| More and more attention has been attracted to the Antarctic environmental contamination caused by human activities, as the study about Antarctica developed. Aiming for a better understanding about the sewage and oil contamination, we collected soil samples from suspected sites in both 2005 and 2006, and studied the microbial diversity, community structure and their changes between two years. Moreover, based on quantitative PCR method, we established an approach to assessing the concentration of xylE gene in soils. The study can be a reference for Antarctic scientific research, especially in estimating environment, planning for scientific activities and participating international cooperation about Antarctica investigation.Denaturing gradient gel electrophoresis (DGGE) was used to assess the impact of bacterial community of sewage contaminated soil in Zhongshan Station (Antarctica). The investigation was conducted on the soil samples which were collected respectively from sewage contaminated and uncontaminated areas in 2005. Both the DGGE profiles and bands sequencing showed that there are significant differences between the two samples, although they are quite similar in community structure. In the aspect of amount of microorganism, uncontaminated surface soil (0-10cm) was much more than subsurface one (10-20cm), whereas sewage contaminated soil show little difference in depth. In addition, the enrichment of Chlorella sp. and existence of some infective pathogen in sewage contaminated soil also provide some clues to assess the influence cause by sewage.Beside PCR-DGGE, microbial 16S rDNA libraries of sewage contaminated soils (collected in 2005 and 2006) were constructed and studied by PCR-RFLP (Restriction Fragment Length Polymorphism) and phylogenetic analysis based on 16S rDNA sequences. The microbial diversity and community structure in these two sites, after comparison with uncontaminated soil sample (collected from a close but sewage-proof site in 2006), revealed that two sewage contaminated site contained much more abundant 16S DNA phylotypes. Another comparison indicated that subsurface soil (10-20cm) collected in 2006 provided over two times phylotypes than 2005 subsurface soil (10-20cm) of sewage site. In addition, an enrichment of several phylotypies belonged to Enterobacteriaceae was observed in two sewage contaminated site (both surface and subsurface layer). The existence of some non-indigenous but organic matter reducing bacteria also showed the clear impacts caused by sewage water.The primary focus of the other study was on investigating the soils from Zhongshan Station (Antarctica) and detecting the area of petroleum contamination. DNA was extracted from ten soil samples from assumed contaminated sites and PCR was used for screening the presence and frequency of the catabolic genes responsible for toluene and xylene (xylE), C6-C12 n-alkines (alkB) and naphthalene (ndoB) biodegradation. The detection of alkB in subsurface soil (10-20cm) of incinerator b and xylE in both upper (0-10cm) and lower layer (10-20cm) of incinerator a and b showed that incinerators may be seriously contaminated sites for garbage burning. Only xylE can be detected as far as 10m from the incinerator b in both upper and lower layer. PCR-RFLP analysis with Afa I and Msp I indicated that a majority of clones possessed the same restriction pattern as Pseudomonas sp. ST41 and Pseudomonas stutzeri. The result indicates that (i) xylE detection is more sensitive than alkB in evaluating the soil after the petroleum-contamination events; (ii) the soil of incinerator a and b were severely contaminated and the range of contamination is supposed beyond the area of a radius of 10m of the incinerator b and 20cm at least in depth. At last, the result of quantitative PCR showed that an average of 106 copies/g soil was detected in two incinerators.
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