Papers by Keyword: PCR-DGGE

Abstract: 16SrDNA PCR-DGGE was used to reveal the dynamics of bacterial colony and identify the predominant bacteria in liquid-smoked tilapia during storage at 25°C. Total bacteria DNA was directly extracted from the tilapia fillets. By analysis of the community changes directly obtained from the DGGE profiles, the predominant bacteria were found to be Pediococcus pentosaceus, Clostridium sp. and Lactococcus garvieae. Simultaneously, culture method was performed., 34 strains of 70 colonies were picked up from samples of day 4 storage period, then 6 strains were picked up at random and identified by extracting their 16SrDNA and sequencing, it’s proved that they were all Lactococcus. So Two ways of identifying the predominant bacteria were almost consistent.

Abstract: The soil bacteria diversity in different concentrations of CO₂ was investigated in the simulation test area, by using PCR (Polymerase Chain Reaction) -DGGE (Denaturing Gradient Gel Electrophoresis) and 16Sr-DNA library technology. The results showed that the bacteria diversity coefficient (P) got down to 0.8710, 0.8710 and 0.7742 from 0.9032 (from control area) when the concentration of CO₂ in soil reached 20000ppm, 40000ppm, 60000ppm respectively. With the increasing concentration of CO₂ in soil, the abundance of the original low-density bacteria such as Asticcacaulis excentricus, etc. increased, while the abundance of unclassified_Rhizobiales reduced significantly. Dominant bacteria such as Brucella melitensis etc. had the higher homology. It can be revealed that high concentration of CO₂ had a significant impact on the soil bacteria community diversity, while a weak influence on main bacterial species. Azotobacter was sensitive to the increasing of the CO₂ concentration. Great reducing of their abundance had an adverse effect on nitrogen-fixing capability of soil.

Abstract: To identify the intestinal microflora diversity of transgenic sheep and non-transgenic one with overexpression of foreign antiviral gene (VP1 & SB-SW), DNA of total bacteria were extracted from 16 sheep fecal samples (4 non-transgenic sheep, 6 VP1 transgenic sheep and 6 SB-SW transgenic sheep). And then PCR amplification with bacterial universal primers of V3 variable region of 16S rRNA were taken to get the fingerprint profile by denaturing gradient gel electrophoresis (DGGE) technology. The results showed that the DGGE profiles of the 16 fecal samples were highly polymorphic. The number of DGGE bands, considered indicative of the total species richness, did not vary predictably among the three different samples. The DNA sequences were analyzed and the dominant bacteria in sheep fecal were found to be Bacteroides, Clostridium, and Ruminococcus. Specially, non-transgenic sheep had more Alistipes finegoldii and Clostridium lentocellum, transgenic sheep with VP1 had more Clostridium drakei and Clostridium populeti and transgenic sheep with SB-SW had more Barnesiella intestinihominis and Clostridium ljungdahlii. So the PCR-DGGE technique can be applied to evaluate genetically modified (GM) animal potential risks to the environment.

Abstract: To investigate nutrient removal and biological community structure in wastewater treatment system under different ratio of C/N/P, hybrid biofilm reactor (HBR) and sequencing batch reactor (SBR) in lab scale were set up. Results showed that both HBR and SBR achieved the best removal efficiency of nitrogen and phosphorus when C/N/P=100/6.25/1. With the rise of C/N/P from 50/6.25/1 to 100/6.25/1, the removal efficiencies of NH₃-N were greater than 93% in three phases of both reactors; the efficiencies of TN were increased from 65% to 79% in SBR while these values at HBR were from 73% to 86%; the efficiencies of TP were increased from 42% to 93% in SBR while these values at HBR were from 32% to 93%. Microbial community structure response to different C/N/P was determined by PCR-DGGE technology. Similarity coefficient was lowest and denitrifying phosphate accumulating bacteria became dominant bacteria in SBR when C/N/P was 100/6.25/1. There were many functional bacteria in HBR, such as bacteria for removing nutrients (Uncultured BacteroidetesFJ828150), bacteria for removing organic (Uncultured Saprospiraceae) bacteria for removing nitrogen (Ferribacterium sp.), and nitrifying bacteria (Uncultured Nitrospira sp.) which became dominant bacteria. Because of microbial diversity index of biofilm was up to 3.3, similarity coefficient was as low as 43.4%.

