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ABSTRACT: Purple phototrophic bacteria (PPB) are thought to be crucial in the nutrient cycling of rice field. However, it remains unclear
how PPB would respond to the climate change associated with the projected atmospheric CO2 in the future. A factorial design of field experiments was set up with two levels of atmospheric CO2 concentration (350 and 550μmol mol−1) and N application rate (150 and 250kg N ha−1) to investigate the abundance and composition changes of PPB in rhizospheric and bulk soils in response to the rising atmospheric
CO2 concentration. Based on denaturant gradient gel electrophoresis (DGGE) analysis of pufM gene encoding the M subunit of anoxygenic PPB light reaction center, elevated CO2 appeared to enhance the biodiversity of PPB in flooded paddy soils. This was further supported by canonical correspondence
analysis (CCA) of DGGE fingerprinting pattern of pufM genes in paddy soils as well as Shannon diversity indices. Real-time quantitative PCR analysis of pufM gene further indicated that PPB abundance was stimulated by elevated CO2 in bulk soil, while the contrasting result was observed in rhizospheric soil. Our result for the first time demonstrated
that elevated CO2 enhanced the biodiversity of PPB within α and β subdivisions of Proteobacteria.
Plant and Soil 04/2012; 324(1):317-328. · 2.73 Impact Factor
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ABSTRACT: The effectiveness of in-situ bioremediation of polycyclic aromatic hydrocarbons (PAHs) may be inhibited by low nutrients and organic carbon. To evaluate the effect of organic wastes on the PAHs removal efficiency of a plant-microbe remediation system, contaminated agricultural soils were amended with different dosages of sewage sludge (SS) and cattle manure (CM) in the presence of alfalfa (Medicago sativa L.) and PAHs-degraders (Bacillus sp. and Flavobacterium sp.). The results indicated that the alfalfa mean biomasses varied from 0.56 to 2.23 g/pot in root dry weight and from 1.80 to 4.88 g/pot in shoot dry weight. Low dose amendments, with rates of SS at 0.1% and CM at 1%, had prominent effects on plant growth and soil PAHs degradation. After 60-day incubation, compared with about 5.6% in the control, 25.8% PAHs removal was observed for treatments in the presence of alfalfa and PAHs-degraders; furthermore, when amended with different dosages of SS and CM, the removed PAHs from soils increased by 35.5%-44.9% and 25.5%-42.3%, respectively. In particular, the degradation of high-molecular-weight PAHs was up to 42.4%. Dehydrogenase activities (DH) ranged between 0.41 and 1.83 microg triphenylformazan/(g dry soil x hr) and the numbers of PAHs-degrading microbes (PDM) ranged from 1.14 x 10(6) to 16.6 x 10(6) most-probable-number/g dry soil. Further investigation of the underlying microbial mechanism revealed that both DH and PDM were stimulated by the addition of organic wastes and significantly correlated with the removal ratio of PAHs. In conclusion, the effect of organic waste application on soil PAHs removal to a great extent is dependent on the interactional effect of nutrients and dissolved organic matter in organic waste and soil microorganisms.
Journal of Environmental Sciences 01/2012; 24(8):1476-82. · 1.66 Impact Factor
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ABSTRACT: Salmonella causes the majority of infections in humans and homeothermic animals. This article describes a specific polymerase chain reaction (PCR) method developed for a rapid identification of Salmonella. A gyrB-targeted species-specific primer pair, S-P-for (5'-GGT GGT TTC CGT AAA AGT A-3') and S-P-rev (5'-GAA TCG CCT GGT TCT TGC-3'), was successfully designed. PCR with all the Salmonella strains produced a 366- bp DNA fragment that was absent from all the non-Salmonella strains tested. The detection limit of the PCR was 0.01 ng with genomic DNA or 3.2 cells per assay. Good specificity was also demonstrated by fecal samples, from which only the gyrB gene of Salmonella was amplified. Using the culture-PCR method, 27 isolates on Salmonella-Shigella (SS) medium were rapidly identified as Salmonella, which was confirmed by the sequencing of the gyrB gene.
Current Microbiology 09/2011; 63(5):477-83. · 1.82 Impact Factor
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ABSTRACT: Livestock manure heaps and wetland rice fields are major sources of CH4 emissions. A field experiment with an associated composting study were undertaken to investigate CH4 emissions during manure composting and subsequent land application on paddy. Over a 24-day period in the composting experiment, CH4 emissions from stored manure was 17 times higher than that from composting manure, indicating that composting as an aerobic process was effective in mitigating CH4 emissions compared with manure storage, which is normally under an anaerobic environment. Stored and composted manures were subsequently applied as organic fertilizers in the field experiment. Compared with the non-fertilized control treatment, stored and composted manures increased grain yields by 30% and 21%, respectively. During the full rice-growing season, the cumulative CH4 emission was 15.8 g CH4/m2 with the application of composted manure, only one-third of that from stored manure. CH4 emission per unit of grain yield was significantly decreased by composted manure, with a reduction of 56% from the control and 73% from stored manure. The results indicate that composted livestock manure in rice cultivation is a triple-win option through sustaining rice yield, mitigating CH4 emissions and re-utilizing livestock waste.
Soil Use and Management 02/2011; 27(1):103 - 109. · 1.61 Impact Factor
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ABSTRACT: Biosorption has been shown to be an eco-friendly approach to remove heavy metal ions. In this study, the photosynthetic bacteria Rhodobacter capsulatus was screened and found to have strong ability to adsorb Au(III). The maximum specific uptake of living cells was over 92.43 mg HAuCl(4)/g dry weight of cell in the logarithmic phase. Biosorpion ability would be enhanced by an acidic environment. As the main cations, during biosorption the quantity of Mg(2+) exchanged was more than Na(+). Biosorbed Au(III) could be reduced by carotenoid and enzymes embedded and/or excreted by R. capsulatus, which might be the mechanism of photosynthtic bacteria metal tolerance.
Current Microbiology 12/2007; 55(5):402-8. · 1.82 Impact Factor
