有机磷生物修复研究进展

目前,有机磷的生物修复还主要是微生物修复。但是植物修复更具优越性,因其花费更少、对环境更安全。然而植物对生长条件的要求相对较高,修复效率较低,应用还非常有限。本文综述了有机磷微生物修复和植物修复的研究进展,总结了已知的有机磷降解酶及其生物来源。结果表明,植物材料的筛选、土壤与OPs作用机理的研究、植物耐受和消除OPs的基因组学研究、植物-微生物联合降解体系的建立以及降解酶的植物根系分泌系统的利用是提高有机磷植物修复效率的重要途径。     

Bioremediation of glyphosate-contaminated soils

Based on the results of laboratory and field experiments, we performed a comprehensive assessment of the bioremediation efficiency of glyphosate-contaminated soddy-podzol soil. The selected bacterial strains Achromobacter sp. Kg 16 (VKM B-2534D) and Ochrobactrum anthropi GPK 3 (VKM B-2554D) were used for the aerobic degradation of glyphosate. They demonstrated high viability in soil with the tenfold higher content of glyphosate than the recommended dose for the single in situ treatment of weeds. The strains provided a two- to threefold higher rate of glyphosate degradation as compared to indigenous soil microbial community. Within 1–2 weeks after the strain introduction, the glyphosate content of the treated soil decreased and integral toxicity and phytotoxicity diminished to values of non-contaminated soil. The decrease in the glyphosate content restored soil biological activity, as is evident from a more than twofold increase in the dehydrogenase activity of indigenous soil microorganisms and their biomass (1.2-fold and 1.6-fold for saprotrophic bacteria and fungi, respectively). The glyphosate-degrading strains used in this study are not pathogenic for mammals and do not exhibit integral toxicity and phytotoxicity. Therefore, these strains are suitable for the efficient, ecologically safe, and rapid bioremediation of glyphosate-contaminated soils.     

石油烃污染土壤的生物修复

从中原油田污染土壤中通过实验室驯化培养分离到一组能以中原原油为碳源的快速生长的石油烃降解菌.用该组降解菌接种原油污染土壤,研究其原位生物联合修复实验,接种降解菌的各区分别种植大豆、施有机肥料、施有机肥料和锯末,与空白试样作对比.经过120d的联合修复,各区石油降解菌的总数(lgcfu/g)由接种时的5.25分别变为7.79、4.96、5.15、4.67.石油烃降解率分别达到89.4%、72.5%、76.7%、49.2%.表明分离的该组石油烃降解菌是一组高效降解菌且其与植物联合修复石油污染土壤能显著提高修复效果.     

Bioremediation of chromium contaminated environments

Bioremediation is the most promising and cost effective technology widely used nowadays to clean up both soils and wastewaters containing organic or inorganic contaminants. Discharge of chromium containing wastes has led to destruction of many agricultural lands and water bodies. Utilisation of chromium(Cr) reducing microbes and their products has enhanced the efficiency of the process of detoxification of Cr(VI) to Cr(III). This review focuses mainly on the current technologies prevalent for remediation like natural attenuation, anaerobic packed bed bioreactors (using live cells, Cr(VI) reductases or their byproducts) and use of engineered microorganisms. Treatment of wastewaters by biosorption or using biofilms and immobilized microbial cells are also discussed.     

Bioremediation of groundwater pollution.

Significant progress has been made in the past year towards an understanding of the microbial processes in subsurface environments that may allow natural microbial populations to be employed for bioremediation of groundwater pollution. Among the highlights were: the discovery of several previously unknown xenobiotic-degrading abilities in groundwater microorganisms; progress in using the unique abilities of methanotrophs to oxidize halogenated solvents; and characterizations of microbial populations from subsurface soils.     

中国水青冈分布,生长和更新特点

中国水青冈分布、生长和更新特点吴刚（中国科学院生态环境研究中心,北京１０００８５）Ｄｉｓｔｒｉｂｕｔｉｏｎ,ＧｒｏｗｔｈａｎｄＲｅｖｅｇｅｔａｔｉｏｎａｌＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆＦａｇｕｓｉｎＣｈｉｎａ．ＷｕＧａｎｇ（ＲｅｓｅａｒｃｈＣｅｎ...     

