Systematic site survey for sample collection and analysis was conducted at a derelict copper (Cu) mine at Kapunda, South Australia. Cu concentrations in the soils at this former mine ranged from 65–10107 mg kg?1. The pH and EC varied widely in the 3.9–8.4 and 152–7311 µS ranges, respectively. Nine plant species growing over the copper mine site were selected to screen for metal uptake to determine their suitability for phytoremediation. The Australian native tree species Eucalyptus camaldulensis indicated enrichment factor (EF) of 2.17, 1.89, and 1.30 for Cu, Zn, and Pb, respectively, suggesting that this species of tree can accumulate these metals to some degree. The stress-resistant exotic olive, Olea europaea exhibited EF of ≤ 0.01 for Cu, Cd, and Pb, and 0.29 for Zn, which is characteristic of an excluder plant. Acacia pycnantha, the Australian pioneer legume species with EF 0.03, 0.80, 0.32, and 0.01 for Cu, Zn, Cd, and Pb, respectively, emerged as another strong metal excluder and consequently as an ideal metal stabilizer. 相似文献
In order to remove heavy metals (HMs) from contaminated shrimp pond at the highest concentrations found of; 0.75 mg/l Cd2+, 62.63 mg/l Pb2+, 34.60 mg/l Cu2+ and 58.50 mg/l Zn2+, two strains of purple nonsulfur bacteria isolated from shrimp ponds (NW16 and KMS24) were investigated for their ability
to immobilize HMs in 3% NaCl in both microaerobic-light and aerobic-dark conditions. Based on metabolic inhibition and metabolic-dependent
studies, it was concluded that both strains removed HMs using biosorption and also bioaccumulation. The efficiency of removal
by both strains with both incubating conditions tested was in the order of lead (Pb) > copper (Cu) > zinc (Zn) > cadmium (Cd).
Optimal conditions for removal of HMs by strain NW16 were; cells in the log phase at 4.5 mg DCW/ml, pH 6.0, and 30°C for 30 min.
With microaerobic-light conditions, the relative percent removal of HMs was: Pb, 83; Cu, 59; Zn, 39; Cd, 23 and slightly more
with the aerobic-dark conditions (Pb, 90; Cu, 69; Zn, 46; Cd, 28). Cells in the log phase at 5.0 mg DCW/ml, pH 5.5, and 35°C
for 45 min were optimal conditions for strain KMS24 and there were no significant differences for the removal percentages
of HMs with either incubating conditions (averages: Pb, 96; Cu, 75; Zn, 46; Cd, 30). The presence of Ca2+ and Mg2+ significantly decreased the removal capacity of HMs for both strains. 相似文献
An Arthrobacter sp. and a Bacillus sp., isolated from a long-term tannery waste contaminated soil, were examined for their tolerance to hexavalent chromium
[Cr(VI)] and their ability to reduce Cr(VI) to Cr(III), a detoxification process in cell suspensions and cell extracts. Both
bacteria tolerated Cr(VI) at 100 mg/ml on a minimal salts agar medium supplemented with 0.5% glucose, but only Arthrobacter could grow in liquid medium at this concentration. Arthrobacter sp. could reduce Cr(VI) up to 50 μg/ml, while Bacillus sp. was not able to reduce Cr(VI) beyond 20 μg/ml. Arthrobacter sp. was distinctly superior to the Bacillus sp. in terms of their Cr(VI)-reducing ability and resistance to Cr(VI). Assays with permeabilized (treated with toluene or
Triton X 100) cells and crude extracts demonstrated that the Cr(VI) reduction was mainly associated with the soluble protein
fraction of the cell. Arthrobacter sp. has a great potential for bioremediation of Cr(VI)-containing waste.
