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Ademola O. Olaniran Nokukhanya H. Mfumo Dorsamy Pillay Balakrishna Pillay 《Biotechnology and Bioprocess Engineering》2006,11(3):205-210
The widespread use and distribution of chloroethylene organic compounds is of serious concern owing to their carcinogenicity
and toxicity to humans and wildlife. In an effort to develop active bacterial consortia that could be useful for bioremediation
of chloroethylenecontaminated sites in Africa, 16 combinations of 5 dichloroethylene (DCE)-utilizing bacteria, isolated from
South Africa and Nigeria, were assessed for their ability to degradecis- andtrans-DCEs as the sole carbon source. Three combinations of these isolates were able to remove up to 72% of the compounds within
7 days. Specific growth rate constants of the bacterial consortia ranged between 0.465 and 0.716 d−1 while the degradation rate constants ranged between 0.184 and 0.205 d−1, with 86.36–93.53 and 87.47–97.12% of the stoichiometric-expected chloride released during growth of the bacterial consortia,
incis- andtrans-DCE, respectively. Succession studies of the individual isolates present in the consortium revealed that the biodegradation
process was initially dominated byAchromobacter xylosoxidans and subsequently byAcinetobacter sp. andBacillus sp., respectively. The results of this study suggest that consortia of bacteria are more efficient than monocultures in the
aerobic biodegradation of DCEs, degrading the compounds to levels that are up to 60% below the maximum allowable limits in
drinking water. 相似文献
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Effects of Erosion from Mounds of Different Termite Genera on Distinct Functional Grassland Types in an African Savannah 总被引:1,自引:0,他引:1
A key aspect of savannah vegetation heterogeneity is mosaics formed by two functional grassland types, bunch grasslands, and
grazing lawns. We investigated the role of termites, important ecosystem engineers, in creating high-nutrient patches in the
form of grazing lawns. Some of the ways termites can contribute to grazing lawn development is through erosion of soil from
aboveground mounds to the surrounding soil surface. This may alter the nutrient status of the surrounding soils. We hypothesize
that the importance of this erosion varies with termite genera, depending on feeding strategy and mound type. To test this,
we simulated erosion by applying mound soil from three termite genera (Macrotermes, Odontotermes, and Trinervitermes) in both a field experiment and a greenhouse experiment. In the greenhouse experiment, we found soils with the highest macro
nutrient levels (formed by Trinervitermes) promoted the quality and biomass of both a lawn (Digitaria longiflora) and a bunch (Sporobolus pyramidalis) grass species. In the field we found that soils with the highest micro nutrient levels (formed by Macrotermes) showed the largest increase in cover of grazing lawn species. By linking the different nutrient availability of the mounds
to the development of different grassland states, we conclude that the presence of termite mounds influences grassland mosaics,
but that the type of mound plays a crucial role in determining the nature of the effects. 相似文献
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