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We studied the dechlorination process of Aroclor1260, a high-chlorinated polychlorinated biphenyls (PCBs) mixture in an anaerobic paddy soil slurry, and further analyzed the related microbial community structures. The Aroclor1260 was reduced up to 55.5% in the natural paddy soil slurry in 128 days, and the reduction percentage dropped to 46.9% after incoculating the paddy soil slurry with a PCBs-dechlorination enrichment culture. The dechlorination mainly occurred in congeners of pentachlorobiphenyl, hexachlorobiphenyl, and specially, the heptachlorobiphenyl, with pentachlorobiphenyl accumulated as dechlorination intermediate. Hydrogen gas produced from fermentation of organic matters was maintained at a lower partial pressure due to its consumption during the dechlorination process, so that the methanogens was suppressed as well. The microbial community structure was significantly different between natural and inoculated paddy soils. Introducing the PCBs-dechlorination enrichment culture changed the local microbial community by the competition between the exogenetic dchlorinators and the indigenous bacteria, overall decreasing the dechlorination activity.

Biphenyl (BP)-degrading bacteria were identified to degrade various polychlorinated BP (PCB) congers in long-term PCB-contaminated sites. Exploring BP-degrading capability of potentially useful bacteria was performed for enhancing PCB bioremediation. In the present study, the bacterial composition of the PCB-contaminated sediment sample was first investigated. Then extracellular organic matter (EOM) from Micrococcus luteus was used to enhance BP biodegradation. The effect of the EOM on the composition of bacterial community was investigated by combining with culture-dependent and culture-independent methods. The obtained results indicate that Proteobacteria and Actinobacteria were predominant community in the PCB-contaminated sediment. EOM from M. luteus could stimulate the activity of some potentially difficult-to-culture BP degraders, which contribute to significant enhancement of BP biodegradation. The potentially difficult-to-culture bacteria in response to EOM addition were mainly Rhodococcus and Pseudomonas belonging to Gammaproteobacteria and Actinobacteria respectively. This study provides new insights into exploration of functional difficult-to-culture bacteria with EOM addition and points out broader BP/PCB degrading, which could be employed for enhancing PCB-bioremediation processes., (© 2015 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.)

Polychlorinated biphenyls (PCBs) are the typical persistent organic pollutants (POPs) in the environment. As a ubiquitous attenuation course of chlorinated organic compounds in anoxic environment, the microorganism-mediated reductive dechlorination process plays an important role in PCBs transformation, especially the transformation of higher chlorinated PCBs. The higher chlorinated PCBs can be dechlorinated in anaerobic condition, and thus, their persistence and toxicity can be decreased. The resultant lower chlorinated PCBs from the dechlorination can be further degraded and completely mineralized in aerobic condition. This paper summarized the research advances of PCBs microbial reductive dechlorination, introduced the mechanisms and characteristics of the dechlorination and the related specific microorganisms, and approached the affecting factors of PCBs bio-dechlorination, as well as the significances of anaerobic dechlorination coupling with aerobic degradation. The future research directions, including the complex metabolic networks of dechlorinating microbial populations, the screening of novel specific dechlorinators and their practical applications in the remediation of PCBs contaminated sites were also prospected.

Persistent organic pollutants have increasingly become a critical environmental concern, while thermophiles have the high potential of degrading various kinds of environmental organic pollutants. At high temperatures, thermophiles have higher metabolic activity, and the competition by mesophiles is reduced, meanwhile, the solubility and bioavailability of some persistent organic pollutants are greatly increased, and thus, the degradation of the pollutants by thermophiles is more rapid and complete. Therefore, thermophils are of great significance for the bio-treatment of organic wastewater and the bioremediation of organic pollutants-contaminated sites. This paper introduced the research progress on the degradation of organic pollutants by thermophiles in terms of the characteristics of thermophiles in degrading organic pollutants, the effects of temperature on the degradation, the degradation pathways, the degradation enzymes, their coding genes, and practical engineering applications. The future research directions including the degradation mechanisms of thermophiles, their resources reserve, related technology strategies and their applications were also prospected.

Objective: Using 16S rDNA and 23S rDNA genes as the target sequences to develop a system based on oligonucleotide microarray and to detect the seven clinical pathogenic bacteria, commonly seen., Methods: Double polymerase chain reaction (PCR) was applied to amplify the segments of 16S rDNA and 23S rDNA genes of the target bacteria. An oligonucleotide microarray was constructed to simultaneously detect EHEC O157:H7, Vibrio parahaemolyticus, Salmonella sp., Vibrio cholerae, Listeria monocytogenes, Campylobacter jejuni and Shigella sp. Specificity, sensitivity and reproducibility of the microarray during detection were checked. And then microarray was used to detect the microbes in stool specimens of 81 patients with diarrhea and vomiting., Results: The double PCR method could simultaneously amplify the target sequences of 16S rDNA and 23S rDNA genes of the seven pathogens. The sensitivity of the developed oligonucleotide microarray could reach 10(3) cfu/ml but no positive results were presented for non-targeted bacteria. The coefficients of differentiation in one lot or among different lots of the microarray slices were 3.89% - 5.81%. The positive detection rate of the stool specimens by oligonucleotide microarray was 39.5% (32/81), with a coincidence of 96.3% (78/81) for the patients and another coincidence of 96.8% (31/32) for bacterial genus or species identification, when comparing to the results by routine bacteriological examinations., Conclusion: The established assay in this study based on oligonucleotide microarray to detect the seven pathogenic bacteria has many advantages such as convenient, rapid, accurate, stable and high flux, which is suitable for clinical specimen examination and epidemiological field investigation.