蚯蚓中菲分布的分层次方法研究

The distribution of heavy metals in earthworms has been widely studied, highlighting the importance of the fate of these metals.However, little information is available on the distribution of hydrophobic organic contaminants(HOCs) within earthworms. The aim of this study was to propose a hierarchic method to study the distribution of phenanthrene(PHE), a typical HOC, in Eisenia fetida at several levels: sub-organism(pre-clitellum, clitellum and post-clitellum), tissue(body wall, gut and body fluid) and subcellular(intracellular and extracellular fractions). Earthworms were incubated in the soils amended with low(LC, 10 mg kg-1) and high concentrations(HC, 50 mg kg-1) of PHE and sampled at different time intervals. At the sub-organism level, the distribution of PHE was homogeneous among the sub-organism fractions in the LC treatment but heterogeneous in the HC treatment and gradually reached the following form of post-clitellum ≈ clitellum pre-clitellum. The uptake and elimination kinetics of PHE in the sub-organism were well described by a one-compartment model. At the tissue level, the concentration of PHE followed the order of gut body fluid body wall; while at the subcellular level, the concentration of PHE in the extracellular fraction was 1.23 to 4.68 times higher than that in the intracellular fraction. Therefore, the simple circulatory system of earthworms may account for the PHE distribution at the sub-organism level. Partition pathways(passive diffusion) of PHE between the body wall, body fluid and gut as well as the processes of PHE entrance into the inner cellular compartment via passive diffusion were experimentally supported.     

Effect of Waterborne Zinc on Survival, Growth, and Feed Intake of Indian Major Carp, Cirrhinus mrigala (Hamilton)

The effect of waterborne zinc on survival, growth, and feed intake of Indian major carp, Cirrhinus mrigala (Hamilton), advanced fry was studied under laboratory condition. Survival rates of C. mrigala advanced fry (2.71?±?0.49 g) after 30 days exposure to control (0.01), 0.03, 0.06, 0.10, and 0.15 mg/L zinc using the static renewal method in freshwater at pH 7.3?±?0.2, temperature 26?±?2°C, and total hardness 114?±?16 mg/L as CaCO₃ were 100%. Growth of the fish exposed to 0.10 and 0.15 mg/L of zinc was significantly lower (P?<?0.05) than in control (0.01), 0.03, and 0.06 mg/L of zinc after 30 days of exposure. However, there were no significant differences (P?>?0.05) in fish growth between 0.03 and 0.06 mg/L zinc concentrations. Feed intake rates were significantly (P?<?0.05) reduced in the fish exposed to 0.10 mg/L and higher levels of zinc. The zinc accumulation in the whole body of the fish increased with increasing concentrations of the metal.     

Bioremoval of Surfactant from Laundry Wastewater in Optimized Condition by Anoxic Reactors

Effects of ethanol and nitrate on linear alkyl benzene sulfonate (LAS) degradation were investigated using central composite design. At experimental design, removal of 99.9% was observed in batch reactors (1 L) with 9.8 to 41.2 mg L^?1 of LAS. The batch reactors were kept under agitation at 120 rpm and 30 °C. Ethanol (co-substrate) and nitrate (electron acceptor) were statistically significant factors (p?<?0.05) in surfactant removal. Optimal values were 97.5 and 88 mg L^?1 for ethanol and nitrate, respectively. LAS removal was kinetically investigated by varying surfactant concentration while using optimal values. Batch I (27 mg L^?1 LAS) exhibited greater degradation rate (K^LAS) (0.054 h^?1) in the presence of ethanol and nitrate. Nonetheless, in Batch II (60 mg L^?1 LAS), the K^LAS values decreased in those reactors probably due to inhibition by excess substrate for same concentrations of nitrate and ethanol added in reactors. As LAS concentration increased, the dominance of bacterial populations also increased, whereas diversity index decreased from 2.8 (inoculum) to 2.4 and 2.5 for reactors with both added nitrate and ethanol and those with only added ethanol, respectively. Probably, a selection of microbial populations occurred in relation to LAS concentration. The nitrate and ethanol, at able concentration, made it possible the induction of denitrifying microrganisms foward to LAS removal.     

