[Response of Soil Respiration and Organic Carbon to Returning of Different Agricultural Straws and Its Mechanism].

Soybean, maize and rice straws were selected as raw materials to study the response of the soil respiration (SR) and soil organic carbon (SOC) to returning of different straws in the Chongming Dongtan area. The results showed that all of SR, SOC and the plant biomass of the lands with returning of different straws were higher than those of the controls. The soil with soybean straw returning possessed the lowest SR and highest SOC among the three kinds of straws, meaning its higher soil organic carbon sequestration capability than corn and maize straws returning. Straw returning significantly enhanced soil dehydrogenase, ß-glycosidase activities and microbial biomass, and soil dehydrogenase activity was significantly correlated with soil respiration. The dehydrogenase activity of the soil with soybean straw returning was the lowest, thus, the lowest SR and highest SOC. Soybean straw had the highest cellulose and lignin contents and the lowest N content among the three kinds of straws, resulting in its lowest biodegradability. Therefore, when soybean straw was returned to soil, it was difficult to degrade completely by soil microorganisms, thus the lowest soil microbial activity, eventually leading to the lowest SR and highest SOC.

[Response of Straw and Straw Biochar Returning to Soil Carbon Budget and Its Mechanism].

Direct straw returning and straw carbonization returning are the main measures of straw returning. Because of the differences in structure and nature as well as returning process between straw and straw biochar, the soil respiration and soil carbon budget after returning must have significant differences. In this study, outdoor pot experiment was carried out to study the response of soil respiration and carbon budget to straw and straw biochar returning and its possible mechanism. The results showed that soil respiration of straw biochar returning [mean value 21. 69 µmol.(m2.s)-1] was significantly lower than that of direct straw returning [mean value 65.32 µmol.(m2.s)-1], and its soil organic carbon content ( mean value 20. 40 g . kg-1) and plant biomass (mean value 138. 56 g) were higher than those of direct straw returning (mean values 17. 76 g . kg-1 and 76. 76 g). Considering the carbon loss after the biochar preparation process, its soil carbon budget was also significantly higher than that of direct straw returning, so it was a low carbon mode of straw returning. Direct straw returning significantly promoted soil dehydrogenase activity, soil ß-glycosidase activity and soil microorganism quantity, leading to higher soil respiration, but straw biochar did play an obvious role in promoting the microbial activity index. Easily oxidizable carbon (EOC) and biodegradability of straw biochar were lower than those of straw, which showed that straw biochar had higher stability, and was more difficult to degrade for soil microorganisms so its soil microbial activity was generally lower, and could be retained in the soil for a long time.

Enhanced CO2 fixation by a non-photosynthetic microbial community under anaerobic conditions: optimization of electron donors.

To enhance the CO(2) fixation efficiency of the non-photosynthetic microbial community (NPMC) isolated from sea water under anaerobic conditions without hydrogen, the concentration of inorganic compounds as electron donors and their ratios were optimized by response surface methodology design (RSMD). The results indicated that the CO(2) fixation efficiency of NPMC using NaNO(2), Na(2)S(2)O(3) and Na(2)S as the electron donors was increased about 90%, 75% and 207%, respectively. Additionally, there were interactions between two electron donors and three electron donors. Central composite RSMD experimentation predicted that the optimal concentration and ratios of these inorganic compounds was 1.04% NaNO(2), 1.07% Na(2)S(2)O(3) and 0.98% Na(2)S. Under these conditions, the fixed CO(2) was 139.89 mg/L, which obviously exceeded the amount prior to optimization, as well as when H(2) was used as an electron donor. The established electron donor system can effectively enhance the CO(2) fixation efficiency of NPMC without hydrogen under anaerobic conditions.

Optimization of electron donors to improve CO2 fixation efficiency by a non-photosynthetic microbial community under aerobic condition using statistical experimental design.

To improve the CO(2) fixation efficiency of non-photosynthetic microbial community (NPMC) isolated from sea water under aerobic conditions without hydrogen, the concentration of inorganic compounds as electron donors and their ratios were optimized using response surface methodology design (RSMD). These results indicated that Na(2)S, followed by Na(2)S(2)O(3) and NaNO(2) enhanced the CO(2) fixation by NPMC and the efficiency was increased about 100%, 200% and 200%, respectively. Some interaction between NaNO(2) and Na(2)S(2)O(3), as well as between Na(2)S(2)O(3) and Na(2)S was observed. Central composite RSMD experimentation predicted that the optimal concentration of these inorganic compounds and their ratios was 0.457% NaNO(2), 0.50% Na(2)S(2)O(3) and 1.25% Na(2)S. Under these conditions, the fixed CO(2) was 105.76 mg/L, which obviously exceeded the amount before optimization, as well as that obtained using hydrogen as the electron donor. This indicates that the NPMC using the established electron donors system can effectively fix CO(2) without light and hydrogen gas under aerobic condition.

[Establishment of microarray for detecting mutation in HBV pre-core/core and basic core promoter regions].

OBJECTIVE: To develop a sensitive and specific microarray for detecting mutations of HBV pre-core/core and basic core promoter regions in the clinic. METHODS: Site-specific oligonucleotide probes were designed and immobilized to microarray slides and hybridized to HBV gene fragments amplified with specific biotin-labeled primer using asymmetrical PCR. The specificity and sensitivity of the method were estimated. And the microarray was applied to detect 138 clinical serum samples with HBV-DNA. RESULTS: The mutations of HBV pre-core/core and basic core promoter regions can be specifically detected using the microarray, and the sensitivity was 1 x 10(1) copies/microl. Among 138 samples, 40 samples had T1762/ A1764 mutation, 11 samples had C1814 mutation, and 16 samples had A1896 mutation. The A1896 mutation rate in high HBV-DNA load group was significantly higher than that in low HBV-DNA load group (P < 0.01). CONCLUSION: An DNA microarray assay was successfully established to detect the mutations in HBV pre-core/core and basic core promoter regions. The A1896 mutation in pre-core/core region maybe involve in duplication of HBV.

