DNA-damage effects and gene-mutation effects of finished water and tap water in January were higher than those in July. Chlorination could increase the DNA-damage effects of drinking water in January and the gene-mutation effects of drinking water in both January and July, but did not increase the chromosome-aberration effects of drinking water in both January and July. Our results highlighted the importance of using a combination of different bioassays to evaluate the genotoxicity of water samples in different seasons.

Response of primary vectors and related diseases to impoundment by the Three Gorges Dam.

OBJECTIVES: To investigate the impact of the Three Gorges Dam on the local ecological environment. We conducted a 3-year cross-sectional survey of natural focus infectious diseases in the area before and after the water level rose to 156 m to evaluate the dam's health impacts. METHODS: Direct and indirect immunofluorescence methods were applied to detect rat antigen and antibody of haemorrhagic fever with renal syndrome (HFRS). Fresh rat kidneys were inoculated in Korth's culture medium to detect Leptospira. A group of captured crabs were ground to observe the metacercariae of Paragonimus. Serum samples were collected from healthy local individuals. ELISA kits were used to detect human antibody against HFRS and paragonimiasis. Human Leptospira infections were detected by a microscopic agglutination test. RESULTS: Upstream rodent density increased significantly with Rattus flavipectus and Apodemus agrarius as the major pathophoric genera. The infection rate of human HFRS and Leptospira in the upstream human population samples was significantly higher than in the downstream samples and correlated with the increase in rodent density. Paragonimus infection rates remained at a low level during the study. Culex pipiens fatigan and Armigeres obturbans were the dominant species of mosquito. CONCLUSIONS: The creation of the Three Gorges Dam changed the proliferation of intermediary agents of diseases, but not notably. However, the ecological effects on the environment may require a prolonged period of time to manifest themselves; thus, long-term and effective surveillance of vectors and related diseases needs to be established.

Spatial and temporal evaluations of estrogenic activity in tap water served by a water plant in Wuhan, China.

This study aimed to evaluate the spatial and temporal characteristics of estrogenic activities in tap water served by a water plant in Wuhan, China. Tap water samples were monthly collected from the three sampling sites with different distances of distribution network from the plant during April 2010-March 2011: Min (less than 0.1km), Mid (approximately 4km) and Max (approximately 8km). Estrogenic activities of solid phase-extracted tap waters were measured by using recombinant yeast assay incorporated with and without exogenous metabolic activation system (rat liver S9 fractions) and expressed as 17ß-estradiol equivalents (EEQ). Pro-estrogenic and estrogenic activity in tap water ranged from 151.4 to 1395.6pg EEQ/L and 35.2 to 1511pg EEQ/L, respectively. Average pro-estrogenic activity (680.3pg EEQ/L) was significantly higher than estrogenic activity (412.8pg EEQ/L) throughout the whole year. The pro-estrogenic activity significantly increased with the extending of distribution network, and was also statistically correlated with water temperature and pH. However, pro-estrogenic and estrogenic activity was not altered across four seasons. Our results suggest that the pro-estrogenic and estrogenic chemicals are present in tap water served by the water plant.

Optimization of Douchi fibrinolytic enzyme production by statistical experimental methods.

Thrombus disease, one of the common cardiovascular diseases, has attracted worldwide attention for its rising mortality and morbidity. Due to the distinct shortages of current fibrinolytic drugs, new fibrinolytic agents warrant investigation. In this study, 8 fibrinolytic enzyme-producing strains were isolated from Douchi-a traditional Chinese food, and strain XY-1 which produced the largest amount of the enzyme was chosen for the following experiments. The enzyme produced by strain XY-1 was named Douchi fibrinolytic enzyme (DFE). We optimized the liquid culture medium of strain XY-1 for enzyme production using Plackett-Burman and Box-Behnken design. The predicted maximal DFE yield was 19.78 FU/mL with 11.4 g/L peptone, 0.5 g/L magnesium sulfate and 1 g/L sodium chloride. However, we acquired maximal production of 21.33 FU/mL in actual experiments, equal to 107.84% of the theoretical value, and the yield had been increased by 79.55% as compared to the yield of un-optimized culture. It was demonstrated that the combined use of Plackett-Burman design and response surface methodology in fermentation optimization can effectively and rapidly increase DFE production.