Physiological Response of Daphnia magna to Linear Anionic Polyacrylamide: Ecological Implications for Receiving Waters

Linear anionic polyacrylamide (LA-PAM) is being considered as a soil amendment to reduce seepage and infiltration in unlined earthen canals. While polyacrylamides have been extensively used for potable water treatment, dewatering sewage sludge, coal and mine processing, paper manufacturing, and agriculture, little is known about its ecological impact to aquatic ecosystems. Acute toxicity (LC₅₀, 24 and 48 h) and chronic exposure tests (limited and continuous exposures) were conducted on Daphnia magna. In the chronic limited exposure experiments, Daphnia were exposed to LA-PAM for only 24 h whereas for the chronic continuous exposure the concentrations of 0, 0.5, 1, 5, 10, and 100 mg/L were tested and the endpoints of growth, onset to reproduction, fecundity, and mortality were measured for the duration of 32 days. There was no significant difference among the chronic, limitedly exposed organisms. The acute toxicity for LA-PAM was measured at 100, 150, 200, 250, and 300 mg/L. The acute test showed that the LC₅₀ for LA-PAM was at 152 mg/L. Overall in the chronic, continuous exposure test, D. magna was negatively impacted by LA-PAM at levels as low as 1 mg/L. Growth was reduced by 37% and 89% at 1 and 100 mg/L, respectively. Fecundity and onset to reproduction was impaired at 10 and 100 mg/L. Kinematic viscosity ranged from 0.98 cSt at 1 mg/L to 2.9 at 100 mg/L. At these levels, mechanical and physiological impairments due to the viscous properties of LA-PAM are the proposed mechanisms of reduction in the life history traits of D. magna.     

Desorption Characteristics of Three Mineral Oxides and a Non-crystalline Aluminosilicate for Supplying Phosphate in Soilless Root Media

The objective was to evaluate phosphate desorption characteristics of synthetic hematite, goethite, and allophane and commercial alumina after loading at maximum adsorbed phosphate levels to determine their potential to release phosphate at a constant, low level to sustain plant growth in soilless media and reduce phosphate leaching. Desorption isotherms were measured at pH 6.4 ± 0.1 using a continuously stirred-flow reactor. The time period during which dissolved phosphate was maintained within the range of 5–0.2 mg·L^?1 phosphate-P decreased in the order: allophane (12.4 d) > alumina (4.6 d) > goethite (3.6 d) > hematite (1.9 d). Allophane released the most phosphate during the desorption process (40% of maximum adsorbed phosphate; 12.7 mg?g^?1) followed by alumina and goethite (19–20%; ≈2.5 mg?g^?1) and lastly hematite (5%; 0.1 mg?g^?1). Allophane demonstrated the greatest potential as a phosphate-charged source for soilless root media, in amount and duration of phosphate release.     

Effects of Glyphosate on Somatic and Ovarian Growth in the Estuarine Crab <Emphasis Type="Italic">Neohelice granulata</Emphasis>, During the Pre-Reproductive Period

Adult females of the estuarine crab Neohelice granulata were exposed during the 3-month pre-reproductive period (winter) to the herbicide glyphosate, the most used pesticide in Argentina, at three different concentrations (0.02, 0.2, and 1 mg/L, as active ingredient). At the end of the in vivo assay, the body weight gain and the ovarian growth were estimated, the last one in terms of the gonadosomatic index (GSI), the relative proportion of the different kind of oocytes, and their relative size. A decrease in the body weight gain was observed by effect of pure glyphosate, at all concentrations assayed. Although no differences in either the GSI or vitellogenic protein content of the ovary were noted between any glyphosate concentration and control, a higher proportion of reabsorbed vitellogenic oocytes was observed in the ovaries of crabs exposed to glyphosate at 1 mg/L, together with an increased area of previtellogenic oocytes. These effects were confirmed in vitro, at a glyphosate concentration of 0.2 mg/L. In fact, a higher area of previtellogenic oocytes was seen when glyphosate was added to the culture medium containing ovarian tissue, but a significant higher incidence of reabsorbed vitellogenic oocytes was seen only when eyestalk tissue was also added to the vials, suggesting that the secretion of some neurohormone involved in reabsorption is enhanced. The obtained results indicate that glyphosate is able to harm, in the studied species, both somatic and the ovarian growth.     

