Extracellular laccase activity and transcript levels of putative laccase genes during removal of the xenoestrogen technical nonylphenol by the aquatic hyphomycete Clavariopsis aquatica

We investigated the influence of potential laccase inducers with environmental relevance on extracellular laccase activity and removal of the xenoestrogen technical nonylphenol (tNP) by the aquatic hyphomycete Clavariopsis aquatica. Concomitantly, we identified two putative laccase gene fragments (Icc1 and Icc2) and have followed their expression during removal of tNP under different conditions. Our results indicate a significant effect of copper on extracellular laccase activity in supernatants of fungal cultures. Laccase activity was highest in the presence of copper when added together with vanillic acid, followed by copper when used alone. Only slight laccase activities were recorded in the presence of only vanillic acid, whereas in the absence of either compound laccase activities were negligible. Laccase activity was well correlated with the removal efficiency of tNP, indicating the involvement of laccase in tNP bioconversion. Overall, Icc2 was less expressed than Icc1. The expression of Icc1 and Icc2 correlated only partially with the measured laccase activity, suggesting the existence of cell-associated laccase fractions not detectable in fungal culture supernatants and/or the existence of additional laccase genes.     

Genotoxicity assessment in aquatic environments under the influence of heavy metals and organic contaminants

The genotoxicity of river water and sediment including interstitial water was evaluated by microscreen phage-induction and Salmonella/microsome assays. Different processes used to fractionate the sediment sample were compared using solvents with different polarities. The results obtained for mutagenic activity using the Salmonella/microsome test were negative in the water and interstitial water samples analysed using the direct concentration method. The responses in the microscreen phage-induction assay showed the presence of genotoxic or indicative genotoxic activity for at least one water sample of each site analysed using the same concentration method. Similar results were obtained for interstitial water samples, i.e. absence of mutagenic activity in the Salmonella/microsome test and presence of genotoxic activity in the microscreen phage-induction assay. Metal contamination, as evidenced by the concentrations in stream sediments, may also help explain some of these genotoxic results. Stream sediment organic extracts showed frameshift mutagenic activity in the ether extract detected by Salmonella/microsome assay. The concentrates evaluated by microscreen phage-induction assay identified the action of organic compounds in the non-polar, medium polar and polar fractions. Thus, the microscreen phage-induction assay has proven to be a more appropriate methodology than the Salmonella/microsome test to analyse multiple pollutants in this ecosystem where both organic compounds and heavy metals are present.     

Genotoxicity assessment in aquatic environments under the influence of heavy metals and organic contaminants

The genotoxicity of river water and sediment including interstitial water was evaluated by microscreen phage-induction and Salmonella/microsome assays. Different processes used to fractionate the sediment sample were compared using solvents with different polarities. The results obtained for mutagenic activity using the Salmonella/microsome test were negative in the water and interstitial water samples analysed using the direct concentration method. The responses in the microscreen phage-induction assay showed the presence of genotoxic or indicative genotoxic activity for at least one water sample of each site analysed using the same concentration method. Similar results were obtained for interstitial water samples, i.e. absence of mutagenic activity in the Salmonella/microsome test and presence of genotoxic activity in the microscreen phage-induction assay. Metal contamination, as evidenced by the concentrations in stream sediments, may also help explain some of these genotoxic results. Stream sediment organic extracts showed frameshift mutagenic activity in the ether extract detected by Salmonella/microsome assay. The concentrates evaluated by microscreen phage-induction assay identified the action of organic compounds in the non-polar, medium polar and polar fractions. Thus, the microscreen phage-induction assay has proven to be a more appropriate methodology than the Salmonella/microsome test to analyse multiple pollutants in this ecosystem where both organic compounds and heavy metals are present.     

Concurrent removal and accumulation of heavy metals by the three aquatic macrophytes

Under the present investigation effectiveness of three aquatic macrophytes Pistia stratiotes L. (water lettuce), Spirodela polyrrhiza W. Koch (duckweed) and Eichhornia crassipes were tested for the removal of five heavy metals (Fe, Zn, Cu, Cr and Cd). These plants were grown at three different concentrations (1.0, 2.0 and 5.0mgl(-1)) of metals in laboratory experiment. Result revealed high removal (>90%) of different metals during 15 days experiment. Highest removal was observed on 12th day of experiment, thereafter it decreased. Results revealed E. crassipes as the most efficient for the removal of selected heavy metals followed by P. stratiotes and S. polyrrhiza. Results from analysis confirmed the accumulation of different metals within the plant and a corresponding decrease of metals in the water. Significant correlations between metal concentration in final water and macrophytes were obtained. Plants have accumulated heavy metals in its body without the production of any toxicity or reduction in growth. Selected plants shown a wide range of tolerance to all of the selected metals and therefore can be used for large scale removal of heavy metals from waste water.     