Heavy Metals Bioremediation of Soil

Historical emissions of old nonferrous factories lead to large geographical areas of metals-contaminated sites. At least 50 sites in Europe are contaminated with metals like Zn, Cd, Cu, and Pb. Several methods, based on granular differentiation, were developed to reduce the metals content. However, the obtained cleaned soil is just sand. Methods based on chemical leaching or extraction or on electrochemistry do release a soil without any salts and with an increased bioavailability of the remaining metals content. In this review a method is presented for the treatment of sandy soil contaminated with heavy metals. The system is based on the metal solubilization on biocyrstallization capacity of Alcaligenes eutrophus CH34. The bacterium can solubilize the metals (or increase their bioavailability) via the production of siderophores and adsorb the metals in their biomass on metal-induced outer membrane proteins and by bioprecipitation. After the addition of CH34 to a soil slurry, the metals move toward the biomass. As the bacterium tends to float quite easily, the biomass is separated from the water via a flocculation process. The Cd concentration in sandy soils could be reduced from 21 mg Cd/kg to 3.3 mg Cd/kg. At the same time, Zn was reduced from 1070 mg Zn/kg to 172 mg Zn/kg. The lead concentration went down from 459 mg Pb/kg to 74 mg Pb/kg. With the aid of biosensors, a complete decrease in bioavailability of the metals was measured.     

Influence of temperature and humidity on the survival of Monilinia fructicola conidia on stone fruits and inert surfaces

The survival of the fungus Monilinia fructicola on fruit and inert surfaces at different temperatures (range: 0–30°C) and relative humidity (RH) (range: 60–100%) was investigated. M. fructicola conidia survived better on fruit than on inert surfaces. The viability reduction rate at 20°C and 60% RH was 1.2 and 5.8 days^?1 on fruit and inert surfaces, respectively. Overall, on fruit surfaces, conidia viability was reduced at high temperatures and was longer at higher RH than at lower RH; in contrast, on inert surfaces, conidia viability was longer at only low temperatures. On fruit surfaces, at 0°C and 100% RH, conidia survived up to 35 days, and at 30°C and 60% RH, conidia survived up to 7 days. However, on inert surfaces at 20°C and 30°C, conidia lost their viability after 48 and 24 h, respectively. These results suggest that M. fructicola can remain viable in cold rooms for over 30 days on fruit surfaces or over 25 days on inert surfaces. Furthermore, under the orchard conditions during the growing season, conidia may remain viable for only 2–3 days on immature fruit surfaces before conidia will be unable to penetrate the host.     

Bioremediation of hydrocarbon-contaminated polar soils

Bioremediation is increasingly viewed as an appropriate remediation technology for hydrocarbon-contaminated polar soils. As for all soils, the successful application of bioremediation depends on appropriate biodegradative microbes and environmental conditions in situ. Laboratory studies have confirmed that hydrocarbon-degrading bacteria typically assigned to the genera Rhodococcus, Sphingomonas or Pseudomonas are present in contaminated polar soils. However, as indicated by the persistence of spilled hydrocarbons, environmental conditions in situ are suboptimal for biodegradation in polar soils. Therefore, it is likely that ex situ bioremediation will be the method of choice for ameliorating and controlling the factors limiting microbial activity, i.e. low and fluctuating soil temperatures, low levels of nutrients, and possible alkalinity and low moisture. Care must be taken when adding nutrients to the coarse-textured, low-moisture soils prevalent in continental Antarctica and the high Arctic because excess levels can inhibit hydrocarbon biodegradation by decreasing soil water potentials. Bioremediation experiments conducted on site in the Arctic indicate that land farming and biopiles may be useful approaches for bioremediation of polar soils.     