Isolation and Characterization of the Tellurite-Reducing Photosynthetic Bacterium, <Emphasis Type="Italic">Rhodopseudomonas palustris</Emphasis> Strain TX618

A novel tellurite-resistant photosynthetic bacterium, Rhodopseudomonas palustris strain TX618, was isolated from wastewater and reduction of tellurite by this strain was investigated. The results showed that Rhodopseudomonas palustris strain TX618 could reduce tellurite to elemental tellurium, both anaerobically and aerobically. During anaerobic and illuminated growth, strain TX618 possessed a high-level resistance and removal efficiency to tellurite, that it could resist up to 180 mg/L Na₂TeO₃ in the medium and removed 91.9% of 90 mg/L Na₂TeO₃ over 8 days. The high efficiency in the removal of tellurite could sustain wide variations in pH (5.0–9.0), temperature (20–40 °C), light intensity (1500–3000 lx), and initial tellurium concentration (30–180 mg/L Na₂TeO₃). It could be observed by scanning electron micrograph (SEM), transmission electron micrograph (TEM), and X-ray diffraction (XRD) analysis that the cells suffered serious deformation due to the toxicity of tellurite, and the less toxic black precipaite (Te⁰) generated by bioreduction of tellurite mostly located in the central cytoplasm. This is the first study to observe that Rhodopseudomonas palustris can reduce tellurite to elemental tellurium, which will provide a new microbial species for bioremediation and biotransformation of toxic tellurite.     

Potential of Borago officinalis, Sinapis alba L. and Phacelia boratus for Phytoextraction of Cd and Pb from Soil

Heavy metal phytoextraction is a soil remediation technique, which makes use of plants in removing contamination from soil. The plants must thus be tolerant to heavy metals, adaptable to soil and climate characteristics, and able to take up large amounts of heavy metals. Most of the high biomass productive plants such as, maize, oat and sunflower are plants, which do not grow in cold climates or need intensive care. In this study three “weed” plants, Borago officinalis; Sinapis alba L. and Phacelia boratus were investigated for their ability to tolerate and accumulate high amounts of Cd and Pb. Pot experiments were performed with soil containing Cd and Pb at concentrations of up to 180 mg kg^?1 and 2,400 mg kg^?1 respectively. All three plants showed high levels of tolerance. Borago officinalis; and Sinapis alba L. accumulated 109 mg kg^?1 and 123 mg kg^?1 Cd, respectively at the highest Cd spiked soil concentration. Phacelia boratus reached a Cd concentration of 42 mg kg^?1 at a Cd soil concentration of 100 mg kg^?1. In the case of Pb, B. officinalis and S. alba L. displayed Pb concentrations of 25 mg kg^?1 and 29 mg kg^?1, respectively at the highest Pb spiked soil concentration. Although the Pb uptake in P. boratus reached up to 57 mg kg^?1 at a Pb spiked soil concentration of 1,200 mg kg^?1, it is not suitable for phytoextraction because of its too low biomass.     

Ectogenic Meromixis of Lake Hallst?ttersee, Austria Induced by Waste Water Intrusions from Salt Mining