Received: 13 June 2002 / Accepted: 13 September 2002 相似文献
Transgenic plants of rose-scented geranium (Pelargonium graveolens cv. Hemanti) have been produced from Agrobacterium rhizogenes (strains A4 and LBA9402) mediated hairy root cultures. Amongst the explants tested, leaves were most responsive followed by the petioles
and internodal segments, respectively. The A4 strain performed better for all the three explants both in terms of frequency of response and time requirement for hairy
root induction. Transgenic shoots could be obtained by spontaneous regeneration without intervening callus phase amongst 16%
and 12% root lines of A4 and LBA 9402 origin, respectively, or they were induced in 29% and 22% hairy root lines of A4 and LBA9402 origin, respectively, with different hormonal supplementation. These transgenic plants showed 30% survival as
against 90% of their control under the confined environment of glasshouse. The transgenic plants were of similar morphotype
having increased branching, higher number of leaves with increased dentations, short and round stature, highly branched root
system and absence of leaf wrinkling. These transgenic plants showed opine positive results even after 5 months of their transfer
to the glasshouse. The essential oil compositions of 81% of these transgenics were qualitatively similar to that of the wild
type parent. However, two transgenic plants (LZ-3 and 14TG) showed increase in concentrations of geraniol and geranyl esters
signifying improved oil quality with respect to the citronellol:geraniol ratio. These two oils having better olfactory value
represent an improvement over that of the wild type parent from the commercial point of view. 相似文献
A mixed culture of bacteria, enriched from soil collected at a coal gasification site, proved capable of removing the potent oestrogenic mycotoxin zearalenone from culture media. The bacteria grew rapidly when zearalenone was provided as the sole source of carbon and energy. HPLC and ELISA analysis of culture extracts revealed no zearalenone or zearalenone-like products. Fourteen bacterial isolates from the mixed culture were identified and purified. The ability to degrade zearalenone was lost upon purification and recombination of the bacterial members of the mixed culture. A strain of Pseudomonas fluorescens capable of degrading polychlorinated biphenyls was unable to degrade zearalenone. This is the first report of the complete degradation of zearalenone by bacteria. The present study suggests the potential of mixed cultures in the biodegradation of zearalenone. 相似文献
The dibenzo-p-dioxin(DD)- and dibenzofuran(DF)-degrading bacterium, Sphingomonas sp. strain RW1, was tagged by insertion of a mini-Tn5 lacZ transposon in order to follow its fate in complex laboratory soil systems. The tagged strain was tested for its ability to
survive in soil and degrade DF and DD applied at a concentration of 1 mg/g. Bacteria pre-adapted to soil conditions were found
to survive better in DF- and DD-amended soil and degrade the substrate more efficiently than bacteria that had not been subjected
to pre-adaptation. The concentration of soil-applied DF and DD, individually and in combination, decreased to less than 2%
of the original concentrations within 3 weeks of addition of the RW1 derivative, accompanied by a short, but significant exponential
increase in RW1 viable cells. During the same period the native bacterial population in soil was stable while viable fungi
declined.
Received: 12 November 1996 / Received revision: 21 February 1997 / Accepted: 22 February 1997 相似文献
This study evaluated the effect of inorganic mercury (Hg) on bacterial community and diversity in different soils. Three soils—neutral, alkaline and acidic—were spiked with six different concentrations of Hg ranging from 0 to 200 mg kg−1 and aged for 90 days. At the end of the ageing period, 18 samples from three different soils were investigated for bacterial community structure and soil physicochemical properties. Illumina MiSeq-based 16s ribosomal RNA (rRNA) amplicon sequencing revealed the alteration in the bacterial community between un-spiked control soils and Hg-spiked soils. Among the bacterial groups, Actinobacteria (22.65%) were the most abundant phyla in all samples followed by Proteobacteria (21.95%), Bacteroidetes (4.15%), Firmicutes (2.9%) and Acidobacteria (2.04%). However, the largest group showing increased abundance with higher Hg doses was the unclassified group (45.86%), followed by Proteobacteria. Mercury had a considerable negative impact on key soil functional bacteria such as ammonium oxidizers and nitrifiers. Canonical correspondence analysis (CCA) indicated that among the measured soil properties, Hg had a major influence on bacterial community structure. Furthermore, nonlinear regression analysis confirmed that Hg significantly decreased soil bacterial alpha diversity in lower organic carbon containing neutral and alkaline soils, whereas in acidic soil with higher organic carbon there was no significant correlation. EC20 values obtained by a nonlinear regression analysis indicated that Hg significantly decreased soil bacterial diversity in concentrations lower than several guideline values.