ABSTRACT
SYBR Green I Real Time-qPCR method was developed to quantify the numbers of copyies of AlkB ( alkanes degradation gene) and Nah ( naphthalene dioxygenase degradation gene) functional degradation gene corresponding to alkanes and aromatic hydrocarbons degradation. Two pairs of primers AlkBf/AlkBr and Nahf/Nahr were designed for AlkB and Nah amplification respectively, according to the nucleotide sequences of related degradation microorganisms published in GenBank. The purified recovery products of traditional PCR were combined with pEASY-T1 vectors and transformed in competent cells to amplify. The recombinant plasmids were extracted and used as positive templates to create standard curve through gradient dilution. The conditions for the real time PCR were as the follows: the final concentration of forward and reverse primers were 0. 2 μmol/L, 2×TransStart Top Green qPCR SuperMix, and the annealing temperatures of AlkB and Nah PCR were 50℃ and 57℃, respectively. The method showed a sensitivity of 100 times higher than that of the traditional PCR method and good repeatability. The numbers of copies of AlkB in three functional regions of an oilfield indicated that oil producing zone with serious oil pollution had the highest AlkB copy numbers, and residential zone with lighter oil pollution had the lowest AlkB copy numbers. Nah degradation gene distribution was more uniform.
ABSTRACT
Microbial fuel cell (MFC) is a new technology that can recover energy from biomass with simultaneous waste treatment. This technique has been developed fast in recent years in combining with environmental techniques such as wastewater treatment, degradation of toxic pollutants and desalination. With the increase of solid waste, applying MFC in composting is promising due to its property of waste disposal with simultaneous energy generation. In this paper, the microbial community of MFCs during composting was summarized. Four major influencing factors including electrodes, separators, oxygen supplement and configurations on the performance of composting MFCs were discussed. The characteristics of composting MFC as a new technique for reducing solid waste were as follows: high microbial biomass resulted in the high current density; adaptable to different environmental conditions; self-adjustable temperature with high energy efficiency; the transportation of proton from anode to cathode were limited by different solid substrates.
Subject(s)
Bioelectric Energy Sources , Microbiology , Electricity , Electrodes , Refuse Disposal , MethodsABSTRACT
The influencing factors of ultrasonic extraction(UE) and ultrasonic-soxhlet extraction(USE) were analyzed based on orthogonal experimental design. The optimum analytical conditions of two methods were determined. The three different methods: UE, USE and traditional soxhlet extraction(SE) were compared by simultaneous analysis with three different soil samples: fresh contaminated soil, soil after microbial remediation and soil after phytoremediation. The optimum condition of the UE was extracting 4 times with chloroform, 15 mL extractant every time. The optimum condition of the USE method was ultrasonic for 10 min at 60 W, followed by soxhlet extraction with 125 mL extractant for 6 h. Compared the three different methods, USE method showed the best result with the highest average extraction rate of 102.98%, the UE method with average extraction rate of 99.69%, and the SE method with low average extraction rate of 97.31%. The research indicates that USE method is effective in determining soil total petroleum hydrocarbons(TPH) within shorter time and higher efficiency and can be used as a method for determining TPH content in different soils.