Lake Hallstättersee is a holomictic alpine lake, which is influenced by salt mining since the middle Bronze Age. Beside the constant saline waste water load, two massive brine spills loaded the lake with additional 16,900 tons sodium chloride (??10,250 tons Cl^?) from 1977 to 1979 and 3,000 tons salt (??1,820 tons Cl^?) in 2005. The effect of waste water intrusions from salt mining on stratification of Lake Hallstättersee was analysed over a period of 40 years. Water density, dissolved oxygen and total phosphorus (TP) concentrations were measured and an exponential model was fitted to describe the wash-out of chloride from Lake Hallstättersee after the brine spills. Furthermore, the time required returning to holomixis and steady chloride content after the second brine spill was estimated. During the whole sampling period the minimum and maximum volume-weighted annual mean chloride concentrations were 23.58 mg/L in 1979 and 3.19 mg/L in 1998. However, the mixing regime of Lake Hallstättersee, as well as the chloride concentrations, varied considerably and exhibited three holomictic and three meromictic periods between 1970 and 2009. Holomictic periods were observed when the yearly density gradient was below 0.06 kg/m³, deepwater oxygen in spring above 4 mg/L and consequently declining TP concentration in the deepest water layer below 60 mg/m³, otherwise meromictic periods were observed. Our study showed that Hallstättersee was 13 years ectogenic meromictic and 27 years holomictic during the study period.     

Use of cyanobacterial polysaccharides to promote shrub performances in desert soils: a potential approach for the restoration of desertified areas

The importance of cyanobacterial polysaccharides of biological soil crusts in sand surface stabilization and soil nutrient retention has been long acknowledged. However, the role of cyanobacterial polysaccharides as a source of nutrition to vascular plants in crusted areas is ignored. In this study, the chemical composition of the polysaccharide synthesized by Phormidium tenue and the effects of its presence on seed germination and seedling metabolism of the shrub Caragana korshinskii were investigated. The crude polysaccharide synthesized by P. tenue was composed of 15 % protein and 58 % carbohydrate and showed the presence of 12 different types of monosaccharides. The addition of the polysaccharide significantly (P?<?0.05) increased seed germination and metabolic activity of the seedling of the shrub C. korshinskii. The optimal concentration for vigor index, root length, root vigor, and total N and P contents was 10 mg/L polysaccharide; for the germination rate, nitrate reductase activity, carbohydrate content, chlorophyll, and Mg²⁺ content, the optimal was 60 mg/L polysaccharide, while for K⁺ and Ca²⁺ contents, photosynthetic efficiency and superoxide dismutase activity was 120 mg/L. The presence of the polysaccharide increased seed germination rate, ion uptake, and photosynthetic activity by affecting the electron transport chain and decreased oxidative damage by eliminating reactive oxygen species in C. korshinskii, thus promoting shrub performance in crusted desert areas.     

Low Concentrations of Glyphosate-Based Herbicide Affects the Development of <Emphasis Type="Italic">Chironomus xanthus</Emphasis>

Glyphosate is an herbicide commonly used worldwide for weed control and generally applied as part of a formulated product, such as Roundup. Contamination of surface water by glyphosate-based herbicides can cause deleterious effects in organisms, mainly in aquatic systems near to intensive agricultural areas (e.g., transgenic soybean crops). Given the lack of toxicological information concerning effects of glyphosate-based herbicides on tropical aquatic ecosystems, we aimed to evaluate the lethal and sub-lethal effects of Roundup Original® on the dipteran Chironomus xanthus. The endpoints evaluated included survival, growth, and emergence. The results showed that the 48 h LC₅₀ for glyphosate to C. xanthus was 251.5 mg a.e./L. Larval growth of C. xanthus was reduced under glyphosate exposure (LOEC for body length = 12.06 mg/L; LOEC for head capsule width = 0.49 mg/L). No effects were observed in terms of cumulative percentage of imagoes emergence. However, low concentrations of glyphosate caused delayed emergence of females (at 1.53 mg/L) and induced fast emergence of males (at 0.49 mg/L), compared to control treatment. The deleterious effects of environmental relevant concentrations of glyphosate (0.7 mg/L) observed in terms of C. xanthus growth and development suggest that glyphosate-based herbicides can have negative consequences for aquatic non-target invertebrates such as Chironomus. Multigerational assays are needed to assess the long term effects of glyphosate on C. xanthus populations. Finally, our study adds ecotoxicological data on the effects of glyphosate-based herbicides on tropical freshwater invertebrates.     

