To study the effects of long-term mining activities on the agricultural soil quality of Mengnuo town in Yunnan province, China, the heavy metal and soil enzyme activities of soil samples from 47 sites were examined. The results showed that long-term mining processes led to point source heavy metal pollution and Pb, Cd, Zn and As were the primary metal pollutants. Polyphenoloxidase was found the most sensitive soil enzyme activity and significantly correlated with almost all the metals (P < 0.05). Amylase (for C cycling), acid phosphatase (for P cycling) and catalase (for redox reaction) activities showed significantly positive correlations (P < 0.05) with Pb, Cd, Zn and As contents. The correlations between soil enzymes activities and Cd, Pb and Zn contents were verified in microcosm experiments, it was found that catalase activity had significant correlations (P < 0.05) with these three metals in short-term experiments using different soils under different conditions. Based on both field investigation and microcosm simulation analysis, oxidoreductases activities (rather than a specific enzyme activity) were suggested to be used as "core enzyme", which could simply and universally indicate the heavy metal pollution degrees of different environments. And hydrolases (for C, N, P and S recycling) could be used as a supplement to improve correlation accuracy for heavy metal indication in various polluted environments.

This study focused on a haloduric BTEX-degrading microbial consortium EC20 enriched from Bohai Sea sediment. EC20 degraded 87% of BTEX at 435 mg L initial concentration (benzene, toluene, ethylbenzene, and xylenes in equal proportions) in the presence of 3.4% NaCl. 16S rRNA gene-based PCR-DGGE profiles revealed that the dominant bacteria in EC20 were Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes at the phylum level, and Pseudomonas, Mesorhizobium, Achromobacter, Stenotrophomonas, and Halomonas at the genus level. PCR detection of genes coding the key enzymes which participated in BTEX degradation pathways showed that the enriched consortium EC20 contained TOL pathway and TOD pathway to initiate biodegradation of BTEX.

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Petroleum exploitation causes serious pollution to the semi-enclosed Bohai Sea (China) ecosystem. However, little is known about the influence of such pollution on the αand β-diversity of the bacterial communities or the in situ hydrocarbon biodegradation potential present in the surface sediments. This was explored using 16S rRNA gene-based terminal restriction fragment length polymorphism, along with alkane hydroxylase (AlkB) and soluble di-iron monooxygenase (SDIMO) gene-based clone libraries. α-diversity (Shannon-Weaver index) was negatively correlated with the BTEX (i.e. benzene, toluene, ethylbenzene, and xylene) and total nitrogen contents. β-diversity at the phylum/class level (class level for Proteobacteria) and terminal restriction fragment (T-RF) level responded differently to the abiotic factors. At a small to intermediate scale (21.4 to 142.2 km), β-diversity at the T-RF level was closely correlated with geographic distances, while at the phylum/class level, it was significantly influenced by environment heterogeneity. In total, 72.61% of the AlkB sequences were related to Gammaproteobacteria, including Alcanivorax and Marinobacter, while the SDIMO genes were similar to Phenol-2, Mmo, ThmA, PmoC and PrmA genes, with 72% of the sequences found being novel. The high SDIMO gene diversity might be related to the complexity of the hydrocarbon pollution (a mixture of phenol, methane, tetrahydrofuran, propene and propane) and demonstrates the existence of in situ hydrocarbon biodegradation potential. Information about the diversity of bacteria and the hydroxylases is helpful to guide the in situ bioremediation of petroleum pollution and protect ecosystem function in the Bohai Sea.