Toxicity, accumulation, and removal of heavy metals by three aquatic macrophytes

A comprehensive understanding of the uptake, tolerance, and transport of heavy metals by plants will be essential for the development of phytoremediation technologies. In the present paper, we investigated accumulation, tissue and intracellular localization, and toxic effects of cadmium (Cd), lead (Pb), zinc (Zn), and copper (Cu) in three aquatic macrophytes (the angiosperms Lemna minor and Elodea canadensis, and the moss Leptodictyum riparium). We also tested and compared their capacity to absorb heavy metal from water under laboratory conditions. Our data showed that all the three species examined could be considered good bioaccumulators for the heavy metals tested. L. riparium was the most resistant species and the most effective in accumulating Cu, Zn, and Pb, whereas L. minor was the most effective in accumulating Cd. Cd was the most toxic metal, followed by Pb, Cu, and Zn. At the ultrastructural level, sublethal concentrations of the heavy metals tested caused induced cell plasmolysis and alterations of the chloroplast arrangement. Heavy metal removal experiments revealed that the three macrophytes showed excellent performance in removing the selected metals from the solutions in which they are maintained, thus suggesting that they could be considered good candidates for wastewaters remediation purpose.     

Accumulation of heavy metals by aquatic mosses. 2: Rhynchostegium riparioides

A study was made of general ecology and metal accumulation in the widespread aquatic moss Rhynchostegium riparioides, (Hedw.) C. Jens. with a view to developing the use of this species as a monitor of heavy metal pollution. In order to establish a data bank for statistical analysis, samples of water and moss were taken within a 6-week period from 105 sites (10-m reaches) in Northern England from streams and rivers of diverse physical and chemical types. Analyses were made of 14 metals (Na, Mg, K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Ba, Pb) in both 2-cm tips and whole plants. The same 14 metals were also measured in both total and filtrable water, together with 12 other variables. Samples of tips were easier to prepare for analysis, but had significantly (p < 0.001) lower concentrations of all metals except Na and K. Significant correlations (p < 0.001) between metal in moss and aqueous metal were found for ten metals (Na, K, Mg, Ca, Mn, Cu, Zn, Cd, Ba, Pb). Correlations between metals in moss and in water were in general similar for tips and whole plants, but much higher for tips with Na, Zn and Cd; the relationship was quite similar whether total or filtrable water was considered, with the exception of Ba where the correlation was much higher with the latter. A multiple regression was used to suggest which variables in water and/ or moss may influence accumulation of Co, Ni, Cu, Zn, Cd, Ba and Pb in the moss. For instance, the variables which had a very highly significant effect on Pb in tips were Pb, filtrable reactive phosphate and Zn in the water. A discussion is included of how the data may be used for monitoring purposes.     

Accumulation of heavy metals by aquatic mosses. 3: Seasonal changes

The changes taking place at seven stream and river sites over a 14-month period were followed for the following:

1. % cover of Rhynchostegium riparioides;
2. relative abundance of Rhynchostegium as part of the whole plant community and, where present, also Amblystegium riparium and Fontinalis antipyretica;
3. 18 water chemistry variables;
4. concentrations of nine metals in 2-cm tips of Rhynchostegium at all sites and of Amblystegium and Fontinalis at one site each.

A decrease in the amounts of these mosses occurred in winter at most sites, the effect being most pronounced with Amblystegium. Nevertheless the majority of plants which remained had healthy shoots suitable for sampling for metal analysis at all times of year. There were marked temporal changes in the concentrations of metals in the 2-cm tips at each site, but few of these appeared to be related to seasonal events. The most plausible was for Pb in Rhynchostegium at a main river site, where increased accumulation in winter was probably an indirect effect of other chemical differences in the water during a period of high flows. Provided healthy shoots were available, there was no indication of seasonal differences in metal accumulation resulting from features of the mosses themselves.     