Fate of Heavy Metals in an Urban Natural Wetland: The Nyabugogo Swamp (Rwanda)

The Nyabugogo natural wetland (Kigali City, Rwanda) receives all kinds of untreated wastewaters, including those from industrial areas. This study monitored heavy metal concentrations (Cd, Cr, Cu, Pb, and Zn) in all environmental compartments of the swamp: water and sediment, the dominant plant species Cyperus papyrus, and fish (Clarias sp. and Oreochromis sp.) and Oligochaetes. Cr, Cu, and Zn concentrations in the water were generally below the WHO (2008) drinking water standards, whereas Cd and Pb were consistently above these limits. Except Cd, all metal concentrations were below the threshold levels for irrigation. The highest metal accumulation occurred in the sediment with up to 4.2 mg/kg for Cd, 68 mg/kg for Cu, 58.3 mg/kg for Pb, and 188.0 mg/kg for Zn, followed by accumulation in the roots of C. papyrus with up to 4.2 mg/kg for Cd, 45.8 mg/kg for Cr, 29.7 mg/kg for Cu, and 56.1 mg/kg for Pb. Except Cu and Zn, other heavy metal (Cd, Cr, and Pb) concentrations were high in Clarias sp., Oreochromis sp., and Oligochaetes. Therefore, there is a human health concern for people using water and products from the swamp.     

Effect of cadmium on the chemical composition of xylem exudate from oilseed rape plants (Brassica napus L.)

Abstract

Phytoremediation is a good technique for removing cadmium (Cd) from farmland soils. To remove Cd from these soils effectively, it is necessary for Cd ions to be transported to the shoot organs for later harvest. However, the mechanism of Cd translocation to shoot organs via xylem vessels has not yet been elucidated. We selected oilseed rape plants (Brassica napus L.) and established a method to collect xylem exudates from these plants. After 3 days of Cd treatment (10 µmol L^?1 and 30 µmol L^?1) the Cd concentrations in the xylem exudates were approximately 6.5 µmol L^?1 and 16 µmol L^?1, respectively. The detection of Cd in the xylem exudate indicated that Cd was moving to shoot organs via xylem vessels. The effect of these Cd treatments on the amino acid, organic acid and protein composition of xylem exudates from oilseed rape plants was investigated. The level of amino acids and organic acids detected was enough to bind Cd transported via the xylem. Sodium dodecylsulfate-polyacrylamide gel electrophoresis analysis revealed that proteins with molecular weights of 36 kDa and 45 kDa clearly increased in the exudates with Cd treatment. The possibility that these compounds are binding Cd in the xylem exudates was discussed.     

How Much Does the Presence of a Competitor Modify the Within-Canopy Distribution of Ozone-Induced Senescence and Visible Injury?

Many natural vegetation species have been shown to be negatively affected by ozone. This study has investigated how the presence of competing species in a community affects two common responses to ozone: visible injury and senescence. Monocultures and mixtures of Trifolium repens and Lolium perenne were grown in large containers and were exposed in solardomes to either a rural episodic ozone profile (AOT40 of 12.86 ppm h) or control conditions (AOT40 of 0.02 ppm h) for 12 weeks. The proportion of ozone-injured or senesced leaves was different in the different regions of the canopy. The highest proportions of injured/senesced leaves were in the plant material growing at the edge of the canopy and the upper canopy, with a significantly lower proportion of injured leaves in the inner canopy. The presence of L. perenne increased the proportion of ozone-injured leaves in T. repens at the final harvest, whilst the presence of T. repens decreased the proportion of senesced leaves in L. perenne. In L. perenne, the proportion of injured leaves at the edge and inner canopy decreased significantly when grown in competition, whilst for T. repens the reverse effect occurred in the inner canopy only. Different mechanisms appeared to influence the interaction between response to ozone and competitors in these two species. In L. perenne the response to ozone may have been related to nitrogen supply, whereas in T. repens canopy structure was more important.     

Genetic variability in symbiotic nitrogen fixation between provenances ofAcacia nilotica (L.) Willd. ex Del.

