石油烃降解菌培养基组分和条件优化

从新疆油田油井旁土样富集、筛选得到一株高效石油烃降解菌HL-6,经初步鉴定为红球菌属（Rhodococcus sp.）．研究表明,使用乙醇作为碳源制备液体种子液是可行的,之后采用单因素试验设计先后对菌株生长的培养基组分及生长条件进行了优化．结果表明,菌株HL-6的最适生长条件为：碳源（柴油）浓度为0．5％、氮源选择（NH4）2SO4浓度为8g／L、磷源为KH2PO4：Na2HPO4摩尔比为3：1、酵母粉浓度为0．03g／L、培养时间为3d、培养温度为20℃、pH=7．6、装液量为30mL、接种量为1．5％、摇床转速为150rpm．验证实验和预期一致,优化后降解率达到89．80％,比最初的78．50％提高了14．4％．     

土壤硒污染的生物修复技术

硒是一种较特殊的微量元素，人和动物缺硒和硒中毒之间的范围很窄，土壤硒污染能对当地的人和动物产生重大伤害。采用传统的土壤污染治理方法，成本高，效果差，而近年来兴起的生物修复技术是治理土壤硒污染的既有效又经济的方法。     

Environmental bioremediation for organometallic compounds: Microbial growth and arsenic volatillization from soil and retorted shale

Nutrient effects on microbial growth and arsenic volatilization from retorted oil shale and soil were evaluated in a laboratory study. Dimethylarsinic acid (DMAA), methanearsonic acid (MAA) and sodium arsenate amendments were used with added nutrients, or with retort process water added to simulate possible co-disposal conditions. In experiments with soil and retorted shale, dimethylarsinic acid showing the highest cumulative arsenic releases, in comparison with added inorganic sodium arsenate (SA). Low but detectable amounts of innate arsenic present in retorted shale could be volatilized with added organic matter. In soil, arsenic volatilization showed a direct relationship to nutrient levels and microbial growth. With shale, in comparison, a threshold response to available nutrients was evident. Distinct increases in fungal community development occurred with nutrients available at a level of 2.5% w/v, which also allowed incresed arsenic volatization. Codisposal of retort process waters with shale allowed arsenic volatilization without the addition of other nutrients. The presence of retort process water limited arsenic volatilization from the added organometallic compounds DMAA and MAA, but not from SA or innate arsenic. These differences should be useful in the definition of permissive and non-permissive environmental conditions for arsenic volatilization in bioremediation programs.     

Randomly Methylated β-Cyclodextrins (RAMEB) Enhance the Aerobic Biodegradation of Polychlorinated Biphenyl in Aged-Contaminated Soils

The biological removal of polychlorinated biphenyls (PCBs) from contaminatedsoils is adversely affected by the poor bioavailability of these pollutants. Twodifferent aged-contaminated soils containing about 890 and 8500 mg/kg of PCBswere supplemented with biphenyl and treated in slurry- and solid-phase aerobic0.5 litre-microcosms in the presence of RAMEB at 0, 0.5, 1.0, 3.0% (w/w). RAMEB,which was non-toxic and slowly biodegraded by the soil microorganisms, significantlyenhanced the bioavailability (from 30 to 50%) and the biological degradation (from 15to 55%) and dechlorination of PCBs in both soils and treatment conditions. RAMEBeffects were dependent on the concentration at which it was applied, the soil featuresand the treatment conditions. RAMEB enhanced PCB biodegradation by increasingboth the PCB bioavailability and the availability of biodegrading bacteria in themicrocosms. RAMEB appears a promising bioavailability enhancing agent for thetreatment of PCB-contaminated soils, not only for its positive effects on the PCBsbiodegradation, but also for its biodegradability, non-toxicity and relatively low cost.     

Degradation of textile dyes mediated by plant peroxidases

The peroxidase enzyme from the plants Ipomea palmata (1.003 IU/g of leaf) and Saccharum spontaneum (3.6 IU/g of leaf) can be used as an alternative to the commercial source of horseradish and soybean peroxidase enzyme for the decolorization of textile dyes, mainly azo dyes. Eight textiles dyes currently used by the industry and seven other dyes were selected for decolorization studies at 25–200 mg/L levels using these plant enzymes. The enzymes were purified prior to use by ammonium sulfate precipitation, and ion exchange and gel permeation chromatographic techniques. Peroxidase of S. spontaneum leaf (specific activity of 0.23 IU/mg) could completely degrade Supranol Green and Procion Green HE-4BD (100%) dyes within 1 h, whereas Direct Blue, Procion Brilliant Blue H-7G and Chrysoidine were degraded >70% in 1 h. Peroxidase of Ipomea (I. palmata leaf; specific activity of 0.827 U/mg) degraded 50 mg/L of the dyes Methyl Orange (26%), Crystal Violet (36%), and Supranol Green (68%) in 2–4 h and Brilliant Green 54%), Direct Blue (15%), and Chrysoidine (44%) at the 25 mg/L level in 1 to 2 h of treatment. The Saccharum peroxidase was immobilized on a hydrophobic matrix. Four textile dyes, Procion Navy Blue HER, Procion Brilliant Blue H-7G, Procion Green HE-4BD, and Supranol Green, at an initial concentration of 50 mg/L were completely degraded within 8 h by the enzyme immobilized on the modified polyethylene matrix. The immobilized enzyme was used in a batch reactor for the degradation of Procion Green HE-4BD and the reusability was studied for 15 cycles, and the halflife was found to be 60 h.     