[Difference and its formation cause in soil organic carbon accumulation capability of two typical tidal wetlands at Dongtan of Chongming Island in Shanghai].

Through the analyses of soil organic carbon content and vegetation input, this paper studied the difference in soil organic carbon accumulation capability of two typical tidal wetlands, one (A) was on the erosion bank with Phragmites communis and sandy loam soil at southeast Dongtan in Shanghai, and the other (B) was on the alluvial bank with P. communis, Spartina alterniflora, and clay soil at northeast Dongtan of Chongming Island. The main formation causes of the difference were analyzed based on the determinations of soil microbial activities and physical-chemical properties. In A, the average soil total organic carbon content was 46.10% (P < 0.05) of that in B, while the annual aboveground vegetation dry mass was only 9.16% lower than that in B, illustrating that the soil organic carbon output was higher in A than in B. The total count of soil bacteria and the activities of soil catalase and invertase in A were 3.82 times (P < 0.05), 46.81% (P < 0.05), and 34.33% (P < 0.05) higher than those in B, respectively, and the soil microbial respiration in A was also higher than that in B, which indicated that the stronger soil microbial C-metabolic activity in A was the main cause inducing the lower soil organic carbon accumulation capability. The sandy loam soil in A had higher porosity and lower salinity and moisture, being favorable to the growth of soil microbes and the decomposition of soil organic carbon, while the clay soil in B had higher salinity and moisture but lower microbial activity, leading to the weaker soil organic carbon decomposition and higher organic carbon accumulation.

[Breeding, optimization and community structure analysis of non-photosynthetic CO2 assimilation microbial flora].

Isolation and screening from sea water and sediments, and the optimization of electron donor and inorganic carbon source structure were performed for obtaining microbial flora with high efficient inorganic carbon fixation without the light and hydrogen. In addition, the structure of the microbial flora was studied through 16S rDNA sequence analysis and contrast for providing theoretical basis to improve carbon fixation efficiency through optimizing microbial flora structure. The result showed that non-photosynthetic microbial flora with the capacity of inorganic carbon fixation under the general aerobic and anaerobic conditions could be obtained from the sea by long-term domestication and isolation. Inorganic carbon fixation efficiency of the microbial flora was enhanced significantly by adding of sodium thiosulfate, sodium sulfide and hydrogen as electron donor. Under the aerobic and anaerobic conditions with sodium thiosulfate as electron donor, the efficiency of inorganic carbon assimilation was 10.44 mg/L and 12.56 mg/L respectively. The assimilation efficiency of the microbial flora with mixed inorganic carbon source was higher than that with single carbon source. When CO2, sodium bicarbonate and sodium carbonate were added as carbon sources, carbon fixation efficiency of the microbial flora under the aerobic and anaerobic condition was 110 mg x (L x d)(-1) and 72 mg x (L x d)(-1) respectively which had been closed to the efficiency of hydrogen-oxidizing bacteria. The analysis results showed that the predominant species of the microbial flora varied significantly after the adding of different electron donor. And 11 species of the 16 predominant species in the microbial flora was uncultured. It means that the microbial flora could only exist in symbiotic manner. The inorganic carbon fixation effect of the microbial flora may be the results of co-function of multi-microbial species. Therefore, the optimization of microbial flora structure and proportion is benefit for the further improvement of carbon fixation efficiency.

Evaluation of the effectiveness and safety of the thermo-treatment process to dispose of recombinant DNA waste from biological research laboratories.

The discharge of recombinant DNA waste from biological laboratories into the eco-system may be one of the pathways resulting in horizontal gene transfer or "gene pollution". Heating at 100 degrees C for 5-10 min is a common method for treating recombinant DNA waste in biological research laboratories in China. In this study, we evaluated the effectiveness and the safety of the thermo-treatment method in the disposal of recombinant DNA waste. Quantitative PCR, plasmid transformation and electrophoresis technology were used to evaluate the decay/denaturation efficiency during the thermo-treatment process of recombinant plasmid, pET-28b. Results showed that prolonging thermo-treatment time could improve decay efficiency of the plasmid, and its decay half-life was 2.7-4.0 min during the thermo-treatment at 100 degrees C. However, after 30 min of thermo-treatment some transforming activity remained. Higher ionic strength could protect recombinant plasmid from decay during the treatment process. These results indicate that thermo-treatment at 100 degrees C cannot decay and inactivate pET-28b completely. In addition, preliminary results showed that thermo-treated recombinant plasmids were not degraded completely in a short period when they were discharged into an aquatic environment. This implies that when thermo-treated recombinant DNAs are discharged into the eco-system, they may have enough time to re-nature and transform, thus resulting in gene diffusion.

Determination of cobalt at ng ml(-1) level in water using the electrophilic substiution complexation between co(II) and chlorophosphonazo-p-CL-Cu(II) complex.

The chromophore chlorophosphonazo-p-Cl (PCCPA) was used to complex Co(II) and Cu(II) at pH 9.18. The formation of Co(PCCPA)2 and Cu(PCCPA)2 complexes were characterized by the spectral correction technique. Co(II) could competitively substitute Cu(II) from the Cu(II)-PCCPA complex via electrophilic effect. With the assistance of the light-absorption ratio variation approach, the electrophilic substitution complexation showed a high selectivity and good sensitivity with 1.9 ng mL(-1) of LOD. The proposed method has been applied to the direct detection of Co(II) in surface water and wastewater with good percent of recovery.