Bioremediation: A perspective

In this opinion paper, we offer our perspective on our bioremediation research along with the methods to assess its effectiveness as a safe and beneficial technology to remediate selected soil sites. The isolation and characterization of bacterial isolates from chemically contaminated soils, their survival and catabolic activity in contaminated soil, toxicity testing in chemically contaminated soils, molecular‐based methods of detection such as the polymerase chain reaction (PCR) and DNA probing are discussed. By using numerous conventional microbiological, chemical techniques, and molecular based methods, bioremediation can be studied in a comprehensive manner and the technology transferred to the commercial sector.     

Bioremediation of copper-contaminated soils by bacteria

Although copper (Cu) is an essential micronutrient for all living organisms, it can be toxic at low concentrations. Its beneficial effects are therefore only observed for a narrow range of concentrations. Anthropogenic activities such as fungicide spraying and mining have resulted in the Cu contamination of environmental compartments (soil, water and sediment) at levels sometimes exceeding the toxicity threshold. This review focuses on the bioremediation of copper-contaminated soils. The mechanisms by which microorganisms, and in particular bacteria, can mobilize or immobilize Cu in soils are described and the corresponding bioremediation strategies—of varying levels of maturity—are addressed: (i) bioleaching as a process for the ex situ recovery of Cu from Cu-bearing solids, (ii) bioimmobilization to limit the in situ leaching of Cu into groundwater and (iii) bioaugmentation-assisted phytoextraction as an innovative process for in situ enhancement of Cu removal from soil. For each application, the specific conditions required to achieve the desired effect and the practical methods for control of the microbial processes were specified.     

Review of MTBE Biodegradation and Bioremediation

Conclusive evidence of methyl tert-butyl ether (MTBE) biotransformation and complete mineralization under aerobic conditions in environmental samples and enrichment cultures is reviewed, in addition to increasing evidence of MTBE biotransformation under anaerobic conditions. The metabolic pathway of MTBE appears to have two key intermediates, tert-butyl alcohol (TBA) and 2-hydroxy isobutyric acid (HIBA). The first enzyme in MTBE biodegradation has been identified as either a cytochrome P450 or a nonhemic monooxygenase in different isolates. Mixed and pure cultures of microorganisms have utilized MTBE as a sole carbon and energy source. Cometabolism of MTBE with n-alkanes at rates of 3.9 to 52 nmol/min/mg protein has been documented. The presence of co-contaminants such as BTEX has either not affected or seemed to limit MTBE biodegradation. Some studies of MTBE natural attenuation have attributed mass loss to biodegradation, while others have attributed mass loss to dilution and dispersion. Recent advances in the assessment of MTBE biodegradation have indicated the potential for natural anaerobic transformation of MTBE. In situ bioremediation of MTBE has been enhanced by adding air or oxygen, or by adding microorganisms and air or oxygen. Bioreactors have attained significant removal of MTBE from MTBE-contaminated influent. Despite historical concerns about the biodegradability of MTBE, several biological methods can now be used for MTBE remediation.     

Bioremediation Potential of Terrestrial Fuel Spills

A bioremediation treatment that consisted of liming, fertilization, and tilling was evaluated on the laboratory scale for its effectiveness in cleaning up a sand, a loam, and a clay loam contaminated at 50 to 135 mg g of soil⁻¹ by gasoline, jet fuel, heating oil, diesel oil, or bunker C. Experimental variables included incubation temperatures of 17, 27, and 37°C; no treatment; bioremediation treatment; and poisoned evaporation controls. Hydrocarbon residues were determined by quantitative gas chromatography or, in the case of bunker C, by residual weight determination. Four-point depletion curves were obtained for the described experimental variables. In all cases, the disappearance of hydrocarbons was maximal at 27°C and in response to bioremediation treatment. Poisoned evaporation controls underestimated the true biodegradation contribution, but nevertheless, they showed that biodegradation makes only a modest contribution to gasoline disappearance from soil. Bunker C was found to be structurally recalcitrant, with close to 80% persisting after 1 year of incubation. The three medium distillates, jet fuel, heating oil, and diesel oil, increased in persistence in the listed order but responded well to bioremediation treatment under all test conditions. With bioremediation treatment, it should be possible to reduce hydrocarbons to insignificant levels in contaminated soils within one growing season.