Effects of slight variations in nutrient loadings on pore plugging in soil columns

The high nutrient concentrations that would exist near the nutrient injection well during the application of cometabolicin situ bioremediation may lead to the development of significant quantities of biomass at this point in the subsurface. This biomass can decrease the porosity of the soil to such an extent that nutrient injection is no longer possible. In this work, experiments were conducted using a porous media biofilm reactor, operated under constant substrate loading conditions, such that the pressure drop across the reactor was allowed to increase to maintain a constant volumetric flow rate through the reactor. Results suggest that biomass production, and hence biofilm thickness, near the injection feed port is highly sensitive to substrate loading. In addition, these variations in biofilm thickness produce dramatic differences in the pressure drop that is attained across the reactor. Use of the Kozeny-Carman equation can be used to predict that once a critical depth has been exceeded, the pressure drop across the bed will increase exponentially within biofilm depth. This result means that pressure is not a reliable indicator of the onset of pore plugging.     

Bioabatement to remove inhibitors from biomass-derived sugar hydrolysates

Bioabatement is a potential method to remove inhibitory compounds from lignocellulose hydrolysates that could be incorporated into a scheme for fermentation of ethanol from cellulose. Coniochaeta ligniaria NRRL30616, an Ascomycete that metabolizes furfural and 5-hydroxymethylfurfural, is a unique strain that may be useful for detoxifying biomass sugars. NRRL30616 and 23 related fungal strains were screened for the ability to metabolize furans and grow in dilute-acid hydrolysate of corn stover. NRRL30616 was the best strain for removal of inhibitors from hydrolysate, and abatement of hydrolysate by inoculation with the strain allowed subsequent yeast fermentation of cellulose to ethanol. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.     

Interactions of aminomethylphosphonic acid and sarcosine with montmorillonite interlayer surfaces

The smectite clay, montmorillonite, can be found in many soils throughout the world. In addition to its importance in agriculture and soil remediation, montmorillonite has extensive applications in industry both in its natural form and as a component of composite materials. The adsorptive properties of montmorillonite have been explored in relation to its interactions with the common herbicide glyphosate. This herbicide, when exposed to microorganisms in the soil is degraded, forming two products: aminomethylphosphonic acid (AMPA) and sarcosine. The atomic‐level interactions of these compounds with the montmorillonite interlayer surfaces are studied here using molecular mechanics. The final outcomes of these calculations are analyzed in terms of the proximity of the montmorillonite surface to the moieties of the degradation products. The phosphonate moiety was found to be the most important source of interactions for AMPA, while for sarcosine there was an even distribution between the amino and carboxylic moieties, and Na⁺ ion mediated surface complexes. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

Inorganic materials and living organisms: surface modifications and fungal responses to various asbestos forms

In a previous study several strains of soil fungi were reported to remove iron in vitro from crocidolite asbestos, a process that was envisaged as a possible bioremediation route for asbestos-polluted soils. Here, we get some new insight into the chemical basis of the fiber/fungi interaction by comparing the action of the most active fungal strain Fusarium oxysporum on three kind of asbestos fibers--chrysotile, amosite, and crocidolite--and on a surface-modified crocidolite. None of the fibers examined significantly inhibited biomass production. Even the smallest fibrils were visibly removed from the supernatant following adhesion to fungal hyphae. F. oxysporum, through release of chelators, extracted iron from all fibers; the higher the amount of iron at the exposed surface, the larger the amount removed, that is, crocidolite > amosite > chrysotile. When considering the fraction of total iron extracted, however, the ranking was chrysotile > crocidolite > amosite > heated crocidolite, because of the different accessibility of the chelators to the metal ions in the crystal structure. Chrysotile was the easiest to deplete of its metal content. Iron removal fully blunted HO* radical release from crocidolite and chrysotile but only partially from amosite. The removal, in a long-term experiment, of more iron than is expected to be at the surface suggests a diffusion of ions from the bulk solid towards the surface depleted of iron by fungal activity. Thus, if the fibers could be treated with a continuous source of chelators, iron extraction would proceed up to a full inactivation of free radical release. The fungal metabolic response of F. oxysporum grown in the presence of chrysotile, amosite and crocidolite revealed that new extracellular proteins are induced--including manganese-superoxide dismutase, the typical antioxidant defense--and others are repressed, upon direct contact with the fibers. The protein profile induced by heated crocidolite was different, a result suggesting a key role for the state of the fiber/hyphae interface in protein induction.     

Biosorption of heavy metals by bacteria isolated from activated sludge

Twelve aerobic bacteria from activated sludge were isolated and identified. These included both Gram-positive (e.g., Bacillus) and Gram-negative (e.g., Pseudomonas) bacteria. The biosorption capacity of these strains for three different heavy metals (copper, nickel, and lead) was determined at pH 5.0 and initial metal concentration of 100 mg/L. Among these 12 isolates, Pseudomonas pseudoalcaligenes was selected for further investigation owing to its high metal biosorption capacity. The lead and copper biosorption of this strain followed the Langmuir isotherm model quite well with maximum biosorption capacity (q _max) reaching 271.7mg of Pb²⁺/g of dry cell and 46.8 mg of Cu²⁺/g of dry cell at pH 5.0. Study of the effect of pH on lead and copper removal indicated that the metal biosorption increased with increasing pH from 2.0 to 7.0. A mutual inhibitory effect was observed in the lead-copper system because the presence of either ion affected the sorption capacity of the other. Unequal inhibitions were observed in all the nickel binary systems. The increasing order of affinity of the three metals toward P. pseudoalcaligenes was Ni<Cu<Pb. The metal biosorptive potential of these isolates, especially P. pseudoalcaligenes, may have possible applications in the removal and recovery of metals from industrial effluents.