Cheng Ding

The Impact of Spartina alterniflora on the Soil Microbial Assemblages in Jiangsu Coast

The soil microbial assemblages in coastal region is strongly influenced by a wide variety of factors, such as vegetation types and tides. In order to examine the influence of Spartina alterniflora, an exotic species, on the soil microbial assemblages, comparative pairs of experiments were conducted of soil from S. alterniflora marshes and Suaeda salsa marshes for collecting data on soil characteristics, quantity of bacteria, fungi, actinomycetes and azotobacters per gram of dried soil and denaturing gradient gel electrophoresis (DGGE) band profiles. The results revealed that S. alterniflora depressed not only the quantity of microorganisms but also the richness of bacterial community. And, it might suggest that the microbial assemblages were more influenced by vegetation types than tides. Thus, we proposed that the introduction of S. alterniflora into Chinese coastal region should be forbidden.

Soil Microbial Community Response to Nitrobenzene Exposure for a Spartina Wetland

To explore the response of the soil microbial community to nitrobenzene (NB) exposure in a Spartina marsh, a short-term (45 d) mesocosm study was conducted at three NB concentrations of (10, 50, and 100) mg kg−1. Dry soil, sterile and unsterile controls were also compared. The ability of the microbes to biodegrade NB was studied in an effort to predict the outcome of NB in the mesocosm. The results indicated that a microbial community is capable of doing so. Microbial enumeration and enzyme assays showed that the fluctuations in microbial communities and polyphenol oxidase activities are related to the initial NB concentration. Moreover, cluster analyses through denaturing gradient gel electrophoresis (DGGE) revealed very similar patterns (95.5%) throughout the 45 d term, indicating that the microbial community regenerates when NB is exhausted. Although volatilization and photolysis were the major processes responsible for the reduction in NB in contaminated mesocosms and the microbial community regenerated at the end of incubation, the data indicate potential ecological risks in outfall areas even if the discharged wastewater complies with the national wastewater discharge standards.

The Response of Antioxidant Enzyme and ATPase in Bacteria Exposed to 1,2-dichlorobenzene

The activity response of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), ATP enzyme activities of Escherichia coli Q8, Bacillus subtilis L11, and Bacillus cereus OL-1 following exposure to 1,2-dichlorobenzene (1,2-DCB) was investigated. The bacterial strains were treated with the different concentrations of 1,2-DCB. Results obtained indicated that SOD and CAT activities in the tested bacteria increased significantly in a concentration-dependent manner after different concentrations of 1,2-DCB were applied. The activity of SOD in B. subtilis was stimulated and reached the highest level after treatment with 10 mg/L 1,2-DCB for 3 h. For B.cereus OL-1, there was another stimulation of SOD activity after 1,2-DCB application for about 5 h The stimulation by 1,2-DCB showed a relative lag for E. coli. 1,2-DCB had an evident influence on ATPase activity in the three bacteria within a relatively short period. 1,2-DCB would have caused a certain oxidative stress on the three bacteria which may not only elevate SOD and CAT activities but also generate new SOD isozymes to antagonize oxidative stress. All indirectly reflect the existence of poisonous and harmful material in the environment , and can indicate the influence of pollution sensitivily. Therefore SOD, CAT and ATP enzyme activity in microbial body can be regarded as a molecular index of polluting ,which is feasible.

Spatial distribution of total halogenated organic compounds (TX), adsorbable organic halogens (AOX), and heavy metals in wetland soil irrigated with pulp and paper wastewater

Abstract Long-term irrigation using wastewater from paper industry may cause seriously problems to the receiving soil. This work surveyed and monitored the soil quality of a wastewater irrigation wetland system in Yancheng City, Jiangsu Province in China in 2014 and 2015. Τhe wetland soil showed different soil properties and TX, AOX, heavy metal contents after long-term wastewater irrigation. Long-term irrigation also accumulated the heavy metals such as Cu, Cd, Zn, and Pb in the wetland soil. Compared to the control, TX in the irrigated soil increased by 47.7–69.8% (2014) and 61.5–83.1% (2015). AOX varied in concentration from 1.7 to 55.0 mg kg−1 (2014) and 11.0 to 53.0 mg kg−1 (2015). The long-term irrigation of wastewater to wetland systems caused the accumulations of heavy metals, TX, and AOX in the soil and the levels of accumulations were related to several factors including soil properties, wastewater quality, and irrigation time.