The utilization of dissolved organic compounds in aquatic environments

The uptake of dissolved organic matter by bacteria, phytoplankton and invertebrates is discussed referring to the literature. In natural waters the uptake of dissolved organic compounds appears to be primarily a bacterial process. Communication nr. 145 of the Delta Institute for Hydrobiological Research, Yerseke, The Netherlands     

Ecological functions of volatile organic compounds in aquatic systems

In terrestrial ecosystems, volatile organic compounds (VOCs) are widely acknowledged as an important group of infochemicals. They play a major role in pollinator attraction by terrestrial plants and as insect pheromones. Furthermore, they are the mediating agent of so-called 'tritrophic interactions'. When plants are attacked by herbivorous insects, volatile signal substances are emitted, which act as attractants for parasitoids that kill the herbivores, thereby protecting the plant from herbivory. Despite the generally acknowledged importance of VOCs in terrestrial chemical ecology, their functions in aquatic food webs are largely unknown. VOCs produced by algae and cyanobacteria are a major concern in water processing, since aquatic primary producers are the reason for regularly encountered taste and odour problems in drinking water. Only very recently, research in aquatic chemical ecology has started to investigate possible ecological functions for the production of VOCs by algae and cyanobacteria. Volatile aldehydes released by wounded cells of marine planktonic diatoms seem to act as defensive compounds against herbivorous copepods on the population level. Just recently, it was found that VOCs released from benthic algae and cyanobacteria can be utilised as food and/or habitat finding cues by aquatic invertebrates such as freshwater gastropods and nematodes. Here, I review concepts and recent experimental studies on the ecological functions of such VOCs in aquatic ecosystems. Understanding the factors that lead to the liberation of volatile compounds is an essential prerequisite to properly assessing their ecological functions. It appears that (similar to terrestrial plant-herbivore interactions) VOCs can also play a steering role for both attraction and defence in aquatic ecosystems.     

有机物及重金属植物修复研究进展

植物修复技术是近年来发展起来的一种非常有前途的生物治理技术 ,也是当前学术界研究的热点领域 .本文对植物修复的类型 ,植物修复土壤、水体有机污染物、重金属和某些放射性核素的过程、机理及可能影响因子作了概括和详尽讨论 ,并就国内外近年来植物修复技术在污染环境中的应用和研究成果进行了综述     

Oxidation of aromatic compounds in organic solvents with laccase from Trametes versicolor

Summary Laccase purified from Trametes versicolor oxidizes 2,6-dimethoxyphenol (2,6-DMP) and syringaldazine in hydrophobic solvents presaturated with water, and in hydrophilic organic solvents provided that a sufficient amount of water is added. Ease of performance of the laccase test in organic solvents is improved after immobilization of the enzyme by entrapping in Sepharose CL-6B during enzyme filtration through the gel beads. The gel-enzyme association has been shown to be stable in water-presaturated solvents. Efficiency of the immobilized laccase in organic solvents containing 7% water was 10%–20% of that in potassium-citrate buffer. Immobilized laccase in organic solvents showed good stability and high tolerance to elevated temperatures.     

Bioremediation of wastewaters with recalcitrant organic compounds and metals by aerobic granules

Compared to activated sludge flocs, aerobic granules have a regular shape, and a compact and dense structure which enhances settleability, higher biomass retention, multi-microbial functions, higher tolerance to toxicity, greater tolerance to shock loading, and relatively low excess sludge production. The potential for improved process efficiency and cost-effectiveness can be attractive when it is applied to both municipal and industrial wastewaters. This review discusses potential applications of aerobic granulation technology in wastewater treatment while drawing attention to relevant findings such as diffusion gradients existing in aerobic granules which help the biomass cope with inhibitory compounds and the ability of granules to continue degradation of inhibitory compounds at extreme acid and alkaline pHs.     

Distribution and assessment of heavy metals in the aquatic environment of Lake Manzala,Egypt

Analysis of trace metals from sediment and fish collected from eight locations in Lake Manzala, Egypt, during May, June and July of 2011, indicated anthropogenic impacts. The highest concentrations of metals, except Mn and Sr, were detected at Bahr Al-Baqar (S1) which drains from Cairo. At the other sampling locations, the concentrations of selected trace metals fall below the levels of concern while the geo-accumulation index (I_geo) suggests unpolluted conditions for the majority of the studied metals at most sites. However, near the Bahr Al-Baqar (S1) drain concentrations of Ag, Hg and Zn fall above the Long and Morgan's (1990) effects range low (ERL) while Pb was above their effects range median (ERM). I_geo values suggest unpolluted to moderately polluted condition for As and Sn, moderately polluted conditions for Zn, moderate to extremely polluted conditions for Ag, and severely to extremely polluted conditions for Pb at Bahr Al-Baqar. Two sites (Legan, S5, and Al-Ginka, S8) were indicated by I_geo as moderately polluted for Ag while two other sites (West of Bashar, S3, and Al Dehdy, S6) were indicated as unpolluted to moderately polluted for Ag. The Legan and Al-Ginka sites were also indicated as being moderately polluted for Zn. Similar to the sediments, the highest concentrations of metals in fish tissue were from Bahr Al-Baqar (S1). Al concentrations at all sites were comparable to concentrations known to cause lesions in fish. At all sites concentrations of selected trace metals in fish tissue were below the limits set by the FAO.