Summary Differences in nitrogen fixing abilities of 18 provenances (16 from India, 2 from Israel) ofAcacia nilotica (L.) Willd. ex Del. were assessed in sterilized sand in chillum jars and unsterilized field soil in earthen pots, at Hisar (29°10′N lat., 75°46′E long., 215 m alt.), India. There were significant differences in growth and amount of nitrogen fixed and stored in plants (P < 0.01) between provenances. The values ranged from 10 to 34 mg N/plant in sterilized sand, and 11 to 44 mg N/plant in unsterilized soil. Maximum nodulation and nitrogen fixation occurred in Sirsa provenance followed by Pali, Coimbatore and Chandigarh provenances. Medinipur, Hisar (local provenance) and two exotics fixed significantly (P < 0.01) lower amounts of nitrogen. These differences attributed to genetic variability among provenances ofAcacia nilotica. There were strong and positive correlations between number and mass of nodules with total nitrogen fixed in the plants. The results are important from the point of view of exploiting the genetical variability inA. nilotica in amelioration of wastelands.     

Lead (II) Removal from Aqueous Solution by Spent Agaricus bisporus: Determination of Optimum Process Condition Using Taguchi Method

In this paper, Taguchi method was applied to determine the optimum condition for Pb (II) removal from aqueous solution by spent Agaricus bisporus. An orthogonal array experiment design (L₉(3⁴) which is of four control factors (pH, t (contact time), m (sorbent mass), and C ₀ (initial Pb (II) concentration)) having three levels was employed. Biosorption capacity (mg metal/g biosorbent) and percent removal (%) were investigated as the quality characteristics to be optimized. In order to determine the optimum levels of the control factors precisely, range analysis and analysis of variance were performed. The optimum condition for biosorption capacity was found to be pH?=?5.00, t?=?5.0 h, m?=?0.010 g, and C ₀?=?50 mg/L. And for percent removal, the optimum condition was found to be pH?=?4.00, t?=?4.0 h, m?=?0.100 g, and C ₀?=?50 mg/L. Under these optimum conditions, biosorption capacity and percent removal can reach 60.76 mg/g and 80.50%, respectively.     

The Effectiveness of Zn Leaching from EAFD Using Caustic Soda

Electric arc furnace dust (EAFD) is a toxic waste which is mainly rich in iron oxide, zinc, and lead. Hydrometallurgical extraction of zinc from Jordanian EAFD in alkaline medium was investigated; NaOH, NaHCO₃, and Na₂CO₃ were used as leaching agents. The pH values for the prepared solutions were 8.3, 8.2, and 12.55 for NaHCO₃, Na₂CO₃, and NaOH, respectively. The effect of NaOH concentration (1, 3, 5, 7, and 9 M), contact time (5 min to 3 h), temperature (20, 40, and 60), and solid-to-liquid ratio (SLR; 20, 40, 80, and 120 mg/ml) on the leachability of zinc from EAFD were tested. The initial EAFD and the resulting leach residues were characterized using X-ray diffraction (XRD) and X-ray fluorescence (XRF). EAFD contained 25.9% Zn, 18.0% Fe, and 3.2% Pb. A maximum zinc recovery of 92.9% was achieved using 6 M NaOH at 60 °C with solid loading of 20 g/L and 3 h leaching time. NaHCO₃ and Na₂CO₃ were not efficient leaching agents for Zn extraction since the recoveries were only 2.6 and 4.5%, respectively. Zn and Pb were depleted in the residues with an E-factor of 0.5–0.6 and 0.1–0.25, respectively. Iron was enriched in the residues; the E-factor was around 2. The EAFD contained mainly zincite, franklinite, and magnetite. After 3 h leaching, only traces of zincite exist in the residues, while sylvite and halite were completely dissolved.     