Removal of nitrogen, phosphorus, and organic pollutants from water using seeding type immobilized microorganisms.

OBJECTIVE: To study the possibility of removing nitrogen, phosphorus, and organic pollutants using seeding type immobilized microorganisms. METHODS: Lakes P and M in Wuhan were chosen as the objects to study the removal of nitrogen, phosphorus, and organic pollutants with the seeding type immobilized microorganisms. Correlations between the quantity of heterotrophic bacteria and the total nitrogen (TN), total phosphorus (TP), and total organic carbon (TOC) in the two lakes were studied. The dominant bacteria were detected, inoculated to the sludge and acclimated by increasing nitrogen, phosphorus and decreasing carbon source in an intermittent, time-controlled and fixed-quantity way. The bacteria were then used to prepare the seeding type immobilized microorganisms, selecting diatomite as the adsorbent carrier. The ability and influence factors of removing nitrogen, phosphorus, and organic pollutant from water samples by the seeding type immobilized microorganisms were studied. RESULTS: The coefficients of the heterotrophic bacterial quantity correlated with TOC, TP, and TN were 0.9143, 0.8229, 0.7954 in Lake P and 0.9168, 0.7187, 0.6022 in Lake M. Ten strains of dominant heterotrophic bacteria belonging to Pseudomonas, Coccus, Aeromonas, Bacillus, and Enterobateriaceae, separately, were isolated. The appropriate conditions for the seeding type immobilized microorgansims in purifying the water sample were exposure time=24 h, pH=7.0-8.0, and quantity of the immobilized microorganisms=0.75-1 g/50 mL. The removal rates of TOC, TP, and TN under the above conditions were 80.2%, 81.6%, and 86.8%, respectively. CONCLUSION: The amount of heterotrophic bacteria in the two lakes was correlated with TOC, TP, and TN. These bacteria could be acclimatized and prepared for the immobilized microorganisms which could effectively remove nitrogen, phosphorus, and mixed organic pollutants in the water sample.

[A correlative study on heterotrophic bacteria and the main pollutant in city lakes' water].

OBJECTIVE: To provide scientific basis for bioremediation of city lake, the distribution of heterotrophic bacteria and its correlation with major pollutions condition were studied. METHODS: Puping Lake and Moshui Lake of Wu Han City were choosen as the objects of our study. COD(cr) TOC, TP and TN were determined in sampled freshwater and sediment via the standard methods. At the same time the bacteria was cultivated. RESULTS: The average value of COD(cr), TOC, TP and TN were 8. 934 mg/L, 5.125 mg/L, 0.089 mg/L, 4.739 mg/L in Puping Lake and 86.296 mg/L,13.255 mg/ L, 1.796 mg/L, 7.325 mg/L in Moshui Lake. Ten strains of heterotrophic bacteria were isolated from the sample and they are Pseudomonas, Bacillus, Enterobateriaceae, Aeromonas and Coccus. The dominant strain in water was Pseudomonas. The proportion of Bacillus in sediment was relatively higher. In the two lakes, the average bacteria counts were 1.90 x 10(3) CFU and 5.53 x 10(4) CFU per mL in water, 3.12 x 10(5) CFU and 5.06 x 10(5) CFU per g in sediment. CONCLUSION: Puping Lake and Moshui Lake were polluted seriously according to the standard; Gram negative rods were the main types in water, and the dominant type was Pseudomonas, the Gram positive bacteria was Bacillus; The type and quantity of bacteria in Moshui Lake were higher than those in Puping Lake, and there were correlations between the quantity of bacteria and the pollutants.