Effects of bleaching wastewater irrigation on soil quality of constructed reed wetlands

Abstract Constructed reed wetland microcosms (CRWs) in a lab of east China have been irrigated with bleaching wastewater per month for a reed growth season. The soil physicochemical properties, enzyme activities (i.e. urease, invertase, polyphenol oxidase, alkaline phosphatase and cellulase) and soil microbial diversity were assayed before and after the exposure experiment. Compared to the river water irrigated controls (CKs), bleaching wastewater application has no marked influence on soil pH, but significantly increased soil Na+, total halogen and absorbable organic halogen (AOX) contents, which induced the increasing of soil electrical conductivity. Furthermore, soil enzyme activities displayed significant variation (except for polyphenol oxidase). Bleaching wastewater irrigation decreased Sorenson’s pairwise similarity coefficient (Cs), which indicated the changes of the structure of bacterial and fungal communities. However, only the diversity of bacterial community was inhibited and has no effect on the diversity of fungal community, as evidenced by the calculated Shannon–Wiener index (H).

Influence of 1,2-Dichlorobenzene on Anaerobic Microorganisms in Wetland Soil

The potential effect of 1,2-dichlorobenzene (1,2-DCB) on anaerobic microbial populations was investigated in a flooded wetland soil. Numbers of anaerobic fermentative bacteria (AFB), denitrifying bacteria (DNB) and hydrogen-producing acetogenic bacteria (HPAB) were numerated by three-tube anaerobic most-probable-number (MPN) methods with anaerobic liquid enrichment media. In anaerobic microbe groups, the changes of bacterium group were not the same. 1,2-Dichlorobenzene had the maximum influence on microbial groups of wetland soil at the initial pollution. In dealing with 14-35 days, bacterium groups in each processing soil have different amplitude bouncing back. In the experimental process, bacteria which produces hydrogen and acetic acid is most sensitive to 1,2-Dichlorobenzene. Hydrolysis fermentation bacteria second, and denitrifying bacteria was the smallest.

Isolation of Dye Decolorization Bacteria and the Study on the Conditions of Dyes Decolorization

A bacterium which had the ability of decoloration on Malachite Green was isolated from Zhenjiang printworks and was identified as Pseudomonas aeruginosa. The effects of concentration of the dye concentration、cultural time、cultural temperature and initial pH of cultural medium on the efficiency of decoloration were investigated. The result shows that the optimal cultural conditions was: dye concentration was 50mg∙l-1，cultural time was 72h，cultural temperature was 28℃，initial pH of cultural medium was 7.0.

Isolation, Identification and Degradation Characterization of 1,2-Dichlorobenzene Degrading Strain

A bacterium(strain DL-1) capable of growing with1,2-dichlorobenzene as sole carbon and energy sources was isolated from rhizosphere soil in phragmites wetland by using the enrichment culture contaminated with1,2-dichlorobenzene concentration gradient of 20, 40, 60，80, 120, 160 and 200 mg•L-1. It was identified as Bacillus cereus by 16S rDNA gene sequence analysis and the bacterial culture characteristics, carried physiological and biochemical research, the strain was Gram-positive, peritrichous flagellum。 The further degrading characterization reserch proved the strain was a facultative anaerobe and the optimal temperature, pH value and inoculation amount of 1,2-dichlorobenzene degradation were 30℃, pH7.0 and 10%, in 4 d. Respectively , the optimal concentration of 1,2-dichlorobenzene in four days was 120 mg•L-1.