Growth and Physiological Responses of Triticum aestivum and Deschampsia caespitosa Exposed to Petroleum Coke

Methylibium petroleiphilum PM1, which is capable of degrading of methyl tert-butyl ether (MTBE), was immobilized in calcium alginate gel beads. Various applications were explored to increase the mechanical strength of these gel beads. The introduction of 0.3 mol/L calcium chloride into the crosslinking solution, 0.002 mol/L calcium chloride into the growth medium, and 0.2% polyethyleneimine (PEI) as chemical crosslinking agent increased the stability of the Ca-alginate gel beads under the operation conditions of the bioreactor. The degradation rates of MTBE by the immobilized cells in the bioreactor system operated in batch and continuous mode , respectively, were compared. A MTBE biodegradation rate of 5.79 mg/L·h was reached for over 400 h (50 batches), and the immobilized cells in the bioreactor removed >96% MTBE during 50 days of operation. Molecular analysis of the PM1 cells revealed that microbial growth occurred predominantly as microcolonies in the outer area of the beads during the first 20 days of operation. The results of this study show that a continuous-mode, fixed-bed bioreactor reactor coupled with PM1-immobilized cells is a promising technology for remediating MTBE-contaminated groundwater.     

Biodegradation of the Anionic Surfactant Linear Alkylbenzene Sulfonate (LAS) by Autochthonous Pseudomonas sp.

Anionic surfactants, the earliest and the most common surfactants in detergent and cosmetic product formulations contribute significantly to the pollution profile of the ecosystem. Linear alkylbenzene sulfonates (LAS), a major chemical constituent of detergents, forms an imperative group of anionic surfactants. Bioremediation of LAS by conventional processes such as activated sludge is ineffective due to the low kinetics of degradation by unsuitable organisms and foam production. Hence this study was focused on isolating and characterizing indigenous LAS-degrading bacteria from soil. Twenty different LAS-degrading bacteria were isolated from detergent-contaminated soil by enrichment culture technique and degradation efficiency was assessed by Methylene Blue Active Substances (MBAS) assay and by reverse-phase high-performance liquid chromatography (HPLC) analysis. The most efficient LAS-degrading isolates, L9 (81.33?±?0.7) and L12 (81.81?±?0.8), were selected and identified as Pseudomonas nitroreducens (MTCC 10463) and Pseudomonas aeruginosa (MTCC 10462). The 16S rDNA sequences of the isolates were deposited in NCBI GenBank under the accession numbers HQ 271083 (L9) and HQ 271084 (L12). The isolates were capable of degrading 0.05?g/l LAS at 25?°C and pH 7.0?C7.5. Presence of a solid support caused biofilm formation which in turn enhanced LAS degradation. The isolates tend to display diauxic growth with alternate carbon source such as dextrose. These isolates also have the capability to degrade other xenobiotics like hydrocarbons and pesticides. Since xenobiotic pollutants in nature occur as a mixture of compounds rather than single pollutants, the potential of these two indigenous LAS-degrading isolates to degrade multiple xenobiotics gains relevance.     

ACC deaminase-producing bacteria mediated drought and salt tolerance in Capsicum annuum

Influence of drought and salt stress on different morphological and physiological growth parameters in Capsicum annuum inoculated with our isolates was estimated during the present study. Bulkhorderia cepacia was reported to possess the maximal, whereas Citrobacter feurendii the least plant growth promoting efficacy under salt and drought stress. ACC Deaminase activity of purified B. cepacia, C. feurendii and Serratia marcescens was 12.8 ± 0.44, 12.3 ± 0.56 and 11.7 ± 0.53 μM αKB mg^?1 min^?1 respectively. Under drought stress, B. cepacia showed maximum tolerance as it produced 4.893 ± 0.06 mg/mg protein of exopolysaccharide followed by C. feurendii and S. marcescens that produced 4.23 ± 0.03 and 3.46 ± 0.05 mg/mg protein, respectively. Chlorophyll “a” concentration was recorded 5.7 gm L^?1 in B. cepacia inoculated plant (without stress) and was sustained till 2.9 gm L^?1 even under the highest tested drought period. Chlorophyll “a” concentration in the B. cepacia inoculated plant under the highest tested NaCl concentration was 3.2 gm L^?1. Thus, bacterial inoculation mitigates the effects of salinity by the proliferation of root system, increasing plant biomass proving to be potential bioinoculum for alleviating abiotic stress.