Abstract: To improve the efficiency of oily wastewater purification, a laboratory-scale anaerobic/anoxic/aerobic (A2O) membrane bioreactor was designed to treat the oily wastewater based on the conventional A2O activated sludge process and membrane separation technology, and the variation of bacterial community structure in the activated sludge of key reactors were investigated by PCR-DGGE (denaturing gradient gel electrophoresis). The result of Shannon diversity index comparing indicated that MBR seemed to be more constant than the A/0 system. Four sensitive dominant bacteria were verified in the treatment of oily wastewater. They were Uncultured Comamonadaceae bacterium, Hydrogenophaga sp., uncultured beta proteobacterium, and uncultured Thiobacillus sp. It suggested that PCR-DGGE can be used as an effective supplementary method for verifying cultural dominant microorganisms in activated sludge of oily wastewater.

Abstract: In this study, the effect of environment materials for civil engineering was investigated through two sets of parallel reactors with sodium acetate and starch as carbon source separately. The reactors were started up by two stages, including biofilm formation stage and biofilm domestication stage. In biofilm domestication stage, the average removal efficiencies of COD were 88.84% and 88.78% respectively. NH4+-N removal efficiencies were reached at 99.28% and 91.90%. Total nitrogen（TN）removal efficiencies were 45.25% and 45.45%. By PCR-DGGE, it was found that there were high similarities between biofilm and suspension in the reactors. Different types of carbon sources enriched different types of microorganisms. The study can provide references for studying simultaneous nitrification and denitrification（SND）and optimizing carbon sources.

Abstract: In this study, the main microbe dynamic changes of cutlassfish (Trichiurus haumela) treated with composite natural preservatives under the cold storage (4±1) °C were studied by the methods of culture-dependent and denaturing gradient gel electrophoresis (DGGE) fingerprinting analysis based on the sequence of 16S rRNA V3 region gene, which provided the theory basis and reference to the composite natural preservatives’ mechanism and extended the shelf-life of aquatic products. The results showed that 13 kinds of bacteria were identified by the culture-dependent methods, the dominant bacteria belonged to Shewanella putrefaciens and Pseudomonas fluorescens. By sequencing analysis, 12 kinds of bacteria in main DGGE spectra stripe of cutlassfish. In the later periods, the specific spoilage organism (SSO) for the treatment group with composite natural preservatives and the controlled of cutlassfish were highly similar. Psychrobacter sp. was the main bacterium in the initial stage of the storage. With the extension of storage time, the proportion of Shewanella sp. and Pseudomonas sp. increased gradually and they took the place of Psychrobacter sp. to be the dominant bacteria in the process of storage. Thereinto, Pseudomonas fluorescens and Vibrio sp. both took high proportions in the process of storage. At the same time, composite natural preservatives had an obvious growth inhibition effects on the bacteria of cutlassfish such as Shewanella sp. and Pseudomonas sp..

Abstract: This study applies PCR-DGGE fingerprinting technique to analysis the bacterial community structure of phosphorous removal and denitrification system. Through strains identification, it is found that acinetobacter sp.is the base of keeping favorable phosphorus removal effect, Spirochaeta sp.undertakes the function of organic matters removal, Bacillus sp. and Lampropedia hyalina sp.can propagate largely in the germiculture area(No.1 oxic tank), and can be preyed on by highlevel microbe(such as protozoa and metazoan) in protozoa growing area(No.2oxic tank) and metazoan growimg area(No.3 oxic tank). The predation between highlevel microbe and low grade microbe can promote efficient sludge reduction of HA-A/A-MCO process.

Abstract: Bacterial community structure of advanced HA-A/A-MCO sludge reduction process is analyzed by DGGE fingerprinting technology. Research results indicates that microbial flora showed the distinction of highly diversity in anaerobic tank, anoxic tank and MCO tank of the HA-A/A-MCO process, and each tank has its own diversified and stable dominant microorganisms, as so the co-activation of such preponderant bacterial community promotes the system to exert favourable and consistent function of phosphorous and nitrogen removal and sludge reduction.

Abstract: To reveal the succession procedure of microbial community in hybrid biological reactor (HBR), the molecular biological techniques of polymerase chain reaction-denaturing gel gradient electrophoresis (PCR-DGGE), cloning and sequencing and fluorescence in situ hybridization (FISH) were applied. PCR-DGGE results showed that the microbial community accumulated in both suspended-growth and attached-growth biomasses. Proteobacteria was found to be the dominant genera of bacteria in the sludge. Denitrifying bacteria was found accumulated in the biofilms. FISH results showed that there were more nitrifying bacteria in the suspended-growth biomass than the attached-growth biomass, but less denitrifying bacteria in the former biomass.